upstream-tanstack-query/docs/framework/angular/reference/interfaces/BaseMutationNarrowing.md

id, title

id	title
BaseMutationNarrowing	BaseMutationNarrowing

Defined in: packages/angular-query-experimental/src/types.ts:328

The isSuccess/isError/isPending/isIdle methods on a mutation result. Each is both a Signal (its current boolean value is read reactively without calling it) and a type-guard function you can call — if (mutation.isSuccess()) — so that mutation.data narrows away undefined inside the branch.

Type Parameters

TData

TData = unknown

The type your mutation function resolves to.

TError

TError = DefaultError

The type of errors your mutation function may throw.

TVariables

TVariables = unknown

The type of the variable passed to mutate/mutateAsync.

TOnMutateResult

TOnMutateResult = unknown

The type returned by onMutate, passed to onSuccess/onError/onSettled as their onMutateResult parameter — useful for optimistic-update rollback data.

Properties

isError

isError: SignalFunction<(this) => this is CreateMutationResult<TData, TError, TVariables, TOnMutateResult, Override<MutationObserverErrorResult<TData, TError, TVariables, TOnMutateResult>, { mutate: CreateMutateFunction<TData, TError, TVariables, TOnMutateResult> }> & { mutateAsync: CreateMutateAsyncFunction<TData, TError, TVariables, TOnMutateResult> }>>;

Defined in: packages/angular-query-experimental/src/types.ts:351

---

isIdle

isIdle: SignalFunction<(this) => this is CreateMutationResult<TData, TError, TVariables, TOnMutateResult, Override<MutationObserverIdleResult<TData, TError, TVariables, TOnMutateResult>, { mutate: CreateMutateFunction<TData, TError, TVariables, TOnMutateResult> }> & { mutateAsync: CreateMutateAsyncFunction<TData, TError, TVariables, TOnMutateResult> }>>;

Defined in: packages/angular-query-experimental/src/types.ts:385

---

isPending

isPending: SignalFunction<(this) => this is CreateMutationResult<TData, TError, TVariables, TOnMutateResult, Override<MutationObserverLoadingResult<TData, TError, TVariables, TOnMutateResult>, { mutate: CreateMutateFunction<TData, TError, TVariables, TOnMutateResult> }> & { mutateAsync: CreateMutateAsyncFunction<TData, TError, TVariables, TOnMutateResult> }>>;

Defined in: packages/angular-query-experimental/src/types.ts:368

---

isSuccess

isSuccess: SignalFunction<(this) => this is CreateMutationResult<TData, TError, TVariables, TOnMutateResult, Override<MutationObserverSuccessResult<TData, TError, TVariables, TOnMutateResult>, { mutate: CreateMutateFunction<TData, TError, TVariables, TOnMutateResult> }> & { mutateAsync: CreateMutateAsyncFunction<TData, TError, TVariables, TOnMutateResult> }>>;

Defined in: packages/angular-query-experimental/src/types.ts:334