body is empty error

glossd · Dec 9, 2024 · 7852776 · 7852776
1 parent b498387
commit 7852776
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Showing 5 changed files with 51 additions and 26 deletions.
diff --git a/README.md b/README.md
@@ -301,7 +301,7 @@ http.HandleFunc("/pets", fetch.ToHandlerFunc(func(in Pet) (*Pet, error) {
 }))
 http.ListenAndServe(":8080", nil)
 ```
-If you don't need request or response body, you can use `any` to fit the function signature. However, `fetch.Empty` will completely ignore the request or response body.
+If you have empty request or response body or you want to ignore them, use  `fetch.Empty`:
 ```go
 http.HandleFunc("/default-pet", fetch.ToHandlerFunc(func(_ fetch.Empty) (Pet, error) {
     return Pet{Name: "Teddy"}, nil

diff --git a/fetch.go b/fetch.go
@@ -193,7 +193,7 @@ func Do[T any](url string, config ...Config) (T, error) {
 		err = parseBodyInto(body, resInstance)
 		if err != nil {
 			var t T
-			return t, httpErr("parsing JSON error: ", err, res, body)
+			return t, httpErr("parse response body: ", err, res, body)
 		}
 
 		valueOf := reflect.Indirect(reflect.ValueOf(&t))
@@ -206,7 +206,7 @@ func Do[T any](url string, config ...Config) (T, error) {
 	err = parseBodyInto(body, &t)
 	if err != nil {
 		var t T
-		return t, httpErr("parsing JSON error: ", err, res, body)
+		return t, httpErr("parse response body: ", err, res, body)
 	}
 	return t, nil
 }
@@ -229,6 +229,9 @@ func parseBodyInto(body []byte, v any) error {
 		rve.SetBytes(body)
 		return nil
 	}
+	if len(body) == 0 {
+		return fmt.Errorf("body is empty")
+	}
 	err := UnmarshalInto(string(body), v)
 	if err != nil {
 		return err

diff --git a/respond_test.go b/respond_test.go
@@ -10,14 +10,14 @@ import (
 type mockWriter struct {
 	status int
 	header http.Header
-	body   []byte
+	body   string
 }
 
 func newMockWriter() *mockWriter {
 	return &mockWriter{
 		status: 0,
 		header: http.Header{},
-		body:   nil,
+		body:   "",
 	}
 }
 
@@ -30,7 +30,7 @@ func (mw *mockWriter) Header() http.Header {
 }
 
 func (mw *mockWriter) Write(b []byte) (int, error) {
-	mw.body = b
+	mw.body = string(b)
 	return 0, nil
 }
 
@@ -52,7 +52,7 @@ func TestRespond_Struct(t *testing.T) {
 	assert(t, err, nil)
 	assert(t, mw.status, 200)
 	assert(t, mw.Header().Get("Content-Type"), "application/json")
-	assert(t, strings.TrimSpace(string(mw.body)), `{"id":"my-id"}`)
+	assert(t, strings.TrimSpace(mw.body), `{"id":"my-id"}`)
 }
 
 func TestRespond_InvalidJSON(t *testing.T) {
@@ -64,7 +64,7 @@ func TestRespond_InvalidJSON(t *testing.T) {
 	assertNotNil(t, err)
 	assert(t, mw.status, 500)
 	assert(t, mw.Header().Get("Content-Type"), "application/json")
-	assert(t, strings.HasPrefix(string(mw.body), `{"error":`), true)
+	assert(t, strings.HasPrefix(mw.body, `{"error":`), true)
 }
 
 func TestRespond_InvalidStatus(t *testing.T) {
@@ -73,7 +73,7 @@ func TestRespond_InvalidStatus(t *testing.T) {
 	assertNotNil(t, err)
 	assert(t, mw.status, 500)
 	assert(t, mw.Header().Get("Content-Type"), "application/json")
-	assert(t, strings.HasPrefix(string(mw.body), `{"error":`), true)
+	assert(t, strings.HasPrefix(mw.body, `{"error":`), true)
 }
 
 func TestSetRespondErrorFormat(t *testing.T) {
@@ -85,7 +85,7 @@ func TestSetRespondErrorFormat(t *testing.T) {
 	mw := newMockWriter()
 	Respond(mw, "hello", RespondConfig{Status: 51})
 	assert(t, mw.header.Get("Content-Type"), "text/plain")
-	assert(t, string(mw.body), "RespondConfig.Status is invalid")
+	assert(t, mw.body, "RespondConfig.Status is invalid")
 }
 
 func TestSetRespondErrorFormat_InvalidFormats(t *testing.T) {
@@ -125,8 +125,8 @@ func TestRespondResponse(t *testing.T) {
 	mw := newMockWriter()
 	err := Respond(mw, Response[Pet]{Status: 201, Body: Pet{Name: "Lola"}})
 	assert(t, err, nil)
-	if mw.status != 201 || string(mw.body) != `{"name":"Lola"}` {
-		t.Errorf("wrong writer: %+v, %s", mw, string(mw.body))
+	if mw.status != 201 || mw.body != `{"name":"Lola"}` {
+		t.Errorf("wrong writer: %+v, %s", mw, mw.body)
 	}
 }
 
@@ -136,7 +136,7 @@ func TestRespondError(t *testing.T) {
 	assert(t, err, nil)
 	assert(t, mw.status, 400)
 	assert(t, mw.Header().Get("Content-Type"), "application/json")
-	assert(t, string(mw.body), `{"error":"wrong"}`)
+	assert(t, mw.body, `{"error":"wrong"}`)
 }
 
 func assert[T comparable](t *testing.T, got, want T) {

diff --git a/to_handler.go b/to_handler.go
@@ -71,33 +71,23 @@ func ToHandlerFunc[In any, Out any](apply ApplyFunc[In, Out]) http.HandlerFunc {
 			}
 			resInstance := reflect.New(resType.Type).Interface()
 			if !isEmptyType(resInstance) {
-				reqBody, err := io.ReadAll(r.Body)
+				err := readAndParseBody(r, resInstance)
 				if err != nil {
 					cfg.respondError(w, err)
 					return
 				}
-				err = parseBodyInto(reqBody, resInstance)
-				if err != nil {
-					cfg.respondError(w, fmt.Errorf("failed to parse request body: %s", err))
-					return
-				}
 			}
 			valueOf := reflect.Indirect(reflect.ValueOf(&in))
 			valueOf.FieldByName("PathValues").Set(reflect.ValueOf(extractPathValues(r)))
 			valueOf.FieldByName("Context").Set(reflect.ValueOf(r.Context()))
 			valueOf.FieldByName("Headers").Set(reflect.ValueOf(uniqueHeaders(r.Header)))
 			valueOf.FieldByName("Body").Set(reflect.ValueOf(resInstance).Elem())
 		} else if !isEmptyType(in) {
-			reqBody, err := io.ReadAll(r.Body)
+			err := readAndParseBody(r, &in)
 			if err != nil {
 				cfg.respondError(w, err)
 				return
 			}
-			err = parseBodyInto(reqBody, &in)
-			if err != nil {
-				cfg.respondError(w, fmt.Errorf("failed to parse request body: %s", err))
-				return
-			}
 		}
 
 		out, err := apply(in)
@@ -119,6 +109,18 @@ func ToHandlerFunc[In any, Out any](apply ApplyFunc[In, Out]) http.HandlerFunc {
 	}
 }
 
+func readAndParseBody(r *http.Request, in any) error {
+	reqBody, err := io.ReadAll(r.Body)
+	if err != nil {
+		return err
+	}
+	err = parseBodyInto(reqBody, in)
+	if err != nil {
+		return fmt.Errorf("parse request body: %s", err)
+	}
+	return nil
+}
+
 func extractPathValues(r *http.Request) map[string]string {
 	if !isGo23AndAbove() || r == nil {
 		return map[string]string{}

diff --git a/to_handler_test.go b/to_handler_test.go
@@ -29,7 +29,7 @@ func TestToHandlerFunc_EmptyOut(t *testing.T) {
 	assert(t, err, nil)
 	f(mw, r)
 	assert(t, mw.status, 200)
-	assert(t, string(mw.body), ``)
+	assert(t, mw.body, ``)
 }
 
 // This test should fail to compile on go1.21 and successfully run on go1.22.
@@ -87,6 +87,26 @@ func TestToHandlerFunc_Header(t *testing.T) {
 	assert(t, mw.status, 200)
 }
 
+func TestToHandlerFunc_ParseErrors(t *testing.T) {
+	t.Run("Empty Request Body, Struct with fields", func(t *testing.T) {
+		type Pet struct {
+			Name string
+		}
+		f := ToHandlerFunc(func(in Request[Pet]) (Empty, error) {
+			return Empty{}, nil
+		})
+		mw := newMockWriter()
+		mux := http.NewServeMux()
+		mux.HandleFunc("/pets", f)
+		r, err := http.NewRequest("POST", "/pets", bytes.NewBuffer([]byte(``)))
+		assert(t, err, nil)
+		mux.ServeHTTP(mw, r)
+		if mw.status != 400 || mw.body != `{"error":"parse request body: body is empty"}` {
+			t.Errorf("Wrong writer: %+v", mw)
+		}
+	})
+}
+
 func TestToHandlerFunc_Context(t *testing.T) {
 	f := ToHandlerFunc(func(in Request[Empty]) (Empty, error) {
 		assert(t, in.Context.Err(), nil)