add `prefix` support to `FromQueryResult` `nested` attribute

[YouKnow-sys]

Motivation

Right now as far as I can see there's no way to add prefix to a nested model, not having this feautre stops us from using/nseting the same model multiple times inside same model.

Proposed Solutions

We should add support for setting prefix key inside the nested attribute, so user can do #[sea_orm(nested(prefix = "player_"))] or maybe if just #[sea_orm(nested(prefix))] we can prefix the nested model with the variable name that it's set to...

[sinder38]

Why not join with alias?
docs: https://www.sea-ql.org/SeaORM/docs/relation/nested-selects/#nested-fromqueryresult

#[derive(DerivePartialModel)]
#[sea_orm(entity = "cake::Entity")]
struct CakeFactory {
    id: i32,
    name: String,
    #[sea_orm(nested, alias = "factory")] //<- Look heree
    bakery: Option<Factory>,
}

#[derive(DerivePartialModel)]
#[sea_orm(entity = "bakery::Entity")]
struct Factory {
    id: i32,
    #[sea_orm(from_col = "name")]
    plant: String,
}

let cake_factory: CakeFactory = cake::Entity::find()
    .join_as(
        JoinType::LeftJoin,
        cake::Relation::Bakery.def(),
        "factory",
    )
    .order_by_asc(cake::Column::Id)
    .into_partial_model()
    .one(db)
    .await?
    .unwrap();

[YouKnow-sys]

Why not join with alias? docs: https://www.sea-ql.org/SeaORM/docs/relation/nested-selects/#nested-fromqueryresult

#[derive(DerivePartialModel)]
#[sea_orm(entity = "cake::Entity")]
struct CakeFactory {
id: i32,
name: String,
#[sea_orm(nested, alias = "factory")] //<- Look heree
bakery: Option,
}

#[derive(DerivePartialModel)]
#[sea_orm(entity = "bakery::Entity")]
struct Factory {
id: i32,
#[sea_orm(from_col = "name")]
plant: String,
}

let cake_factory: CakeFactory = cake::Entity::find()
.join_as(
JoinType::LeftJoin,
cake::Relation::Bakery.def(),
"factory",
)
.order_by_asc(cake::Column::Id)
.into_partial_model()
.one(db)
.await?
.unwrap();

my use case is like this

#[derive(sea_orm::FromQueryResult)]
pub struct CardsInfo {
    pub bought_with_balance: i64,
    pub bonus: i64,
}

#[derive(sea_orm::FromQueryResult)]
pub struct PlayersAndCardsCount {
    pub players: i64,
    #[sea_orm(nested)]
    pub cards: CardsInfo,
    #[sea_orm(nested)]
    pub player_cards: CardsInfo,
}

so as you can see I have a model that used another nested models too time... not sure if your solution works here as the fields are calculated in query

[sinder38]

Again, this example is with PartialModel and not QueryResult.
I honestly prefer PartialModel over QueryResult
These no example with QueryResult in the codebase

Example:

sea-orm/tests/partial_model_nested/nested_alias.rs

Lines 8 to 25 in be447aa

	#[derive(DerivePartialModel)]
	#[sea_orm(entity = "worker::Entity")]
	struct Worker {
	id: i32,
	name: String,
	}
	#[derive(DerivePartialModel)]
	#[sea_orm(entity = "bakery::Entity")]
	struct BakeryWorker {
	id: i32,
	name: String,
	profit_margin: f64,
	#[sea_orm(nested, alias = "manager")]
	manager: Worker,
	#[sea_orm(nested, alias = "cashier")]
	cashier: worker::Model,
	}

[YouKnow-sys]

I mean isn't FromQueryResult the right way to do what I want here? again as I said I'm not just fetching data from database, Im calculating them using Func::sum and other things... so Im not sure how PartialModel can be used in this case

[sinder38]

You didn't tell me you are doing calculation, it looked like normal entities to me.
Okay, now I see the problem, multiple actually.

1. Yes, this feature is needed
2. FromQueryResult macros silently fails

You probably know this, but while this feature is not available you can do this, but with your Player Card thingy:

/// Nested result for a worker joined under the "manager_*" alias prefix.
#[derive(Debug, PartialEq, FromQueryResult)]
struct ManagerWorker {
    #[sea_orm(from_alias = "manager_id")]
    id: i32,
    #[sea_orm(from_alias = "manager_name")]
    name: String,
}

/// Nested result for a worker joined under the "cashier_*" alias prefix.
#[derive(Debug, PartialEq, FromQueryResult)]
struct CashierWorker {
    #[sea_orm(from_alias = "cashier_id")]
    id: i32,
    #[sea_orm(from_alias = "cashier_name", lalala)]
    name: String,
}

[YouKnow-sys]

• Yes, this feature is needed
• FromQueryResult macros silently fails

Good points... there should be an error when user tries to use same model multiple times without a prefix (that we dont have right now)
I can implement this feature, should I go ahead, or are you already working on it?

[sinder38]

I am waiting for review on my current PRs and issues, so go ahead. I would have started to implement this only after I've done my existing ones

[tyt2y3]

@sinder38 sorry but I sometimes miss draft PRs. if you think they're ready to review, can you convert the status?

[sinder38]

@tyt2y3
Okay, I will mark them as ready.
Sorry, I just marked them as draft because I am used to treat Draft as not ready for actual merge. I just need clarifications on design to continue working