TypeORM: how to load relations with CreateQueryBuilder, without using JOINs?

Question

I'm developing an API using NestJS & TypeORM to fetch data from a MySQL DB. Currently I'm trying to get all the instances of an entity (HearingTonalTestPage) and all the related entities (e.g. Frequency). I can get it using createQueryBuilder:

const queryBuilder = await this.hearingTonalTestPageRepo
      .createQueryBuilder('hearing_tonal_test_page')
      .innerJoinAndSelect('hearing_tonal_test_page.hearingTest', 'hearingTest')
      .innerJoinAndSelect('hearingTest.page', 'page')
      .innerJoinAndSelect('hearing_tonal_test_page.frequencies', 'frequencies')
      .innerJoinAndSelect('frequencies.frequency', 'frequency')
      .where(whereConditions)
      .orderBy(`page.${orderBy}`, StringToSortType(pageFilterDto.ascending));

The problem here is that this will produce a SQL query (screenshot below) which will output a line per each related entity (Frequency), when I want to output a line per each HearingTonalTestPage (in the screenshot example, 3 rows instead of 12) without losing its relations data. Reading the docs, apparently this can be easily achieved using the relations option with .find(). With QueryBuilder I see some relation methods, but from I've read, under the hood it will produce JOINs, which of course I want to avoid.

So the 1 million $ question here is: is it possible with CreateQueryBuilder to load the relations after querying the main entities (something similar to .find({ relations: { } }) )? If yes, how can I achieve it?

Answer 1

I am not an expert, but I had a similar case and using:

const qb = this.createQueryBuilder("product");
        
// apply relations
FindOptionsUtils.applyRelationsRecursively(qb, ["createdBy", "updatedBy"], qb.alias, this.metadata, "");

return qb
    .orderBy("product.id", "DESC")
    .limit(1)
    .getOne();

it worked for me, all relations are correctly loaded.

ref: https://github.com/typeorm/typeorm/blob/master/src/find-options/FindOptionsUtils.ts