fix: ordering by joined columns for PostgreSQL (#3736)

[antonku]

Description of change

Fixes #3736

This PR adds the missing column to the select clause inside the sub query when ordering is done by a property of a related entity.

Example:

const queryBuilder: SelectQueryBuilder<Photo> = await connection.getRepository(Photo).createQueryBuilder("photo");
await queryBuilder
    .select()
    .leftJoin("photo.user", "user")
    .take(5)
    .orderBy("user.name")
    .getManyAndCount();

Generates the following valid SQL query:

SELECT
	DISTINCT "distinctAlias"."photo_id" AS "ids_photo_id",
	"distinctAlias"."user_name"
FROM
	(
		SELECT "photo"."id" AS "photo_id",
		"photo"."url" AS "photo_url",
		"photo"."userId" AS "photo_userId",
+		"user"."name" AS "user_name" 
	FROM
		"photo" "photo"
	LEFT JOIN "user" "user" ON
		"user"."id" = "photo"."userId") "distinctAlias"
ORDER BY
	"distinctAlias"."user_name" ASC,
	"photo_id" ASC
LIMIT 5

Without the fix "user"."name" AS "user_name" line is missing and query fails with error:

error: column distinctAlias.user_name does not exist

Pull-Request Checklist

• Code is up-to-date with the master branch
• npm run lint passes with this change
• npm run test passes with this change
• This pull request links relevant issues as Fixes #0000
• There are new or updated unit tests validating the change
• Documentation has been updated to reflect this change
• The new commits follow conventions explained in CONTRIBUTING.md

[antonku]

@pleerock Hi! Can you please review this PR?

[pleerock]

Let's hope it won't lead to other issues. Thanks for contribution!

[cjbara]

@pleerock and @antonku, FYI this produces an invalid SQL query if the orderBy is passed in from FindOptions. It can generate a SQL query with trailing commas in the select statement because subquerySelectString can contain empty string values. In this case, the join(", ") adds the trailing commas, producing an invalid SQL query. I just had this issue when I updated my TypeORM version

[antonku]

@cjbara Hi, thank you for the feedback. Can you please provide an example of FindOptions that produces the error?