Why does relations in nestjs-paginate perform a LEFT JOIN even if the related entities are not filtered/selected?

[estevaodias]

Apparently, if you configure your pagination this way, a LEFT JOIN to tags is made even when you request {{baseUrl}}/api/v2/people. Is it intentional to include a relation without specifying filter.tags.name or something similar?

{
  filterableColumns: {
    name: [FilterOperator.EQ, FilterOperator.IN],
    'tags.name': [FilterOperator.EQ, FilterOperator.IN],
  },
  relations: [
    'tags',
  ],
  select: [
    'tags.id',
  ],
}

Here is the output query:

SELECT "__root"."id" AS "__root_id", ... LEFT JOIN "people_tags" ... WHERE "__root"."deleted_at" IS NULL

[Helveg]

If I understand correctly, the tags relationship is indeed always included, because you list it in the relations array. To allow a user to filter on tags.name you don't have to list it there.

AFAIK, if you want to include the relationship only when it's filtered on, then you'll have to inspect the PaginateQuery object, to see if it has the tags.name filter set, and create your relations array accordingly.

The relations array is simply the array of relationships to load on the listed entities.