snapshot of https://github.com/TanStack/query.git (main, 2026-09-16; blobs > 131072B omitted)

docs/framework/angular/reference/interfaces/BaseMutationNarrowing.md

@@ -0,0 +1,77 @@
+---
+id: BaseMutationNarrowing
+title: BaseMutationNarrowing
+---
+
+Defined in: [packages/angular-query-experimental/src/types.ts:328](https://github.com/TanStack/query/blob/main/packages/angular-query-experimental/src/types.ts#L328)
+
+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`](../type-aliases/DefaultError.md)
+
+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
+
+```ts
+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](https://github.com/TanStack/query/blob/main/packages/angular-query-experimental/src/types.ts#L351)
+
+***
+
+### isIdle
+
+```ts
+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](https://github.com/TanStack/query/blob/main/packages/angular-query-experimental/src/types.ts#L385)
+
+***
+
+### isPending
+
+```ts
+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](https://github.com/TanStack/query/blob/main/packages/angular-query-experimental/src/types.ts#L368)
+
+***
+
+### isSuccess
+
+```ts
+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](https://github.com/TanStack/query/blob/main/packages/angular-query-experimental/src/types.ts#L334)