evoluJsonObjectFrom - API reference

API reference › @evolu/common › local‑first/Query › evoluJsonObjectFrom

function evoluJsonObjectFrom<O>(
  expr: SelectQueryBuilderExpression<O>,
): RawBuilder<Simplify<O> | null>;

Defined in: packages/common/src/local-first/Query.ts:224

An improved Evolu version of Kysely's SQLite jsonObjectFrom helper.

Kysely's ParseJSONResultsPlugin heuristically parses any result string that looks like JSON. Evolu instead prefixes JSON produced by these helpers with a per-runtime identifier and only parses values carrying that prefix, avoiding accidental parsing of ordinary string columns that merely happen to start with { or [.

The subquery must only return one row.

Example

import {
  createQueryBuilder,
  evoluJsonObjectFrom,
  id,
  NonEmptyTrimmedString100,
  SqliteBoolean,
} from "@evolu/common";

const PersonId = id("Person");
const Schema = {
  person: { id: PersonId },
  pet: {
    id: id("Pet"),
    name: NonEmptyTrimmedString100,
    personId: PersonId,
    isFavorite: SqliteBoolean,
  },
};
const createQuery = createQueryBuilder(Schema);
const people = createQuery((db) =>
  db
    .selectFrom("person")
    .select(["person.id"])
    .select((eb) => [
      evoluJsonObjectFrom(
        eb
          .selectFrom("pet")
          .select(["pet.id as petId", "pet.name"])
          .whereRef("pet.personId", "=", "person.id")
          .where("pet.isFavorite", "=", 1),
      ).as("favoritePet"),
    ]),
);

expectTypeOf<typeof people.Row.favoritePet>().toEqualTypeOf<{
  petId: typeof Schema.pet.id.Output;
  name: NonEmptyTrimmedString100 | null;
} | null>();