Associations or joinable! probleams

[fundon]

Setup

Versions

• Rust: 1.26.1
• Diesel: 1.3.1
• Database: postgres 10.4
• Operating System macOS 10.13.4

Feature Flags

• diesel:

diesel = { version = "1.3", default-features = false, features = ["chrono", "postgres", "r2d2", "serde_json"] }

Problem Description

up.sql

CREATE TABLE leagues (
  id SERIAL PRIMARY KEY,
  name VARCHAR(255) NOT NULL
};

CREATE TABLE IF NOT EXISTS teams (
  id SERIAL PRIMARY KEY,
  name VARCHAR(255) UNIQUE NOT NULL,
  league_id INTEGER NOT NULL REFERENCES leagues (id)
};

CREATE TABLE IF NOT EXISTS matches (
  id SERIAL PRIMARY KEY,
  home_id INTEGER NOT NULL REFERENCES teams (id),
  away_id INTEGER NOT NULL REFERENCES teams (id),
  league_id INTEGER NOT NULL REFERENCES leagues (id)
};

schema.rs

table! {
    leagues (id) {
        id -> Int4,
        name -> Varchar,
    }
}

table! {
    matches (id) {
        id -> Int4,
        home_id -> Int4,
        away_id -> Int4,
        league_id -> Int4,
    }
}

table! {
    teams (id) {
        id -> Int4,
        name -> Varchar,
        league_id -> Int4,
    }
}

joinable!(matches -> leagues (league_id));
joinable!(teams -> leagues (league_id));

allow_tables_to_appear_in_same_query!(
    leagues,
    matches,
    teams,
);

What are you trying to accomplish?

not found

joinable!(matches -> teams (home_id));
joinable!(matches -> teams (away_id));

then, I add them to the schema.rs

What is the expected output?

What is the actual output?

Are you seeing any additional errors?

error[E0119]: conflicting implementations of trait `diesel::JoinTo<models::schema::teams::table>` for type `models::schema::matches::table`:
  --> src/models/schema.rs:73:1
   |
72 | joinable!(matches -> teams(home_id));
   | ------------------------------------- first implementation here
73 | joinable!(matches -> teams(away_id));
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ conflicting implementation for `models::schema::matches::table`
   |
   = note: this error originates in a macro outside of the current crate (in Nightly builds, run with -Z external-macro-backtrace for more info)

error[E0119]: conflicting implementations of trait `diesel::JoinTo<models::schema::matches::table>` for type `models::schema::teams::table`:
  --> src/models/schema.rs:73:1
   |
72 | joinable!(matches -> teams(home_id));
   | ------------------------------------- first implementation here
73 | joinable!(matches -> teams(away_id));
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ conflicting implementation for `models::schema::teams::table`
   |
   = note: this error originates in a macro outside of the current crate (in Nightly builds, run with -Z external-macro-backtrace for more info)

error: aborting due to 2 previous errors

For more information about this error, try `rustc --explain E0119`.
error: Could not compile `server`.

To learn more, run the command again with --verbose.

Steps to reproduce

Checklist

• I have already looked over the issue tracker for similar issues.
• This issue can be reproduced on Rust's stable channel. (Your issue will be
  closed if this is not the case)

[sgrif]

Quoting the docs for joinable!

Allow two tables to be referenced in a join query without providing an explicit ON clause.

The only affect this macro has is decides what ON clause is used when you do left_table.inner_join(right_table). We can't have two implementations of that for the same two tables, the compiler doesn't know what you meant. You will need to provide the on clause explicitly.