The derive macro DeriveRelation does not generate Related trait for entity. Is this normal ?

[leo91000]

I was following the doc to create a one to many relationship. When I use manual trait implementation, it works fine. However, when I'm using the macro way with DeriveRelation, it doesn't generate the Related (only the RelationTrait is generated) trait, is this normal or I'm having a bug ?

[billy1624]

Hey @leo91000, welcome and thanks for asking. DeriveRelation does not generate Related implementation for you. Take this for an example, it only implements RelationTrait for you.

The DeriveRelation macro is a simple wrapper to impl the RelationTrait.

#[derive(DeriveRelation)]
pub enum Relation {
    #[sea_orm(has_many = "super::fruit::Entity")]
    Fruit,
}

expands into

impl RelationTrait for Relation {
    fn def(&self) -> RelationDef {
        match self {
            Self::Fruit => Entity::has_many(super::fruit::Entity).into(),
        }
    }
}

https://www.sea-ql.org/SeaORM/docs/generate-entity/entity-structure#relation

[LasseRosenow]

Would it be technically possible to extend it to also generate the Related stuff? That would be sooo handy :O

[tyt2y3]

Perhaps we can have a proc macro and a DSL, although I don't like DSLs too much

related!(cake::Entity -> cake_filling::Relation::Cake.def().rev() -> cake_filling::Relation::Filling.def() -> fruit::Entity);

in place of

impl Related<super::filling::Entity> for Entity {
    fn to() -> RelationDef {
        super::cake_filling::Relation::Filling.def()
    }

    fn via() -> Option<RelationDef> {
        Some(super::cake_filling::Relation::Cake.def().rev())
    }
}

Does that actually make it more readable / understandable / easier to write?