Rust Programming Language Rust Malaysia, 10 Mar 2021

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From YouTube: RustLang Meetup Malaysia - March 2021

Description

Ivan Tham talked about diesel and experience with it with some examples of how the strongly type ORM looks like. On some additional time, he talked about a side project using rust to do parsing with nom and using inline_python to run some pandas code directly.

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Hey hello, welcome to rust, meetup match 2021.

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Today we will have ivan presenting on diesel. So without further ado, let's start the presentation. So if you are uh by the way, uh if you are interested in the meetup, you can go to uh you, can you can come join our call on google meet the this? Is the meet google me code, nz e and rje dvd uh without further ado evan? Are you ready.

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Okay, let's, let's start already I'll, be represented for today, so since news since last time we have our meetup one year ago, which is uh before the quarter. Nineteen, like january night called echo.

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Okay: okay, since last time we have our last meet up. During last january, we have uh 1.40 plus, and now we have 1.49 release. So it's like a year more than a year already. We have quite a lot we have like. uh We have a lot of improvement in a const area like there's a cons, function and stuff, a lot of them.

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Okay and and then today, I'll talk about diesel learn about diesel. Is that last time, when I was working right, I was uh when I was working. I was reading doing like goa m, which is a gold length library for om. I was working in this. I noticed that there's a lot of food guns where you can easily fall into so russ have uh russet a library called diesel which is popular. It's an om, although some someone doesn't doesn't call it om right.

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uh We can consider it itself, uh it markets itself as an om and query builder yeah, but the something someone might argue that it's more it's a more uh more towards queer builder. They could consider it so uh I tried golem such that it has issues with joints and if you do something out of normal because it uses a lot of reflection, magic and it uses a lot of reflection magic for gram, so it have a lot of uh sometimes in some parts it doesn't work, even though it compiles, but design is different.

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Lisa is a type safe, extensible, om and today I'll share my experience on using diesel and how? How much typesafe is that? So we first when we come into diesel right, we need to know that it is not you, you can't, you can't think of it as the other om that you might have seen, because later I'll explain that so reset is fast. It's built for performance, okay, before performance as in they have a benchmark as because there is a alternative to diesel, includes sql.

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In in rust as well, so this one is, uh this is type safe. So that's why they can say preventing runtime errors, but it's type safe to a certain level. So I have experienced some food guns in for it such that it doesn't have like uh in some parts, very specific parts, and it gets runtime error instead of compile time error.

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But there's like some limitation in perhaps some limitation in the type type system such that it didn't implement those parts it can be done, but uh it wasn't there because it's something new for that part, so they haven't fully explored that yet so sqr x is an alternative to diesel, whereas sql x takes a takes a different approach where you write pure sql and then the sql and then the sql will be checked during compile time when you compile the sql, when you compile the stuff with sql x right, you can use their macro called query and they also have a function, but you can use the macro and the macro will connect to the database, and then you check whether that query is correct or not.

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So it does it in another way, but this doesn't do it that way. Listen put all of those sql information into the types itself, so that the provides like built in the build dsl for uh doing dealing with types.

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So that's how they do it. So you need to know. Sql access is an automate, but it's very different and some some others may not prefer the both of these. They may want to write like tokyo postgres, which use the lower level directly but yeah diesel.

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So uh when, when you get started, you look, we will see some examples here.

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This is like roughly what diesel looks like, so these are the generator code and, and then they they won't have a relationship, and these are like roughly how diesel looks like and they also users derive to derive like the stuff to be queried and for inserting data. Usually they have in this right. They have a pattern where you, you create a struct for like different items that you are doing, for example, because uh usually you see people like if you have a struct for user people, have a strap for a new user user.

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Is for creating user is for creating a new listing users where the users have id, and if you notice the, if you use user right, it will be draft queryable and then, if you use like a new user, it will be derived in suitable. The difference is that new user usually don't include the id. You only include what you want to insert and other values being like auto generated or default values.

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So you may need some extra boilerplates where for different queries with a different amount of fuels, you you may need to use a different struct for that. This also helps to prevent some.

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Like some issues like let's say uh it doesn't do like default values or special case in some stuff. So all the fields have to be there and must be used and later I'll talk about this. How they work? It's, not you, don't you don't think of them as models, you think of them as like queries to be called stuff to be correct, because it it doesn't work like a model in other languages.

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It can't be considered model it. Can. It can be considered something like a query.

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So for updating data is a bit similar, so this how roughly how it looks like then we can get started to do so. So this.

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Oops looks like ivan is having some connection problem wait come.

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Back one, let me check.

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I haven't, are you.

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Let me check if oven is still.

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Iron is not responding to.

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To my telegram messages or him to see what's happening over his, I side hit my foot gun right.

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Let me give him a.

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Call oh he's having some connection problem. Oh, he should be back in a minute.

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Meanwhile, if you are interested in joining the.

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The meeting you can come by visiting this link.

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Dash meet.google.com.

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Let's see if iron is coming back or.

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I ivan is gone.

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However, needs to reboot his.

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Everyone is asking where ivan is.

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Iowan is restarting his network, so he should be back in about a minute or two.

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So meanwhile, if I'm interested in participating in the call you can join us by visiting this link, we might need to get ivan to start over.

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The slides are not updated properly on youtube.

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An iron is taking forever to restart his network.

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I'm very sorry about.

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All right, I haven't just restarted.

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All right can you I.

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No, oh, can you generally start the the top, because uh youtube was having problem refreshing, the the slides.

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Refreshing refreshing website.

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Your slide were not shown in the video.

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Gone again, why why are you doing this? For me, evan.

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I won't please come.

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Do I have sound.

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Okay, okay start work.

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uh Okay start from what everything yeah from diesel.

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Second slide, I think after the 1.499 rush.

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ah There's no slice, I didn't show anything. uh I I.

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Yeah there's no side. The last slide is about the grass 1.40.

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Now can see you can see ready screen.

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Okay, so oh I talked a lot, but never let me start again so diesel I thought uh just early. I say talk about this. This already.

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Yeah but to be safe, I guess you, you should start.

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To talk about itself, okay, so it's a type safe form, although some people don't consider essence.

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In rust is a popular one, most popular one. The alternative includes sqlc the excel sqlx, which does thing which does things quite differently compared to diesel. Well, it does is it allows you to scale.

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Sqlx have bought async support, diesel doesn't have, and I can explain a reason next time, and uh so it supports uh sqlx supports like a few more a few more drivers other than no. These are only support, postgres, mysql and sqlite, but sqlx support a few more drivers, some more srx support like uh the pura drywall.

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Unlike diesel, this doesn't support the purest driver.

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Yet no one wants to do that, but the reason the reason why diesel didn't support the purest driver is that, because the poorest drivers, for like the bicycle cannot be compared to the c driver, is that a lot slower compared to the c binding? So this is to use the c by index the original c bindings and why? Why uh do we want to use these like one of the things, because it's type save it prevent runtime error?

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This is safe to us for a certain level where, like sometimes new features, are faced uh certain scenario where there is error on runtime instead of compile time, but most of the stuff is like when usually when it comes, it will work in diesel, but sometimes the compiler compile error, for this is quite hard to understand because, like because diesel uses a lot of different type type magic, you can call it so and then it's also a bit of a performance.

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It's quite fast and of course I think raw sql should be faster, but diesel it should is quite fast and productive. uh I don't know how. How good is that? So they still have like a built-in dsl, where you can have multiple dsl, where you can use the domain specified language to do. The querying you can see like these are all like piezo code and it will generate the it's like a builder or sort, but it's the corresponding types of rust.

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Sorry, sorry I haven't, can you enlarge the screen for a bit because it's too small to see on the screen.

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uh It says, like uh you, can do something like this and then it will do like this, so these are generated by diesel. You don't. This is like diesel schema it's generated and they generate dsl for you and then well it does it generates this. So these are diesel code. It's a more complex one, of course, later I'll show even more complex, even more complex one which doesn't even work.

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I mean I'm stuck, so I need to do raw sql for that, but this already supports quite a lot of different stuff. Like uh this utilizes the derive for code gen, there's a queryable, the ef variable is to query you'll notice that there's a there's a queryable and there's an insertable in these. So these are different. You can't think of them as models.

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It doesn't work the way similar to other database where we have something called model digital. These are, you can think of it as what is being correct in the sql. So this side, the select id version id downloads counter that actually is not by name it's a this one. You can't think of it at this because this one works using the order.

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So uh it's a it's a bit different, such that the queryable. It looks at the id the i32 i32 this, but it doesn't look like this. Why? Because what if you want to use like uh sql like aggregation like count or you want to do something like uh average?

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So that's why they don't look like this and then this without diesel and for inserting we have insertable. Usually we don't do the same. We don't use the same.

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Okay, we don't we don't use the same struct as uh I wouldn't say: let's boil plate, because it's quite it's quite still, some by the way, because for different queries, you need to do different struct and this one. This time you have to like uh you'll, see that if you have user struct, usually you have you also have a new user strap new user struct? Usually you will have like derived insertable and user derived queryable, because why?

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Because when inserting you don't know the id, so you don't put id in and this you need to fill in all the all the fuels here. So it's not optional. So for all the fish you need to put in something.

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So that's why uh this also, although it's a bit more boilerplate, but you you can make sure things don't go wrong like you, don't insert id right! So that's why id is not there when it's inserting and when querying id. Is there because you want to get the id.

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So that's why you can think of it as like like this, so you can think of, like name as the first one and the hair color as the second one, except this I I think insertable also is ordered by uh order by the type and there's also queryable by name derive. If you want to look into the if you want to use raw sql, and these are like batches and- and this is quite economic in some cases because it it can like you- can use different types.

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For example, if you want to use, if you want to use load right, you can. The decent documentation is quite good. I mean on the normal ones, it's quite good, because it includes a lot of stuff, but the guy is not. The guy is not very comprehensive, but the normal documentation is still still quite good when they have a lot of things recommended and a lot of stuff have the examples you can use the same load function to return.

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uh You have written a single field, so you can. You want to return like a tuple also can, and you want to return the struct okay and that's why this struct works like looks sort of like a tuple.

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This is how you think of the queryable. You can't think of it as a model and when you get started with diesel, am I too fast or do I do you all have any questions up to now about the diesel.

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uh So far is so fun, so sofiane asked whether this is similar to tto.

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Well, I I guess we should just move on. Then we shall collect all the questions at the end.

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We can answer all in one shot when you get started right. Lisa uses like a feature feature gate say if you want to use. Postgres you'll just specify the postgres in this feature, and you want to support. If you want to use sqlite, you just use sqlite here and mysql as well. You put my sql here, so this is usually how you use diesel.

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It also comes with a cli, the ci. You can do migration and you can do mainly. I use it for migration and you can do code generation.

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Oh too, big yeah, you can do migration and code generation. Basically, that's what it does. Can you print schema like this?

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Okay, this is the so this is what the desert code generation, so it what it does is in these two right. You, you write the you first, how it works in decision is like you. When you want to do migration, you will need to write raw sql to do migration, so in sql first, you will do the thesis setup.

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Then you you create a migration and in the migration you need to write raw sql. You need to write something like this.

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So, unlike other language, uh disa doesn't provide like auto migrate as in like because they don't have the concept, the it they say like models, and it will automatically create the database models for you. So what you need to do is you need to create the structures yourself like you need to run. Write the raw raw queries yourself to make sure the types is correct and others is correct after you write this, so uh you just run the you can run the migration.

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This will run the migration and then like.

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ah It's already run your real redo yeah. So this will run the migration and then you can do like and then what you can do is generate. Let's.

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Okay, never mind don't follow this.

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Of course you can. If you are interested, you can read the guide, getting started guide. It's quite simple and.

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So what it does is, usually you print a schema, and then you have you can see in my schema. It's generated this isn't the normal practice in russ, where you generate ras code. Usually you just write macro yourself, but this does it this way where they generate this? These are the table is like a diesel dsl. You don't usually write this yourself, so why does it these are all generated by diesel they're running by this as well? Oh, no yeah! It's generated by diesel.

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Just a request: can you have it? Can you enlarge the text size a bit because it's.

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Hard to read from the.

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Just a fair bit.

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Time, okay, so uh why so, maybe you can look into what is the generator structures in diesel? Is the local documentation.

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Hello: okay: this is.

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Okay, so these are the generator structures that I have no schema, so it it will generate some dsl like this, so you can use it like uh you, okay, you can use it like like this, like the one show, so I have written like uh a few series of this. I have some experiments, so maybe I'll share a bit on the experimentation.

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So uh when I get into diesel the hard thing is like the learning learning the different you need to. The few things you need to know at first is like you need to understand.

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Okay, so I have a just now the example that I showed you have a structure like this and then I want to do a join. So I I have to do some drawing like this, so these will have like by default you you can don't do select and then you can. uh You can have that explicit, select or empty select, and you can do something like this and then it will generate some queries like this.

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Hey so long, okay, so uh what what I want to do here is I want to like create the table. I want to find based on the users that have name john, then I want to select the related commands or post and the users I'm going to select the comments body, what what this user commented and what on what post this user commented and on the username, because yeah, it's john, so all you can see here is this- is the generator dsl yeah user's name as in like here, hello, schema.

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So these are the generated one and then at first you might be confused here, because here, if you, if you import star here, hello, schema uses dsl star. If you import here, then you'll be a bit confusing such that because you have, this is re-exported as users, so your user table is now called like, for example, users table is now called.

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Users is a bit confusing at first such that. If you have multiple tables, then you wouldn't want to do this, because the examples in digital documentation shows both way is to use like import. Hello, schema users and then use users table.

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Ivan I can't hear you from.

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ah Someone is gone again.

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I guess ivan is still having his never problem.

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We shall wait for him to come back. Meanwhile, if you are interested in joining the call link is here.

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Let's wait for about two minutes for him to come back. I probably should start a countdown timer, some somewhere.

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I mean you should start paying your your bandwidth bills and your your.

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Evan, where are.

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Hello, hello, okay, maybe I I I don't turn on video. I just skip lazy to get my phone back for review.

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And I'm okay already right. I have sound.

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I think just now I talk until the I believe here, so this is a dsl to do inner join, so they have dsl for a lot of things like uh you can do inner join and you can even do count recently. I do count and, and then there's also a function to do count, so you can do like select count dot first, so that has support for something like this.

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Hello, okay and you can even do like.

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So this is like update from this. Is that I'm trying to do like an update from experimentation and then next I wanted to try like a.

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Multiple drawing experiment, no wrong and and then and then I want to do like um update from so I want to update from, like, let's say, update post set something wear something. This is a simple in diesel. They considered.

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They considered this as a simple version.

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Okay and and then see your sound.

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Yes, why are you showing.

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The youtube, so they consider this as a simple example, you can see the binds here like in this one is just now the debug query that you will see. So what you do here is in the user table. You select the user id and then you do a filter and then uh you you can filter it correctly like using, and then this is doing like a sub query already this yeah equal to any sub query.

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So what it does is uh this part right is like a post user id equal to any it's post user id and then equal to any is within this part. This is a sub query, so this can also do sub query and then, and then it works, and here yeah here. I noticed that what I learned is the dsl part is a bit confusing at first, but after you get to know the docs like you get to know.

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Oh there's a you need to differentiate between users dsl and like the hello schema users and hello, schema users dsl that part. So at first you might be a bit confused on that, but uh there's not an issue there.

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So the error will be a bit confusing there at first, but once you get to know it, you know that you use this when you are dealing with multiple tables, and you use this when you use a halo schema use this when you're dealing with like a single single table.

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And then also the other experiments like join drawing not exist wrong.

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Am I wrong so what I want to do here is, uh I want to do like undefined in one table, and I I want to find that so there's two tables I want to find in one table that doesn't exist, find stuff from two tables and how to reword this.

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Okay, so I have like post and I have comments, so I want to find all the comments that doesn't have any post.

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Oh, oh, the post that doesn't have any comments, so it does select from the post and then we will find that all those that doesn't have uh you'll find all those that doesn't have any id. So you see that it generates the generated, correspond. Okay, the post table. You can do a left join here. These are two left joint correctly, but diesel doesn't support the composite join composite joint is like, if you don't know, composite composite joint is like something like this.

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And then uh comments, this is like uh composite join, but this doesn't support this. Yet they also say it's for performance reason, so these are only support, left, join and inner join like left, join inner join, but there's no right join.

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I think. Maybe it's not required, so they didn't support right, join.

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And then yeah, so basically you do something like this post tables, so uh you can do like the tape you can. This is the original dslr way. I use the.

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It's like use, schema post and then you just use this post table and you can do post title. You can do post id and then like within the dsl right, because it implements some trade so in detail. You need to learn how to write the trades like comments.

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This is comments right and then it will have all the columns because you can see that it re-exports all the columns right. So you can use this all these columns directly id. So you need to write. The sum of the trades is useful here like, for example, you can see that there's quite a lot of trade being implemented.

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For example, I.

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Yeah, you can see expression.

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So you'll see based on documentation, just search for something like this, and then this is for the field, and then you can search for is now, and these have like all the like equal, rather than doing like uh string, rather than doing string, equal you'll see like uh equal using the function methods on expression methods, so you can call it like name, equal and e. Something like this also support like excluded, like even with I tried doing upstairs. It also support absurd and there's a one that excluded thing here.

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So this is like how we want to do something like this and then this is something harder already I tried doing offset so what this one do? What in this, what I want to do is like uh so up till this point when I get into upset, so I learn like diesel. Oh, it's a lot easier, a lot easier compared to the past, where I had to figure out a lot of stuff.

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So right now this time it is a lot easier to do stuff already, when, especially when it follows the default values, so for inserting right so for inserting, usually you do.

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So, actually you do this for inserting insert into, but for select right. You don't do like select from no you don't you don't usually don't do this. There are some functions that you don't use it in diesel, such that some in some cases you may need to use it.

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So this like insert into you, can you can see like you can insert into the table, but I I don't want to just insert into oh so, okay. So here's also one thing where I like is in values right. You can see these values you can use to post.

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You can use like name equals to this, which means that you can. You are only inserting name. So if users tables only contain name, you can do like this name equal tools.

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This is the original developer of diesel, one of the main developer there or you can also use tuples where you can do like a new user id equals to one. Of course, this is not like the normal equal. You see. This is not the in the. Where course, not the not not the id equals to in a way, but this is the id means. One and name is john and then values, and you can also use a you- can even use a vector.

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You know if you want to insert like batch users right and I can insert it the same way and you just use the same thing and that's quite interesting. I believe, and then you can also insert with structures, but the structures need to derive insertable and you need to have code table name but like. If you miss something like this, then error will be quite confusing at first, because the error doesn't sometimes doesn't point to the correct place. But if you miss this and yeah, this is how roughly, how it's done.

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Okay- and one thing to note, is uh diesel, because this and code stuff in the type right it even has like different scripts for different back ends. For example, returning they even have a trade call support returning cost, which means that the back end supports returning like, for example, uh sqlite, doesn't supports returning right.

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Returning is something like when you query right. You can get back the like when you insert you can get back. The original data like uh like you can give it original id what you have in what you inserted and you can get back the original fields that you insert.

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For example, when you do execute when you want to insert your, I think you do execute right.

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Now, in examples yeah, you do.

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Execute yeah so it'll execute.

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And I think some of these have.

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Yeah, like some some of this part right because sql sqlite doesn't have doesn't support returning, so you can't do a return like you can't. You can't get the inserted row in this case for sqlite. That's why I remember that's. Why that's why there's no implementers for this.

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That's why there's no implementers, but uh for like something like something like the postgres supports this so like in different. If you use different backends right, some of the features might not be there. So some of the parts you can't use the same. You can use the same rasco for everything, because they even support like diff even for different features. They even implement it in using types.

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So there's something quite mind-blowing to me when I first saw they even have other supports, like a support default keyword. Example on complete yeah. This support on conflict, so right now uh on config is only implemented for mysql, no postgres and sqlite.

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Although my sql have it last time, but they haven't implemented it yet so it means that they don't have this for mysql until someone implements it. So this is upset, so you can do on conflict and they can do update, but I find that there is a food gun here. uh What chilean want to hear is it? Is it still there?

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Okay, so because uh absurd is new, so on conflict? What you can do is you can put anything here uh you you might you can put that, even because the id is absurd right on conflict supposed to be something that is either a primary key or it's a unique value, but because right now they don't have meta data information on the type, whether that type is a primary key or a unique value.

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So basically they accept all the columns here, and I I tried putting name here and then you you'll get a runtime error for this. Like.

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This project is this:.

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For these experimentations right.

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For for this experimentation, I have like two binaries uh created, because I have a bin that call another variable called iit to initialize the data, so I want to attach insertion. So this is like how I insert the data into that.

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So there's a I just create like vectors and then just insert, execute, wrap and insert and then just insert another and then just insert again.

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So this is how I test it, and then I have another main to try out the queries that I want to do. Experimentation on. Of course, I just keep printing out the queries every time I run it.

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Excuse me so no such tables.

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So I didn't run my vision, I run the iip and I run the hello, so you can see I am inserting this into uh so this is upset. So if, if the id is already there right, because I'm.

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Because I'm inserting the id2 right because I id2 is already there, so it will change the value to john.

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So I'm selecting.

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So roughly like this, and if I change this to.

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Like I said name it, it will run, but then you get a runtime error instead of compile time error like I mentioned before, but uh I think it only happens for this part because I didn't get to see.

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Okay, you, you can see it's a full gun, but I don't think this guy is so serious. Okay, right now, mine, so you'll see that you get runtime error rather than a compound time error.

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So you get inserts because, uh but I think adding support for this to move this runtime error to a compiler time. Error is not that hard. I don't know I didn't try. Maybe I'll try doing it, because this auto is not doing that.

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So this is the program that I mentioned and then okay, then we have another okay, last project that I work on.

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Okay, so this last project I start facing some issues. I. What I wanted to do I want to do group by okay group. Buy is new in diesel, so I need to use nightly for that or same as the last project. I also need to use lightning for that nightly diesel, because the last release is 1.4 release which doesn't have a group buy and other stuff, so they are still open for feedback right now.

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So I'm trying to do is I wanted to do a group buy and count. So I want to find that, based on this user, for based on the user for this, for grouped by the user and post, how many based on okay, let me let me think, okay, based on this tree right.

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So, based on comments, no group, so I'm grouping by this group by post id and user id so for each post and user. How many? uh How many comments are there for that post, end user based on the post, end user, so like, for example, in one post, a user may have commented multiple times, so I want to count in total. How much? How many is that so at first I I want to try something like uh I even tried something like this, which is not already as not a balance equal, but this doesn't compound.

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So that's expected! Then I do. I want to do something like.

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So I want to try this indeed in diesel, but it didn't work.

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So it's something like uh this.

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So I have to do something like this in comments table. I want to group by this and select and it didn't work and.

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It didn't compile, they say it because they say desert doesn't support like this. So you see like a bunch of type errors. There's a lot.

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Because this is not supported.

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Why? Because I want to, I get the account in the sub query already, but because this doesn't yet support elias thing, so I mean a license as in count like like this id as I count, because this doesn't support this. Yet there's an active pr on that. But nobody continue. The original author wrote way in progress, go in progress pr, but he didn't finish.

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So I want to do the same. I don't know how to reference. I don't know how to use this to reference this, so basically this is like and what something that did the level of support. It's quite it's quite interesting already, because there's a lot that, based on this aggregation right, listen even take into account like what you grow by and what you select say if you grouped by something, but you didn't select that this will give an error.

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So that's already quite impressive. I believe like if you go by this, but you didn't select this.

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They will get error.

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I mean you get arrow here, because the types is incorrect, like the type here is incorrect.

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But never mind I'll continue, but this is something like up to the limits of roughly what diesel dsl currently supports. Worst case, I went and try out raw sequel, so I need to write.

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So I need to write my own struct like a comment count, so this query query by name what I need to do is I need to specify the types myself and it's not right and oh y'all know it's kakun. Can you mind if and if this is like uh and if the type is correct? It's wrong right, you'll. I also get an error like this and it's very weird right.

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I see this error, but I don't understand why I get this error, but I asked in a guitar channel- and they mentioned that, oh because big int is not for this, so I need to use thumb I-64, but yeah this. This part right. If I didn't the first part, if I didn't do the second query, it works, but you can only get the user id and post id, but because I don't want to do another query again. I want to do like a sub query thing, so I can't do that. So what does I need?

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I need to write raw sql and then I write the this and then this will be up to you whether you write this correct or not.

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Whether right is correct, you can do a bind you need to if you want to bind stuff in, you need to do like a bind here by using the type inside here like.

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Yeah something like this so this this is another layer of diesel where you you don't want like right, full raw sequel, but you want to write like some way halfway in between. So you can do something like this.

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So is that you, you have the choice to write, use the full quality, the full dsl, that these are provides that just I showed a lot or you can use this halfway, half bit dsl or you can use the ros raw query, but sometimes I find valkyrie very good in good enough for cases like this I'll, maybe fall back to queries, and this also provides like say: if you want to use some special functions in postgres right, you can still use it. I don't know what is that called, but I think you can.

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You can even provide a macro to generate sql function say the function is not in d, so it's not supported in descent, but you can just write like this and then it can generate the thing it can generate the function for you in let's say: postgres have a certain special function, so you can use those functions.

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Yeah, so roughly this there, you provide the level two to something like this, so a lot of things are covered, so I discussed a lot of things like towers is like they have a lot of dsl supported.

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You can see that they there's even relationship association and but there's also a bunch of uh across here and yeah. This is like what I learned from diesel is like they can. They do put stuff in type like if you want to look at their group by you'll, see that they even have like a very grouping where a lot of these are encoding type and aggregate, and then this oh look, so these are all done by diesel to make it tight safe.

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So they put in a lot of effort for this and the documentation as well yeah. So these are very interesting and I find it quite good. I feel up to you now, it's quite good from what I see. Let's see that they really make it type safe to prevent any food guns.

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Okay, I thought about this: is there any questions?

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Okay, I can talk about later. I can talk about bonus type bonus, section.

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And any questions.

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Any questions to be asked to our speaker.

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Okay, I can unback my video now.

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I need to open my phone first questions, questions.

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Yeah, so this is so how what do I think? How is it see.

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No question maybe I'll share about a.

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Bit of experiment, I've done.

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Lately, what I was trying to do, okay, this is what stock stock, so what there is like a stock there's like a stock uh data and then I want to get the price, and this is what I I did so I what what it involves is, I have like uh it will download the data. So this users request blocking request.

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Usually I'll just uh to our trouble, I will just use the blocking api of request and I happen to need gzip. So I also need to rgc because if I did add this I'll see scramble data and I use norm for passing, because I was doing it with my father. My father was doing it on pandas and then I say I don't want to use pandas. I want to write in grass, so I was using a rust already and I finished it first and then you have one.

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So I was writing writing a custom parser using norm and maybe I'll share a bit on what I don't like about now. So you see this right in norm. You see a bunch of this.

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Like you see a bunch of this bunch, I don't like this. uh Why we need this? Is I just added a lifetime in here yeah, I just added. Originally I put this as string.

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And then I just added this and I need, to all add all this lifetime. You know how many of these all these, if without the lifetime, you can just write it like this.

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You can write it like this yeah, a lot easier right.

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A lot can you write like this without the lifetime a lot easier, but then uh because if this is like str right, because this is like a static sdr and then when I change it to string which which became like uh sdr and then it suddenly became so unergonomic, where everything I need to add all this bunch of stuff and then I also need to add all to other functions, but otherwise it will be very nice to use, I will say norm because, uh but I've spent some time troubleshooting attack yeah, I don't even know which tech you have errors.

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The errors is a bit hard to understand.

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So what this does? I don't even know what it does now, so it uses pr3. So I do the passing and in.

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So norm you need to know like you, you can write, you can write past right. No, no! It's a password combinator for us where you can write some functions, merge the functions together and then do the passing, but I just find this only this part now I'm going to make. But other part is quite quite nice too right where I just write one part and then I just copy paste copy paste everything else just copy paste, although I can write a function for you, I detent lazy, so lazy to write functions for that.

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So I just paste everything and all the passing similar or just pass, plus, plus plus yeah, and then I pass all the data and then I even do a python. I tried writing some python here, which I uses inline python. For that.

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Yeah, so you see that you can inline python. Maybe I should run.

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It not to excel or.

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So these are like uh you've seen norm. I have quite a lot of functions so a lot you have like uh to branching to combinator to mount. You can choose multiple functions. Okay, I won't talk about long, so much here yeah, so it works and it's not hard. The only only part I find oh.

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I find it quite easy in fact, except this part, because uh the chrono, what is that chrono right doesn't work with uh chronos, doesn't integrate with tai o3 pyro3 is a python library for no it's a python integration for rus or ffa, or something like that, but it's more than ffi, because you can write like you can write like a titan rust pattern class in rust.

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So uh what it does is I I just lazy to change the this type. This type is. This is the date chrono date type because chrono doesn't have integration with uh pi o3. Yet I'm writing a pr for that, but they don't have integration yet, so I just convert it to string which is uh python date and then and that's why it came out like this yeah temporary. I just put it at so this. This is run in uh python pandas. This part is running python, but this is compound to bite code.

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The only part I find troublesome is because you you can you can put this it's a rust variable. Stock request is the brass variable and this will be converted into the python code.

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And then you have a python object for this, because uh that there isn't a derived for this automatically because they don't know what you want to derive, what type of object you want to derive. So that's why they have this and then all these two pi object then works and you can even convert the title objects to rust using the from pi object, but they have a derived for that. So this is roughly how it looks like using python. So the the it's quite, it's quite straightforward to do this.

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So let's say: if you are missing something, then if you're missing something you you are lazy, then you can just comma to python and then make that I'll choose a python and then just run it here. There's also inline, there's also inline javascript. I I think there's enough javascript as well, but I didn't haven't tried that, but I tried this so far. It's working fine.

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Feel good any questions.

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No should be fine.

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I guess this case that's all for today, so if you guys want to join the call, you can join through the the link show here and we will end the stream now.

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Guys soon in the next meetup.

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