feat: Add OnError to Client

Support the error hook, which will be executed if any error will be returned

client.go

@@ -18,11 +18,12 @@ import (
 	"strings"
 	"time"
 
+	utls "github.com/refraction-networking/utls"
+	"golang.org/x/net/publicsuffix"
+
 	"github.com/imroc/req/v3/http2"
 	"github.com/imroc/req/v3/internal/header"
 	"github.com/imroc/req/v3/internal/util"
-	utls "github.com/refraction-networking/utls"
-	"golang.org/x/net/publicsuffix"
 )
 
 // DefaultClient returns the global default Client.
@@ -70,8 +71,11 @@ type Client struct {
 	roundTripWrappers       []RoundTripWrapper
 	responseBodyTransformer func(rawBody []byte, req *Request, resp *Response) (transformedBody []byte, err error)
 	resultStateCheckFunc    func(resp *Response) ResultState
+	onError                 ErrorHook
 }
 
+type ErrorHook func(client *Client, req *Request, resp *Response, err error)
+
 // R create a new request.
 func (c *Client) R() *Request {
 	return &Request{
@@ -981,6 +985,13 @@ func (c *Client) SetProxy(proxy func(*http.Request) (*urlpkg.URL, error)) *Clien
 	return c
 }
 
+// OnError set the error hook which will be executed if any error returned,
+// even if the occurs before request is sent (e.g. invalid URL).
+func (c *Client) OnError(hook ErrorHook) *Client {
+	c.onError = hook
+	return c
+}
+
 // OnBeforeRequest add a request middleware which hooks before request sent.
 func (c *Client) OnBeforeRequest(m RequestMiddleware) *Client {
 	c.udBeforeRequest = append(c.udBeforeRequest, m)

request.go

@@ -15,6 +15,7 @@ import (
 	"time"
 
 	"github.com/hashicorp/go-multierror"
+
 	"github.com/imroc/req/v3/internal/dump"
 	"github.com/imroc/req/v3/internal/header"
 	"github.com/imroc/req/v3/internal/util"
@@ -285,9 +286,11 @@ func (r *Request) SetFile(paramName, filePath string) *Request {
 	})
 }
 
-var errMissingParamName = errors.New("missing param name in multipart file upload")
-var errMissingFileName = errors.New("missing filename in multipart file upload")
-var errMissingFileContent = errors.New("missing file content in multipart file upload")
+var (
+	errMissingParamName   = errors.New("missing param name in multipart file upload")
+	errMissingFileName    = errors.New("missing filename in multipart file upload")
+	errMissingFileContent = errors.New("missing file content in multipart file upload")
+)
 
 // SetFileUpload set the fully custimized multipart file upload options.
 func (r *Request) SetFileUpload(uploads ...FileUpload) *Request {
@@ -695,8 +698,6 @@ func (r *Request) do() (resp *Response, err error) {
 		resp.result = nil
 		resp.error = nil
 	}
-
-	return
 }
 
 // Send fires http request with specified method and url, returns the
@@ -705,6 +706,9 @@ func (r *Request) Send(method, url string) (*Response, error) {
 	r.Method = method
 	r.RawURL = url
 	resp := r.Do()
+	if resp.Err != nil && r.client.onError != nil {
+		r.client.onError(r.client, r, resp, resp.Err)
+	}
 	return resp, resp.Err
 }