Question about complex(?) relationships

[videobitva]

Hello there!

I have been struggling to implement this kind of relationship:

Here is the code which I came up with:

///switch_link.rs:

...

#[derive(Copy, Clone, Debug, EnumIter)]
pub enum Relation {
    SwitchPort,
}


impl RelationTrait for Relation {
    fn def(&self) -> RelationDef {
        match self {
            Self::SwitchPortOne => Entity::belongs_to(super::switch_port::Entity)
                .from((Column::SwitchIdOne, Column::PortIdOne))
                .to((super::switch_port::Column::SwitchId, super::switch_port::Column::PortId))
                .from((Column::SwitchIdTwo, Column::PortIdTwo))
                .to((super::switch_port::Column::SwitchId, super::switch_port::Column::PortId))
                .into(),
        }
    }
}


impl Related<super::switch_port::Entity> for Entity {
    fn to() -> RelationDef {
        Relation::SwitchPort.def()
    }
}

///switch_port.rs:

...


#[derive(Copy, Clone, Debug, EnumIter)]
pub enum Relation {
    SwitchLink,
}


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


impl Related<super::switch_link::Entity> for Entity {
     fn to() -> RelationDef {
         Relation::SwitchLink.def()
     }
}

...

The problem is that if implementing it this way only relationships switch_id_two -> switch_id and port_id_two -> port_id are built.

So my question is: how can I make this work?

Thank you!

[billy1624]

Hey @videobitva, you could use Linked for this.
https://www.sea-ql.org/SeaORM/docs/relation/chained-relations

[videobitva]

Thank you, I tried to look into that. As far as I could understood Linked is used when you already have multiple tables with relations and you want to have a more comfortable way of making joins, am I correct?

[billy1624]

Correct!

[videobitva]

Ok, so my question remains the same: how (or can I even) define both switch_id_one -> switch_id, port_id_one -> port_id and switch_id_two -> switch_id, port_id_two -> port_id? Like, I can't use Linked before I have any relation between switch_port and switch_link defined. Or can I?

UPD: I think I got it, will try to implement it and write it down here if got (or not) any success

[videobitva]

No, I still don't get it.

In order to make relations between switch_link and switch_port I need to implement this thing:

impl Related<super::switch_port::Entity> for Entity {
    fn to() -> RelationDef {
        Relation::SwitchPort.def()
    }
}

but I can't, because in order to do that I need to properly implement this:

impl RelationTrait for Relation {
    fn def(&self) -> RelationDef {
        match self {
            Self::SwitchPort => Entity::belongs_to(super::switch_port::Entity)...
        }
    }
}

[billy1624]

Use Linked trait with https://docs.rs/sea-orm/0.4.2/sea_orm/?search=_linked find_linked methods

[billy1624]

And you can move this code into the Linked def()

Entity::belongs_to(super::switch_port::Entity)
                .from((Column::SwitchIdOne, Column::PortIdOne))
                .to((super::switch_port::Column::SwitchId, super::switch_port::Column::PortId))
                .from((Column::SwitchIdTwo, Column::PortIdTwo))
                .to((super::switch_port::Column::SwitchId, super::switch_port::Column::PortId))
                .into()

[billy1624]

Sorry, gonna sleep now. Let's continue the conversation tmr loll

[videobitva]

Thank you, have a good sleep =)

[isgj]

I see switch_link is related twice with switch_port. AFAIK in SeaORM you can't have 2 relations with an entity. You can try 1 relation and one link or two links.

Here is the link definition for port 2, you can do the same with port 1 or use the relation (enum)

#[derive(Debug)]
pub struct SwitchPortTwo;

impl Linked for SwitchPortTwo {
    type FromEntity = Entity;

    type ToEntity = super::switch_port::Entity;

    fn link(&self) -> Vec<RelationDef> {
        vec![
            Entity::belongs_to(super::switch_port::Entity)
                .from((Column::SwitchIdTwo, Column::PortIdTwo))
                .to((super::switch_port::Column::SwitchId, super::switch_port::Column::PortId))
                .into(),
        ]
    }
}

[billy1624]

Hey @isgj, thanks for the help! Yes, with Linked, you can do so.
Related docs: https://www.sea-ql.org/SeaORM/docs/relation/chained-relations