feat(handler): implement duplicate read closer for request body

handler.go

@@ -30,6 +30,31 @@ func ChainHandlers(handlers ...ResponseHandler) ResponseHandler {
 	}
 }
 
+// KeepRespBodyHandlers Combine multiple ResponseHandler and ensure that each processor has access to the original response body
+func KeepRespBodyHandlers(handlers ...ResponseHandler) ResponseHandler {
+	return func(r *http.Response) error {
+		for _, h := range handlers {
+			if h == nil {
+				continue
+			}
+
+			var dup io.ReadCloser
+			r.Body, dup = dupReadCloser(r.Body)
+			if err := h(r); err != nil {
+				return err
+			}
+			r.Body = dup
+		}
+		return nil
+	}
+}
+
+func dupReadCloser(reader io.ReadCloser) (io.ReadCloser, io.ReadCloser) {
+	var buf bytes.Buffer
+	tee := io.TeeReader(reader, &buf)
+	return io.NopCloser(tee), io.NopCloser(&buf)
+}
+
 func consumeBody(res *http.Response) (err error) {
 	const maxDiscardSize = 640 * 1 << 10
 	if _, err = io.CopyN(io.Discard, res.Body, maxDiscardSize); err == io.EOF {

handler_test.go

@@ -1,8 +1,10 @@
 package requests_test
 
 import (
+	"bytes"
 	"context"
 	"fmt"
+	"io"
 	"net/http"
 	"os"
 	"path/filepath"
@@ -32,3 +34,37 @@ func BenchmarkBuilder_ToFile(b *testing.B) {
 		be.NilErr(b, err)
 	}
 }
+
+// TestKeepRespBodyHandlers tests the KeepRespBodyHandlers function.
+func TestKeepRespBodyHandlers(t *testing.T) {
+	type Common struct {
+		ID int `json:"id"`
+	}
+
+	type Book struct {
+		Common
+		Name string `json:"name"`
+	}
+
+	var (
+		book   Book
+		common Common
+		str    string
+	)
+
+	handler := requests.KeepRespBodyHandlers(
+		requests.ToJSON(&common),
+		requests.ToJSON(&book),
+		requests.ToString(&str),
+	)
+
+	err := handler(&http.Response{
+		Body: io.NopCloser(bytes.NewReader([]byte(`{"id":1, "name":"孙子兵法"}`))),
+	})
+
+	be.NilErr(t, err)
+	be.Equal(t, 1, common.ID)
+	be.Equal(t, 1, book.ID)
+	be.Equal(t, "孙子兵法", book.Name)
+	be.Equal(t, `{"id":1, "name":"孙子兵法"}`, str)
+}