🔀 Merge branch 'rel/0.2.0' into stable

Fixes https://codeberg.org/danjones000/gin-error-handler/issues/1

CHANGELOG.md

@@ -0,0 +1,24 @@
+# Changelog
+
+## [0.2.0] - 2024-02-07
+
+### Fixed
+
+- [Using HandlerWithError as Middleware allows response to be sent](https://codeberg.org/danjones000/gin-error-handler/issues/1)
+- Error response still sent if other response is already sent, resulting in duplicate body
+
+## [0.1.0] - 2024-01-22
+
+🎉 Initial release
+
+### Added
+
+- HandlerWithError
+  + HandlerWithErrorWrapper
+- ErrorMiddleware
+  + Option
+    * Transformer
+      - WithTransformer
+      - WithDefaultTransformer
+    * LoggerFunc
+      - WithLogger

README.md

@@ -1,3 +1,87 @@
 # Gin Error Handler
 
 A Gin middleware and wrapper functions to make handling errors easier.
+
+## Installation
+
+Use the module in the usual way: `codeberg.org/danjones000/gin-error-handler`.
+
+## Usage
+
+```go
+package main
+
+import (
+    "net/http"
+    handler "codeberg.org/danjones000/gin-error-handler"
+    rErrors "codeberg.org/danjones000/responsable-errors"
+    "github.com/go-playground/validator/v10"
+    "github.com/gin-gonic/gin"
+)
+
+var _ rErrors.ResponsableError = new(vError)
+
+type vError struct {
+    validator.ValidationErrors
+}
+
+func (ve *vError) Msg() string {
+    return "Validation Error"
+}
+
+func (ve *vError) Status() int {
+    return http.StatusBadRequest
+}
+
+func (ve *vError) JSON() any {
+    errs := make([]map[string]string, len(ve))
+    for i, fe := range ve {
+        errs[i] = map[string]string{"field":fe.Field(),"error":fe.Error()}
+    }
+    return map[string][]map[string]string{"errors":errs}
+}
+
+func (ve *vError) MarshalJSON() ([]byte, error) {
+	return json.Marshal(e.JSON())
+}
+
+func (ve *vError) Unwrap() error {
+	return ve.ValidationErrors
+}
+
+func main() {
+    r := gin.New()
+    r.Use(handler.ErrorMiddleware(
+        handler.WithTransformer(func (err error) rErrors.ResponsableError {
+            var ve validator.ValidationErrors
+            if !errors.As(err, &ve) {
+                return nil
+            }
+            return &vError{ve}
+        }),
+        handler.WithDefaultTransformer(),
+        handler.WithLogger(ctx context.Context, err rErrors.ResponsableError) {
+            log.Print(err)
+        })
+
+    r.GET("/user", handler.HandlerWithErrorWrapper(func (c *gin.Context) error {
+        var qu struct {
+            id int `binding:"required"`
+        }{}
+        if err := c.ShouldBindQuery(&qu); err != nil {
+            return err
+        }
+        user, err := user.Get(qu.id)
+        if err != nil {
+            return err
+        }
+        if user == nil {
+            return rErrors.NewNotFound("User not found")
+        }
+
+        c.JSON(200, user)
+    }))
+}
+```
+
+In our example, if `ShouldBindQuery` fails validation, we'll return a nicely formatted error with each validation error, due to our custom transformer. If no user is found, we'll return a 404, with an error message. And any errors are logged to stdout.

go.mod

@@ -3,7 +3,7 @@ module codeberg.org/danjones000/gin-error-handler
 go 1.21.5
 
 require (
-	codeberg.org/danjones000/responsable-errors v0.2.0
+	codeberg.org/danjones000/responsable-errors v0.2.1
 	github.com/gin-gonic/gin v1.9.1
 	github.com/stretchr/testify v1.8.4
 )

go.sum

@@ -1,7 +1,5 @@
-codeberg.org/danjones000/responsable-errors v0.1.1 h1:WTWo0egPNsp+kEKRK8R+yc/bfdEDUbwEjMnqgA7IklA=
-codeberg.org/danjones000/responsable-errors v0.1.1/go.mod h1:susEj39A/bflyej4tRirtuVKkmfUdhR2Skljwd/1ndI=
-codeberg.org/danjones000/responsable-errors v0.2.0 h1:WUTBSaKQzkXHDYraHt3mxB4QHqVk78sKR/VeteXM1OY=
-codeberg.org/danjones000/responsable-errors v0.2.0/go.mod h1:susEj39A/bflyej4tRirtuVKkmfUdhR2Skljwd/1ndI=
+codeberg.org/danjones000/responsable-errors v0.2.1 h1:Ur6t+QZWaAfBgjQWBqSCgS3sTySdkKQD/FQefeRrm90=
+codeberg.org/danjones000/responsable-errors v0.2.1/go.mod h1:susEj39A/bflyej4tRirtuVKkmfUdhR2Skljwd/1ndI=
 github.com/bytedance/sonic v1.5.0/go.mod h1:ED5hyg4y6t3/9Ku1R6dU/4KyJ48DZ4jPhfY1O2AihPM=
 github.com/bytedance/sonic v1.9.1 h1:6iJ6NqdoxCDr6mbY8h18oSO+cShGSMRGCEo7F2h0x8s=
 github.com/bytedance/sonic v1.9.1/go.mod h1:i736AoUSYt75HyZLoJW9ERYxcy6eaN6h4BZXU064P/U=

handler.go

@@ -25,6 +25,8 @@ func HandlerWithErrorWrapper(h HandlerWithError) gin.HandlerFunc {
 	return func(c *gin.Context) {
 		err := h(c)
 		if err != nil {
+			// We shouldn't process more handlers if there was an error
+			c.Abort()
 			c.Error(err)
 		}
 	}

int_test.go

@@ -0,0 +1,47 @@
+package handler
+
+import (
+	"net/http"
+	"net/http/httptest"
+	"testing"
+
+	errors "codeberg.org/danjones000/responsable-errors"
+	"github.com/gin-gonic/gin"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestErrorMiddleware(t *testing.T) {
+	gin.SetMode(gin.TestMode)
+	w := httptest.NewRecorder()
+	_, r := gin.CreateTestContext(w)
+	r.Use(ErrorMiddleware())
+	r.Use(HandlerWithErrorWrapper(func(c *gin.Context) error {
+		return errors.Errorf(400, "Oops")
+	}))
+	r.GET("/", func(c *gin.Context) {
+		c.JSON(200, gin.H{"Hello": "World"})
+	})
+	req, _ := http.NewRequest("GET", "/", nil)
+	r.ServeHTTP(w, req)
+
+	assert.Equal(t, 400, w.Code)
+	assert.Equal(t, `{"error":"Oops"}`, w.Body.String())
+}
+
+func TestErrorNoResponseIfAlreadyWritten(t *testing.T) {
+	gin.SetMode(gin.TestMode)
+	w := httptest.NewRecorder()
+	_, r := gin.CreateTestContext(w)
+	r.Use(ErrorMiddleware())
+
+	r.GET("/", HandlerWithErrorWrapper(func(c *gin.Context) error {
+		c.JSON(200, gin.H{"Hello": "World"})
+		return errors.Errorf(400, "Oops")
+	}))
+	req, _ := http.NewRequest("GET", "/", nil)
+	r.ServeHTTP(w, req)
+
+	assert.Equal(t, 200, w.Code)
+	assert.Equal(t, `{"Hello":"World"}`, w.Body.String())
+
+}

middleware.go

@@ -55,7 +55,8 @@ func ErrorMiddleware(opts ...Option) gin.HandlerFunc {
 
 		c.Set("rendered_error", re)
 
-		// @todo check a response hasn't already been sent
-		c.JSON(re.Status(), re)
+		if !c.Writer.Written() {
+			c.JSON(re.Status(), re)
+		}
 	}
 }