Knex typescript fails with joins

[aliosman21]

Environment

Knex version: 2.0.0
Postgres+ 12.11:
OS: Windows

Questions about how to use knex

I am trying to use Knex and inspect the types of the result so for instance

const entries = await trx<Table_Type>('table')
			.select(
				trx.ref('id').withSchema('table'),
				trx.ref('name').withSchema('table'),
			)

The entries type is correct for each column selected.

But once I try to make a join like this

.leftJoin<Table2_Type>('table2', 'table.id', 'table2.table1_id')

All types are marked as never, am I missing something ?

[joshkel]

Are you augmenting the Table interface, as described at https://knexjs.org/guide/#typescript?

The type definitions, overloads, and inferences necessary to make leftJoin work are quite complicated, and manually specifying a type as in .leftJoin<Table2_Type> may confuse it. However, if you augment the Table interface and let TypeScript + Knex infer the appropriate generic types itself, it ought to work. (At least, it does for my project.)

[aliosman21]

Yes, I do augment the table interface with all new tables.

Just note my original query is quite a lengthy one with multiple joins, for a few joins type is inferred correctly but after some more joins it just doesn't infer it anymore.

[owlas]

I've also noticed the types change depending on the order of the columns in the join ON clause:

await knex('a').innerJoin('b', 'a.id', 'b.id')
// type is (A & B)

await ('a').innerJoin('b', 'b.id', 'a.id')
// type is (A | (A & B))