Design and implement the Bakery Chain schema

[samsamai]

This PR implements the example schema for the entities in the Bakery Chain domain and adds basic tests for the creation of these tables.

[tyt2y3]

Thank you. Seems good so far.

One thing. We can use

db.get_query_builder_backend()

in place of SqliteQueryBuilder to make it backend agnostic.

[tyt2y3]

Can you paste the latest ER diagram here again?

[samsamai]

[tyt2y3]

One problem. Isn't the many side of the Cake - LineItem relation in the wrong place?
Shouldn't it be line_item.cake_id = cake.id
Such that one cake can appear in many orders?

[samsamai]

Yes, I see what you mean. I started looking at Cake as a unique product when I added the 'best before', 'produced at' etc fields.
Cake should probably more general like "Chocolate Cake" and we could have X number of chocolate cakes available. But then what to do with the date/timestamp fields?

[samsamai]

Maybe the date/timestamp fields can go on the lineitem

[samsamai]

[tyt2y3]

We might switch to Decimal on prices once SeaQL/sea-query#67 is done.

[tyt2y3]

Please use sea_query's NaiveDateTime support on timestamp.

[samsamai]

@tyt2y3 when I use NaiveDateTime from chrono
pub placed_at: NaiveDateTime,

I get the following errors about the trait bounds not satisfied:

   Compiling sea-orm v0.1.0 (/Users/sam/Code/github/sea-orm)
error[E0277]: the trait bound `NaiveDateTime: std::default::Default` is not satisfied
  --> tests/bakery_chain/order.rs:20:48
   |
20 | #[derive(Clone, Debug, PartialEq, DeriveModel, DeriveActiveModel)]
   |                                                ^^^^^^^^^^^^^^^^^ the trait `std::default::Default` is not implemented for `NaiveDateTime`
   |
  ::: /Users/sam/Code/github/sea-orm/src/entity/active_model.rs:10:22
   |
10 |     V: Into<Value> + Default,
   |                      ------- required by this bound in `ActiveValue`
   |
   = note: this error originates in a derive macro (in Nightly builds, run with -Z macro-backtrace for more info)

error: aborting due to previous error

For more information about this error, try `rustc --explain E0277`.
error: could not compile `sea-orm`

To learn more, run the command again with --verbose.

[tyt2y3]

732428f
I removed the Default bound from the trait ActiveValue
Should be okay now?

[samsamai]

@tyt2y3 it's getting further now but there are still some issues. Please see the this branch: https://github.com/SeaQL/sea-orm/tree/nativedatetime

and test using:

cargo test --test bakery_chain_tests -- --nocapture

[tyt2y3]

Still need help on this? Or you can learn from what I did on Decimal support?

[tyt2y3]

Thank you. Looks fine so far. Please continue. But I also want to use more data types of 'sea_query::Value' so as to make the coverage more complete.

[tyt2y3]

Nice. Have you tried running it against a MySQL instance?

[tyt2y3]

SeaQL/sea-query#67
Decimal support added

[samsamai]

SeaQL/sea-query#67
Decimal support added

With regards to using Decimal for our prices, would our model look something like this:

#[derive(Clone, Debug, PartialEq, DeriveModel, DeriveActiveModel)]
pub struct Model {
    pub id: i32,
    pub price: Decimal,
    pub quantity: i32,
    pub order_id: Option<i32>,
    pub cake_id: Option<i32>,
}

If so where is Decimal coming from? Directly from rust_decimal or through SeaQuery?
Coming directly from rust_decimal I ran into some issues with traits:

error[E0277]: the trait bound `sea_orm::Value: From<rust_decimal::Decimal>` is not satisfied
  --> tests/bakery_chain/lineitem.rs:13:48
   |
13 | #[derive(Clone, Debug, PartialEq, DeriveModel, DeriveActiveModel)]
   |                                                ^^^^^^^^^^^^^^^^^ the trait `From<rust_decimal::Decimal>` is not implemented for `sea_orm::Value`
   |
  ::: /Users/sam/Code/github/sea-orm/src/entity/active_model.rs:10:8
   |
10 |     V: Into<Value>,
   |        ----------- required by this bound in `ActiveValue`
   |

Or do we just use f64 in the model?

[tyt2y3]

Sorry I forgot to impl that trait.
The Decimal should come from rust_decimal.
Now added SeaQL/sea-query@dcd27d4#diff-be1c878c753064b7eaddf4a10ba4215a93dd1817d31e6788691cdb29752fd612R620
Note: you need to upgrade your local sea-query to 0.12.5

[tyt2y3]

I have fixed the build errors.
But then I discovered that sqlx with SQLite does not support deserializing to Decimal
So we can only run the test suite on MySQL & Postgres.
Edit: I tried to support Decimal on SQLite

[tyt2y3]

Nice. I am glad we made it work now!

[samsamai]

Nice. I am glad we made it work now!

Thank you!

[tyt2y3]

How about NaiveDateTime, are you also trying?

[samsamai]

How about NaiveDateTime, are you also trying?

@tyt2y3 I was getting this:

   Compiling sea-orm v0.1.0 (/Users/sam/Code/github/sea-orm)
error[E0277]: the trait bound `NaiveDateTime: std::default::Default` is not satisfied
   --> tests/bakery_chain/order.rs:14:48
    |
14  | #[derive(Clone, Debug, PartialEq, DeriveModel, DeriveActiveModel)]
    |                                                ^^^^^^^^^^^^^^^^^ the trait `std::default::Default` is not implemented for `NaiveDateTime`
    |
   ::: /Users/sam/.rustup/toolchains/stable-x86_64-apple-darwin/lib/rustlib/src/rust/library/core/src/mem/mod.rs:761:16
    |
761 | pub fn take<T: Default>(dest: &mut T) -> T {
    |                ------- required by this bound in `std::mem::take`
    |
    = note: required because of the requirements on the impl of `std::default::Default` for `ActiveValue<NaiveDateTime>`
    = note: this error originates in a derive macro (in Nightly builds, run with -Z macro-backtrace for more info)

error: aborting due to previous error

For more information about this error, try `rustc --explain E0277`.
error: could not compile `sea-orm`

To learn more, run the command again with --verbose.

So I've made placed_at: pub placed_at: Option<NaiveDateTime>,

[tyt2y3]

okay so, I think the problem is you merged wrongly.
It's getting hard to untangle now.
Let me merge it first.

[tyt2y3]

It should be fine if we branch off again from master and add in NaiveDateTime now.
Thank you for now.