feat(useFetch): introduce updateDataOnError option

packages/core/useFetch/index.md

@@ -113,19 +113,22 @@ const { data } = useFetch(url, {
 })
 ```
 
-The `onFetchError` option can intercept the response data and error before it is updated.
+The `onFetchError` option can intercept the response data and error before it is updated when `updateDataOnError` is set to `true`.
+
 ```ts
 const { data } = useFetch(url, {
+  updateDataOnError: true,
   onFetchError(ctx) {
     // ctx.data can be null when 5xx response
     if (ctx.data === null)
       ctx.data = { title: 'Hunter x Hunter' } // Modifies the response data
 
     ctx.error = new Error('Custom Error') // Modifies the error
-
     return ctx
   },
 })
+
+console.log(data.value) // { title: 'Hunter x Hunter' }
 ```
 
 ### Setting the request method and return type

packages/core/useFetch/index.test.ts

@@ -542,6 +542,7 @@ describe.skipIf(isBelowNode18)('useFetch', () => {
     const { data, error, statusCode } = useFetch('https://example.com?status=400&json', {
       onFetchError(ctx) {
         ctx.error = 'Internal Server Error'
+        ctx.data = 'Internal Server Error'
         return ctx
       },
     }).json()
@@ -553,6 +554,23 @@ describe.skipIf(isBelowNode18)('useFetch', () => {
     })
   })
 
+  it('should return data in onFetchError when updateDataOnError is true', async () => {
+    const { data, error, statusCode } = useFetch('https://example.com?status=400&json', {
+      updateDataOnError: true,
+      onFetchError(ctx) {
+        ctx.error = 'Internal Server Error'
+        ctx.data = 'Internal Server Error'
+        return ctx
+      },
+    }).json()
+
+    await retry(() => {
+      expect(statusCode.value).toEqual(400)
+      expect(error.value).toEqual('Internal Server Error')
+      expect(data.value).toEqual('Internal Server Error')
+    })
+  })
+
   it('should run the onFetchError function when network error', async () => {
     const { data, error, statusCode } = useFetch('https://example.com?status=500&text=Internal%20Server%20Error', {
       onFetchError(ctx) {

packages/core/useFetch/index.ts

@@ -163,6 +163,13 @@ export interface UseFetchOptions {
    */
   timeout?: number
 
+  /**
+   * Allow update the `data` ref when fetch error whenever provided, or mutated in the `onFetchError` callback
+   *
+   * @default false
+   */
+  updateDataOnError?: boolean
+
   /**
    * Will run immediately before the fetch request is dispatched
    */
@@ -211,7 +218,7 @@ export interface CreateFetchOptions {
  * to include the new options
  */
 function isFetchOptions(obj: object): obj is UseFetchOptions {
-  return obj && containsProp(obj, 'immediate', 'refetch', 'initialData', 'timeout', 'beforeFetch', 'afterFetch', 'onFetchError', 'fetch')
+  return obj && containsProp(obj, 'immediate', 'refetch', 'initialData', 'timeout', 'beforeFetch', 'afterFetch', 'onFetchError', 'fetch', 'updateDataOnError')
 }
 
 // A URL is considered absolute if it begins with "<scheme>://" or "//" (protocol-relative URL).
@@ -314,8 +321,20 @@ export function useFetch<T>(url: MaybeRefOrGetter<string>, ...args: any[]): UseF
   const supportsAbort = typeof AbortController === 'function'
 
   let fetchOptions: RequestInit = {}
-  let options: UseFetchOptions = { immediate: true, refetch: false, timeout: 0 }
-  interface InternalConfig { method: HttpMethod; type: DataType; payload: unknown; payloadType?: string }
+  let options: UseFetchOptions = {
+    immediate: true,
+    refetch: false,
+    timeout: 0,
+    updateDataOnError: false,
+  }
+
+  interface InternalConfig {
+    method: HttpMethod
+    type: DataType
+    payload: unknown
+    payloadType?: string
+  }
+
   const config: InternalConfig = {
     method: 'GET',
     type: 'text' as DataType,
@@ -454,8 +473,12 @@ export function useFetch<T>(url: MaybeRefOrGetter<string>, ...args: any[]): UseF
             throw new Error(fetchResponse.statusText)
           }
 
-          if (options.afterFetch)
-            ({ data: responseData } = await options.afterFetch({ data: responseData, response: fetchResponse }))
+          if (options.afterFetch) {
+            ({ data: responseData } = await options.afterFetch({
+              data: responseData,
+              response: fetchResponse,
+            }))
+          }
           data.value = responseData
 
           responseEvent.trigger(fetchResponse)
@@ -464,9 +487,17 @@ export function useFetch<T>(url: MaybeRefOrGetter<string>, ...args: any[]): UseF
         .catch(async (fetchError) => {
           let errorData = fetchError.message || fetchError.name
 
-          if (options.onFetchError)
-            ({ error: errorData } = await options.onFetchError({ data: responseData, error: fetchError, response: response.value }))
+          if (options.onFetchError) {
+            ({ error: errorData, data: responseData } = await options.onFetchError({
+              data: responseData,
+              error: fetchError,
+              response: response.value,
+            }))
+          }
+
           error.value = errorData
+          if (options.updateDataOnError)
+            data.value = responseData
 
           errorEvent.trigger(fetchError)
           if (throwOnFailed)