MutationKey | TanStack Query Solid Docs

type MutationKey = Register extends object ? TMutationKey extends ReadonlyArray<unknown> ? TMutationKey : TMutationKey extends unknown[] ? TMutationKey : ReadonlyArray<unknown> : ReadonlyArray<unknown>;

Defined in: packages/query-core/src/types.ts:1808

The type of a mutation key — the serializable array used to identify and filter mutations. Defaults to ReadonlyArray<unknown>; declare mutationKey on Register to narrow it repository-wide.