Kysely•3mo ago

Query fragmentation causes typing to break

Hi, can anybody help how to make fragmented joins working? https://kyse.link/SVDlH

let query_ok = db
  .selectFrom("person")
  .innerJoin("pet", "owner_id", "person.id");
query_ok = query_ok.innerJoin("toy", "toy.pet_id", "pet.id");

let query_ok = db
  .selectFrom("person")
  .innerJoin("pet", "owner_id", "person.id");
query_ok = query_ok.innerJoin("toy", "toy.pet_id", "pet.id");

let query_fails = db.selectFrom("person");
query_fails = query_fails.innerJoin("pet", "owner_id", "person.id");
query_fails = query_fails.innerJoin("toy", "toy.pet_id", "pet.id"); // Argument of type '"pet.id"' is not assignable to parameter of type 'AnyJoinColumn<Database, "person", "toy"> | AnyJoinColumnWithTable<Database, "person", "toy">'.(2345)

let query_fails = db.selectFrom("person");
query_fails = query_fails.innerJoin("pet", "owner_id", "person.id");
query_fails = query_fails.innerJoin("toy", "toy.pet_id", "pet.id"); // Argument of type '"pet.id"' is not assignable to parameter of type 'AnyJoinColumn<Database, "person", "toy"> | AnyJoinColumnWithTable<Database, "person", "toy">'.(2345)

16 Replies

Unknown User•3mo ago

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mikeOP•3mo ago

ok, ... 🙂 solid workaround in such a case those can be constants 🙂 of course not with conditional if statements

Unknown User•3mo ago

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mikeOP•3mo ago

So conditional builder would look like this? is this the best way how to do it? https://kyse.link/toaW0

koskimas•3mo ago

Variable types can never become wider in typescript. When you join a table, the new query builder's type is wider (contains the information about the joined table). When you assign it to the old variable, the old variable's type doesn't (and can't) change. So you need to assign the result of a join to a new variable if you want to keep the new wider type. There's no way around it.

So conditional builder would look like this? is this the best way how to do it?

That doesn't work either. The type of the resulting query builder is the same as the original one.

mikeOP•3mo ago

testing https://kysely.dev/docs/recipes/deduplicate-joins now if does (hopefully) what i need

Deduplicate joins | Kysely

When building dynamic queries, you sometimes end up in situations where the same join

Igal (mobile)•3mo ago

There might be a way to widen variable types. A noop (arg: unknown): asserts arg is WiderType function call. Needs investigation for the generic case.

koskimas•3mo ago

Nope, it just narrows it

koskimas•3mo ago

A better example

Igal (mobile)•3mo ago

I have an example somewhere in which it is not the case. where you can pretty much decorate an object with extra properties

koskimas•3mo ago

An object with more properties is narrower A more specific interface. Less options fit it & narrows | widens That's what happens in my first example as well

Igal (mobile)•3mo ago

you can also apply a union..

koskimas•2mo ago

If you apply a union, it will narrow the type with the union. It doesn't union anything to the original type.

koskimas•2mo ago

asserts x is T will always just set (typeof x) & T as the type

Igal•2mo ago

Sorry, confused the lingo. Anyway, This is possible:

import { Selectable, SelectQueryBuilder } from 'kysely'

interface DB {
    person: {
        id: string;
    }
    pet: {
        id: string;
        owner_id: string | null;
    }
}

let thing = null as unknown as SelectQueryBuilder<DB, 'person', Selectable<DB['person']>>

assertUnion(thing)

thing
// ^? SelectQueryBuilder<DB, "person" | "pet", ...>

function assertUnion(_x: unknown): asserts _x is SelectQueryBuilder<DB, 'pet' | 'person', Selectable<DB['person']> & Selectable<DB['pet']>> {
    // noop
}

import { Selectable, SelectQueryBuilder } from 'kysely'

interface DB {
    person: {
        id: string;
    }
    pet: {
        id: string;
        owner_id: string | null;
    }
}

let thing = null as unknown as SelectQueryBuilder<DB, 'person', Selectable<DB['person']>>

assertUnion(thing)

thing
// ^? SelectQueryBuilder<DB, "person" | "pet", ...>

function assertUnion(_x: unknown): asserts _x is SelectQueryBuilder<DB, 'pet' | 'person', Selectable<DB['person']> & Selectable<DB['pet']>> {
    // noop
}

https://tsplay.dev/wE9Q3w It's wider in the sense that, there's a wider query context now.

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Query fragmentation causes typing to break

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