Method createResult

packages/query-core/src/queryObserver.ts:433–643

(
    query: Query<TQueryFnData, TError, TQueryData, TQueryKey>,
    options: QueryObserverOptions<
      TQueryFnData,
      TError,
      TData,
      TQueryData,
      TQueryKey
    >,
  )

  }

  protected createResult(
    query: Query<TQueryFnData, TError, TQueryData, TQueryKey>,
    options: QueryObserverOptions<
      TQueryFnData,
      TError,
      TData,
      TQueryData,
      TQueryKey
    >,
  ): QueryObserverResult<TData, TError> {
    const prevQuery = this.#currentQuery
    const prevOptions = this.options
    const prevResult = this.#currentResult as
      | QueryObserverResult<TData, TError>
      | undefined
    const prevResultState = this.#currentResultState
    const prevResultOptions = this.#currentResultOptions
    const queryChange = query !== prevQuery
    const queryInitialState = queryChange
      ? query.state
      : this.#currentQueryInitialState

    const { state } = query
    let newState = { ...state }
    let isPlaceholderData = false
    let data: TData | undefined

    // Optimistically set result in fetching state if needed
    if (options._optimisticResults) {
      const mounted = this.hasListeners()

      const fetchOnMount = !mounted && shouldFetchOnMount(query, options)

      const fetchOptionally =
        mounted && shouldFetchOptionally(query, prevQuery, options, prevOptions)

      if (fetchOnMount || fetchOptionally) {
        newState = {
          ...newState,
          ...fetchState(state.data, query.options),
        }
      }
      if (options._optimisticResults === 'isRestoring') {
        newState.fetchStatus = 'idle'
      }
    }

    let { error, errorUpdatedAt, status } = newState

    // Per default, use query data
    data = newState.data as unknown as TData
    let skipSelect = false

    // use placeholderData if needed
    if (
      options.placeholderData !== undefined &&
      data === undefined &&
      status === 'pending'