Multiple joins between two tables are not possible

[weiznich]

Given the following two tables:

CREATE TABLE points(
        id BIGSERIAL PRIMARY KEY,
        x DOUBLE PRECISION NOT NULL,
        y DOUBLE PRECISION NOT NULL);

and

CREATE TABLE boxes(
        id BIGSERIAL PRIMARY KEY,
        o BIGINT REFERENCES points(id) NOT NULL,
        u BIGINT REFERENCES points(id) NOT NULL);

I want both relations to be joinable.

infer_table_from_schema!(dotenv!("DATABASE_URL"), "points");
infer_table_from_schema!(dotenv!("DATABASE_URL"), "boxes");

joinable!(boxes -> points (o));
joinable!(boxes -> points (u));

This is currently not possible because the joinable macro is generating a conflicting implementation of the trait JoinTo.

error: conflicting implementations of trait `diesel::JoinTo<points::table, _>` for type `boxes::table`: [--explain E0119]
 --> <diesel macros>:4:1
4 |> impl < JoinType > $ crate :: JoinTo < $ right_table , JoinType > for $
  |> ^

[bpbp-boop]

I just ran into this

table! {
    matches (id) {
        id -> Integer,
        date -> Nullable<Date>,
        time -> Nullable<Time>,
        home_team_id -> Nullable<Integer>,
        away_team_id -> Nullable<Integer>,
    }
}

table! {
    teams (id) {
        id -> Integer,
        name -> Text,
    }
}

joinable!(matches -> teams (home_team_id));
joinable!(matches -> teams (away_team_id));

Have any workaround surfaced since this was opened?

[sgrif]

This is the expected behavior. Otherwise we have no clue what you mean when you say matches.inner_join(teams). You can use the .on method to specify an explicit on clause.