Insert an active model and get back the last insert id doesn't work with autoincrement

[Razzwan]

Description

Insert an active model and get back the last insert id doesn't work with autoincrement id.

Steps to Reproduce

1. Create migration and generate a model

#[derive(Clone, Debug, PartialEq, DeriveEntityModel, Eq)]
#[sea_orm(table_name = "fruit")]
pub struct Model {
    #[sea_orm(primary_key)]
    pub id: i32,
}

2. Insert an active model and get back the last insert id using static method

let pear = fruit::ActiveModel {
    ..Default::default() // just only autoincremented id here
};

let res: InsertResult = Fruit::insert(pear).exec(db).await?;

Expected Behavior

It must insert and return saved id

Actual Behavior

It leads an error:

"Custom Error: Custom Error: Attribute id is NotSet"

Reproduces How Often

All the time

Workarounds

Don't use static method and use such one instead:

let pear = fruit::ActiveModel {
    ..Default::default()
};

let pear: fruit::Model = pear.insert(db).await?;

Reproducible Example

1. Run migration:

use sea_orm_migration::prelude::*;

#[derive(DeriveMigrationName)]
pub struct Migration;

#[async_trait::async_trait]
impl MigrationTrait for Migration {
    async fn up(&self, manager: &SchemaManager) -> Result<(), DbErr> {
        manager
            .create_table(
                Table::create()
                    .table(Fruit::Table)
                    .if_not_exists()
                    .col(
                        ColumnDef::new(Fruit::Id)
                            .integer()
                            .not_null()
                            .auto_increment()
                            .primary_key(),
                    )
                    .to_owned(),
            )
            .await
    }

    async fn down(&self, manager: &SchemaManager) -> Result<(), DbErr> {
        manager
            .drop_table(Table::drop().table(Fruit::Table).to_owned())
            .await
    }
}

#[derive(DeriveIden)]
enum Fruit {
    Table,
    Id,
}

3. Generate a model based on migration above

4. Then try to insert entity using generated model:

let pear = fruit::ActiveModel {
    ..Default::default() // just only autoincremented id here
};

let res: InsertResult = Fruit::insert(pear).exec(db).await?;

Versions

0.12.14