Enable convert from ActiveModel to Model

[greenhandatsjtu]

PR Info

Related issue: #606

Adds

• Convert from ActiveModel to Model

Changes

[greenhandatsjtu]

Hi, I'm new comer and chose #606 as my first issue to work on. As @billy1624 suggested, I introduce a new trait TryIntoModel and implement it inside derive macros of active model.
Unfortunately, I met several difficulties and don't know how to fix it.

For now, cargo build will fail with 2 kinds of errors like:

error[E0277]: the trait bound `i32: From<sea_query::Value>` is not satisfied
  --> /home/sunhengke/Development/rust/sea-orm/src/tests_cfg/cake_filling_price.rs:17:48
   |
17 | #[derive(Clone, Debug, PartialEq, DeriveModel, DeriveActiveModel)]
   |                                                ^^^^^^^^^^^^^^^^^ the trait `From<sea_query::Value>` is not implemented for `i32`
   |
   = help: the following implementations were found:
             <i32 as From<NonZeroI32>>
             <i32 as From<bool>>
             <i32 as From<i16>>
             <i32 as From<i8>>
           and 86 others
   = note: required because of the requirements on the impl of `Into<i32>` for `sea_query::Value`
   = note: this error originates in the derive macro `DeriveActiveModel` (in Nightly builds, run with -Z macro-backtrace for more info)

error[E0063]: missing field `ignored_attr` in initializer of `cake_filling_price::Model`
  --> /home/sunhengke/Development/rust/sea-orm/src/tests_cfg/cake_filling_price.rs:17:48
   |
17 | #[derive(Clone, Debug, PartialEq, DeriveModel, DeriveActiveModel)]
   |                                                ^^^^^^^^^^^^^^^^^ missing `ignored_attr`
   |
   = note: this error originates in the derive macro `DeriveActiveModel` (in Nightly builds, run with -Z macro-backtrace for more info)

The first error is because Value doesn't implement Into<xxx>, the second error is because the model is:

#[derive(Clone, Debug, PartialEq, DeriveModel, DeriveActiveModel)]
pub struct Model {
    pub id: i32,
    pub name: String,
    pub vendor_id: Option<i32>,
    #[sea_orm(ignore)]
    pub ignored_attr: i32,
}

the field ignored_attr is ignored in ActiveModel, so we can never get the value of ignored_attr when trying to convert ActiveModel back to Model.
I'm not sure about how to handles these errors, what's wrong in my code, and what to do next, so I create this draft PR, would appreciate it if you could give me some advice.
Thanks in advance.

[greenhandatsjtu]

I got an idea for the second err, if there's ignored field in a Model, then we just return DbErr in try_from(), but this may not be a good idea.

For the first err, I'm still not sure what to do. Am I supposed to call functions like is_xxx() and as_ref_xxx() on every Value? It's overwhelming but I can't think of another way

[billy1624]

Hey @greenhandatsjtu, I'm sorry for the delay.

the second error is because the model is: the field ignored_attr is ignored in ActiveModel, so we can never get the value of ignored_attr when trying to convert ActiveModel back to Model.

Ignored fields are assumed to have Default implemented. So, you can simply write Default::default() Just like what we did in DeriveModel procedural macros:

sea-orm/sea-orm-macros/src/derives/model.rs

Lines 113 to 121 in fff738a

	if *ignore {
	quote! {
	Default::default()
	}
	} else {
	quote! {
	row.try_get(pre, sea_orm::IdenStatic::as_str(&<<Self as sea_orm::ModelTrait>::Entity as sea_orm::entity::EntityTrait>::Column::#column_ident).into())?
	}
	}

[billy1624]

The first error is because Value doesn't implement Into<xxx>

I guess we can a.#field.unwrap().unwrap()

[greenhandatsjtu]

Hi @billy1624 , thanks for your advice. I closed this PR because I'm quite busy recently and had no idea on how to handle these errors 😢. Now that you give me some advice, I think it's worthy to give it another try :) I will continue working on this PR in the next few days. Thank you again!

[greenhandatsjtu]

Hi @billy1624 , I just had some free time last weekend and worked on it according to your suggestions, and I think I made it! Thank you so much for guiding me~

[billy1624]

Hey @greenhandatsjtu, sorry for the delay. Could you please add some test cases to test the conversion from ActiveModel to Model?

Better include tests where some model field are annotated with #[sea_orm(ignore)].
https://www.sea-ql.org/SeaORM/docs/generate-entity/entity-structure/#ignore-attribute

Many thanks!!

[greenhandatsjtu]

Hey @billy1624 , sure I will add some tests. However, I need some instructions on following two problems:

• I noticed that one of the CI tests failed, but I can't figure out what's wrong with my code :(
• Where to put these test cases in, and what to test? Should I write tests like below:

#[derive(Clone, Debug, PartialEq, DeriveModel, DeriveActiveModel)]
pub struct Model {
    pub id: i32,
    pub name: String,
}

let pineapple = ActiveModel {
    id: Set(1),
    name: Set("Pineapple".to_owned()),
};
let model: Model = pineapple.try_into_model().unwrap();
assert_eq!(model.id, 1);
assert_eq!(model.name, "Pineapple".to_owned());

I would appreciate it if you could give me some advice!

[billy1624]

Hey @greenhandatsjtu, if you execute cargo expand command. You will see:

#[automatically_derived]
impl std::convert::TryFrom<ActiveModel> for <Entity as EntityTrait>::Model {
    type Error = DbErr;
    fn try_from(a: ActiveModel) -> Result<Self, DbErr> {
        if match a.id {
            sea_orm::ActiveValue::NotSet => true,
            _ => false,
        } {
            return Err(DbErr::Custom({
                let res = ::alloc::fmt::format(::core::fmt::Arguments::new_v1(
                    &["field ", " is NotSet"],
                    &[::core::fmt::ArgumentV1::new_display(&"id")],
                ));
                res
            }));
        }
        if match a.name {
            sea_orm::ActiveValue::NotSet => true,
            _ => false,
        } {
            return Err(DbErr::Custom({
                let res = ::alloc::fmt::format(::core::fmt::Arguments::new_v1(
                    &["field ", " is NotSet"],
                    &[::core::fmt::ArgumentV1::new_display(&"name")],
                ));
                res
            }));
        }
        Ok(Self {
            id: a.id.into_value().unwrap().unwrap(),
            name: a.name.into_value().unwrap().unwrap(),
        })
    }
}
#[automatically_derived]
impl sea_orm::TryIntoModel<<Entity as EntityTrait>::Model> for ActiveModel {
    fn try_into_model(self) -> Result<<Entity as EntityTrait>::Model, DbErr> {
        self.try_into()
    }
}

When converting from ActiveModel to Model. A field is missing.

Ok(Self {
    id: a.id.into_value().unwrap().unwrap(),
    name: a.name.into_value().unwrap().unwrap(),
    // `cake_id` is missing here
})

---

EDIT: I fixed the error on #975. I consider it's a misuse of DeriveActiveModel that cause the error.

[billy1624]

• Where to put these test cases in, and what to test? Should I write tests like below:

#[derive(Clone, Debug, PartialEq, DeriveModel, DeriveActiveModel)]
pub struct Model {
    pub id: i32,
    pub name: String,
}

let pineapple = ActiveModel {
    id: Set(1),
    name: Set("Pineapple".to_owned()),
};
let model: Model = pineapple.try_into_model().unwrap();
assert_eq!(model.id, 1);
assert_eq!(model.name, "Pineapple".to_owned());

You can put test under here:

sea-orm/src/entity/active_model.rs

Line 841 in d262501

mod tests {

Basically, we want to test the success and fail cases. Also the special case, where some fields are being ignored.

[greenhandatsjtu]

Hi @billy1624 , thanks for your guidance, I've add some tests for converting from ActiveModel to Model, please review :)

[billy1624]

Hey @greenhandatsjtu, the test cases looks nice!

I'd like to refactor the code, please check greenhandatsjtu#1

[greenhandatsjtu]

Hi @billy1624 , the PR looks good to me and I've merged it, thanks!

[billy1624]

Hey @greenhandatsjtu, thanks again for the contributions!

I will merge this into a working branch and do a rebase before it'll be merged into master. :)