How can I left-join query with TypeOrm

Issue type:

[x] question [ ] bug report [ ] feature request [ ] documentation issue

Database system/driver:

[ ] cordova [ ] mongodb [ ] mssql [ ] mysql / mariadb [ ] oracle [x] postgres [ ] cockroachdb [ ] sqlite [ ] sqljs [ ] react-native [ ] expo

TypeORM version:

[x] latest [ ] @next [ ] 0.x.x (or put your version here)

Steps to reproduce or a small repository showing the problem: There are some tables:

CREATE TABLE a (
  a_id serial PRIMARY KEY,
  name text
);

CREATE TABLE b (
  a_id integer REFERENCES a (a_id),
  name text
);

CREATE TABLE c (
  a_id integer REFERENCES a (a_id),
  name text
);

And then I want to query something like this:

SELECT * FROM a
LEFT JOIN b USING (a_id)
LEFT JOIN c USING (a_id)
;

How do I query above with TypeOrm?

[Flusinerd]

Try adding this decorator to your a-model

@OneToMany( type =>BDbModel, b => b.a)
b!: BDbModel[];

I think the error is because it cannot find the relation (Only defined from b-side not from the a-side)

Then you should be able to do the following:

.leftJoinAndSelect('a.b', 'b',)

Thats how I do it.

[resotto]

@Flusinerd Thank you for your fast replying. I just tried QueryBuilder with something like this:

import { Entity, PrimaryGeneratedColumn, Column } from 'typeorm';
import { BDbModel } from './b.entity';

@Entity({ schema: 'public', name: 'a' })
export class ADbModel {
  @PrimaryGeneratedColumn({ name: 'a_id' })
  id!: number;

  @Column({ type: 'text' })
  name!: string;

  b!: BDbModel;
}

import { Entity, ManyToOne, JoinColumn, Column } from 'typeorm';
import { ADbModel } from './a.entity';

@Entity({ schema: 'public', name: 'b' })
export class BDbModel {
  @ManyToOne(() => ADbModel, { primary: true })
  @JoinColumn({ name: 'a_id' })
  a!: ADbModel;

  @Column({ type: 'text' })
  name!: string;
}

  const aDbModel = await conn
    .getRepository(ADbModel)
    .createQueryBuilder('a')
    .leftJoinAndSelect('b', 'b', 'b.a_id = a.a_id')
    .where('a.id = :id', { id: 1 })
    .getRawOne();
  // .getOne();

When I used .getOne(), I couldn’t get the value of b.name in return value. When I used .getRawOne(), I could get the value in return value, but type of return value was just object, not ADbModel (entity of a).

So could I get the value of b.name with ADbModel (entity type)?