diff --git a/site/docs/recipes/0001-relations.md b/site/docs/recipes/0001-relations.md index e74fec06e..5663caf3f 100644 --- a/site/docs/recipes/0001-relations.md +++ b/site/docs/recipes/0001-relations.md @@ -78,16 +78,12 @@ Simple right 😅. Yeah, not so much. But it does provide full control over the Fortunately we can improve and simplify this a lot using Kysely. First let's define a couple of helpers: ```ts -function jsonArrayFrom( - expr: Expression -): RawBuilder[]> { - return sql`(select coalesce(json_agg(agg), '[]') from ${expr} as agg)` +function jsonArrayFrom(expr: Expression) { + return sql[]>`(select coalesce(json_agg(agg), '[]') from ${expr} as agg)` } -export function jsonObjectFrom( - expr: Expression -): RawBuilder> { - return sql`(select to_json(obj) from ${expr} as obj)` +function jsonObjectFrom(expr: Expression) { + return sql>`(select to_json(obj) from ${expr} as obj)` } ``` @@ -132,27 +128,27 @@ const persons = await db .execute() console.log(persons[0].pets[0].name) -console.log(persons[0].mother.first_name) +console.log(persons[0].mother?.first_name) ``` That's better right? If you need to do this over and over in your codebase, you can create some helpers like these: ```ts -function withPets(eb: ExpressionBuilder) { +function pets(ownerId: Expression) { return jsonArrayFrom( - eb.selectFrom('pet') + db.selectFrom('pet') .select(['pet.id', 'pet.name']) - .whereRef('pet.owner_id', '=', 'person.id') + .where('pet.owner_id', '=', ownerId) .orderBy('pet.name') - ).as('pets') + ) } -function withMom(eb: ExpressionBuilder) { +function mother(motherId: Expression) { return jsonObjectFrom( - eb.selectFrom('person as mother') + db.selectFrom('person as mother') .select(['mother.id', 'mother.first_name']) - .whereRef('mother.id', '=', 'person.mother_id') - ).as('mother') + .where('mother.id', '=', motherId) + ) } ``` @@ -162,9 +158,27 @@ And now you get this: const persons = await db .selectFrom('person') .selectAll('person') - .select((eb) => [ - withPets(eb), - withMom(eb) + .select(({ ref }) => [ + pets(ref('person.id')).as('pets'), + mother(ref('person.mother_id')).as('mother') + ]) + .execute() + +console.log(persons[0].pets[0].name) +console.log(persons[0].mother?.first_name) +``` + +In some cases Kysely marks your selections as nullable if it's not able to know the related object +always exists. If you have that information, you can mark the relation non-null using the +`$notNull()` helper like this: + +```ts +const persons = await db + .selectFrom('person') + .selectAll('person') + .select(({ ref }) => [ + pets(ref('person.id')).as('pets'), + mother(ref('person.mother_id')).$notNull().as('mother') ]) .execute() @@ -178,7 +192,11 @@ If you need to select relations conditionally, `$if` is your friend: const persons = await db .selectFrom('person') .selectAll('person') - .$if(includePets, (qb) => qb.select(withPets)) - .$if(includeMom, (qb) => qb.select(withMom)) + .$if(includePets, (qb) => qb.select( + (eb) => pets(eb.ref('person.id')).as('pets') + )) + .$if(includeMom, (qb) => qb.select( + (eb) => mother(eb.ref('person.mother_id')).as('mother') + )) .execute() ```