feat(core): allow specifying custom pivot table entity

[B4nan]

  @ManyToMany({ entity: () => Product, pivotEntity: () => OrderItem })
  products = new Collection<Product>(this);

[codecov-commenter]

Codecov Report

Merging #2901 (8d25d48) into master (f359929) will not change coverage.
The diff coverage is 100.00%.

@@            Coverage Diff            @@
##            master     #2901   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files          193       193           
  Lines        11764     11770    +6     
  Branches      2715      2716    +1     
=========================================
+ Hits         11764     11770    +6     

Impacted Files	Coverage Δ
packages/core/src/decorators/ManyToMany.ts	100.00% <ø> (ø)
packages/core/src/drivers/DatabaseDriver.ts	100.00% <100.00%> (ø)
packages/core/src/metadata/MetadataDiscovery.ts	100.00% <100.00%> (ø)
packages/core/src/metadata/MetadataStorage.ts	100.00% <100.00%> (ø)
packages/core/src/typings.ts	100.00% <100.00%> (ø)
...ges/core/src/unit-of-work/CommitOrderCalculator.ts	100.00% <100.00%> (ø)
packages/knex/src/AbstractSqlDriver.ts	100.00% <100.00%> (ø)
packages/knex/src/query/QueryBuilder.ts	100.00% <100.00%> (ø)
packages/knex/src/query/QueryBuilderHelper.ts	100.00% <100.00%> (ø)

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[yackinn]

Is this supposed to add another column specified in the OrderItem entity to the pivot table?
Can this be used for sorting purposes?

[B4nan]

Full example is in the docs: https://mikro-orm.io/docs/collections#custom-pivot-table-entity

The OrderItem entity represents the pivot table, so yes, it allows you to create additional columns in that table. You can't sort by them from the M:N relation currently, we could allow defining default order by based on that, if you'd like to do it from the FindOptions API, you would need to use the old 1:m - m:1 approach instead as in https://mikro-orm.io/docs/composite-keys#use-case-3-join-table-with-metadata

Or if you can think of some public API that would allow sorting thru the pivot properties, I am not against it, I just don't see how it could be configured.

[yackinn]

If I add the LocationMedium entity to the entiies array it will error.
Error: Please provide either 'type' or 'entity' attribute in LocationMedium.location

If I don't add it to the entities array it doesn't change anything in the pivot table though.

I think that's how it's stated in the docs.

@Entity()
export class LocationMedium {

  @ManyToOne({ primary: true })
  location: Location;

  @ManyToOne({ primary: true })
  medium: Medium;

  @Property({ default: 1 })
  prop: number;

}


// location.entity.ts
@Entity()
export class Location extends OmputBaseEntity {
  @Property()
  title: string;
  ...

  @OneToMany(() => Event, courseDate => courseDate.location, { nullable: true })
  event?: Event[];

  @ManyToMany({ entity: () => Medium, nullable: true, pivotEntity: () => LocationMedium })
  media?: Medium[];
}

[B4nan]

The entity indeed needs to be discovered. You need to specify the type in decorator options (unless you are using ts-morph):

  @ManyToOne(() => Location, { primary: true })
  location: Location;

  @ManyToOne(() => Medium, { primary: true })
  medium: Medium;

Will fix the examples, I am planning to use the code tabs there as well, to show the definition with entity schema as well.

[B4nan]

Note that this is wrong too, you need to use Collection wrapper:

  @OneToMany(() => Event, courseDate => courseDate.location, { nullable: true })
  event?: Event[]; // should be `new Collection<Event>(this)`

  @ManyToMany({ entity: () => Medium, nullable: true, pivotEntity: () => LocationMedium })
  media?: Medium[]; // should be `new Collection<Medium>(this)`

[yackinn]

Thank you.
I should have tried that.

The version without the Collection initilization also works though. The table is update with the new column.

By the way I noticed the search functionality is broken on the 5.1 docs.

[B4nan]

Its not broken, the index needs to be rebuild on algolia after each version is published. It happens once a week, will see if I can trigger it manually.

edit: fixed