Fix #67: Add WriteJSON helper to httpserver package

application/healthcheck.go

@@ -2,9 +2,9 @@ package application
 
 import (
 	"context"
-	"encoding/json"
 	"net/http"
 
+	"github.com/platforma-dev/platforma/httpserver"
 	"github.com/platforma-dev/platforma/log"
 )
 
@@ -25,11 +25,7 @@ func NewHealthCheckHandler(app healther) *HealthCheckHandler {
 func (h *HealthCheckHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	health := h.app.Health(r.Context())
 
-	w.Header().Set("Content-Type", "application/json")
-	w.WriteHeader(http.StatusOK)
-
-	err := json.NewEncoder(w).Encode(health)
-	if err != nil {
-		log.ErrorContext(r.Context(), "failed to encode response to json", "error", err)
+	if err := httpserver.WriteJSON(w, http.StatusOK, health); err != nil {
+		log.ErrorContext(r.Context(), "failed to write health response", "error", err)
 	}
 }

auth/handler_delete.go

@@ -2,10 +2,10 @@ package auth
 
 import (
 	"context"
-	"encoding/json"
 	"errors"
 	"net/http"
 
+	"github.com/platforma-dev/platforma/httpserver"
 	"github.com/platforma-dev/platforma/log"
 )
 
@@ -41,8 +41,7 @@ func (h *DeleteHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	w.WriteHeader(http.StatusOK)
-	if err := json.NewEncoder(w).Encode("User deleted successfully"); err != nil {
-		log.ErrorContext(ctx, "failed to decode response to json", "error", err)
+	if err := httpserver.WriteJSON(w, http.StatusOK, "User deleted successfully"); err != nil {
+		log.ErrorContext(ctx, "failed to write delete response", "error", err)
 	}
 }

auth/handler_get.go

@@ -1,9 +1,9 @@
 package auth
 
 import (
-	"encoding/json"
 	"net/http"
 
+	"github.com/platforma-dev/platforma/httpserver"
 	"github.com/platforma-dev/platforma/log"
 )
 
@@ -42,16 +42,13 @@ func (h *GetHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	w.Header().Set("Content-Type", "application/json")
-
-	var resp = struct {
+	resp := struct {
 		Username string `json:"username"`
 	}{
 		Username: user.Username,
 	}
 
-	err = json.NewEncoder(w).Encode(resp)
-	if err != nil {
-		log.ErrorContext(ctx, "failed to decode response to json", "error", err)
+	if err := httpserver.WriteJSON(w, http.StatusOK, resp); err != nil {
+		log.ErrorContext(ctx, "failed to write user response", "error", err)
 	}
 }

httpserver/response.go

@@ -0,0 +1,21 @@
+package httpserver
+
+import (
+	"encoding/json"
+	"fmt"
+	"net/http"
+)
+
+// WriteJSON writes a JSON response with the specified status code.
+// It sets the Content-Type header to application/json and encodes the data as JSON.
+// Returns an error if encoding fails.
+func WriteJSON(w http.ResponseWriter, statusCode int, data any) error {
+	w.Header().Set("Content-Type", "application/json")
+	w.WriteHeader(statusCode)
+
+	if err := json.NewEncoder(w).Encode(data); err != nil {
+		return fmt.Errorf("failed to encode response to json: %w", err)
+	}
+
+	return nil
+}

httpserver/response_test.go

@@ -0,0 +1,94 @@
+package httpserver_test
+
+import (
+	"encoding/json"
+	"io"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+
+	"github.com/platforma-dev/platforma/httpserver"
+)
+
+func TestWriteJSON(t *testing.T) {
+	t.Parallel()
+
+	t.Run("writes json response with status code", func(t *testing.T) {
+		t.Parallel()
+
+		data := map[string]string{"message": "hello"}
+
+		w := httptest.NewRecorder()
+
+		err := httpserver.WriteJSON(w, http.StatusCreated, data)
+		if err != nil {
+			t.Fatalf("unexpected error: %v", err)
+		}
+
+		resp := w.Result()
+		if resp.StatusCode != http.StatusCreated {
+			t.Fatalf("expected status code %d, got %d", http.StatusCreated, resp.StatusCode)
+		}
+
+		contentType := resp.Header.Get("Content-Type")
+		if contentType != "application/json" {
+			t.Fatalf("expected Content-Type 'application/json', got %s", contentType)
+		}
+
+		body, _ := io.ReadAll(resp.Body)
+		var result map[string]string
+		if err := json.Unmarshal(body, &result); err != nil {
+			t.Fatalf("failed to unmarshal response body: %v", err)
+		}
+
+		if result["message"] != "hello" {
+			t.Fatalf("expected message 'hello', got %s", result["message"])
+		}
+	})
+
+	t.Run("writes struct as json", func(t *testing.T) {
+		t.Parallel()
+
+		type TestStruct struct {
+			ID   int    `json:"id"`
+			Name string `json:"name"`
+		}
+
+		data := TestStruct{ID: 1, Name: "test"}
+
+		w := httptest.NewRecorder()
+
+		err := httpserver.WriteJSON(w, http.StatusOK, data)
+		if err != nil {
+			t.Fatalf("unexpected error: %v", err)
+		}
+
+		resp := w.Result()
+		body, _ := io.ReadAll(resp.Body)
+		var result TestStruct
+		if err := json.Unmarshal(body, &result); err != nil {
+			t.Fatalf("failed to unmarshal response body: %v", err)
+		}
+
+		if result.ID != 1 || result.Name != "test" {
+			t.Fatalf("unexpected result: %+v", result)
+		}
+	})
+
+	t.Run("returns error on unencodable data", func(t *testing.T) {
+		t.Parallel()
+
+		w := httptest.NewRecorder()
+
+		unencodable := make(chan int)
+
+		err := httpserver.WriteJSON(w, http.StatusOK, unencodable)
+		if err == nil {
+			t.Fatal("expected error for unencodable data")
+		}
+
+		if err.Error() == "" {
+			t.Fatal("expected non-empty error message")
+		}
+	})
+}