Support validator interface in JSONHandler

.github/dependabot.yml

@@ -0,0 +1,10 @@
+version: 2
+updates:
+  - package-ecosystem: "gomod"
+    directory: "/"
+    schedule:
+      interval: "weekly"
+  - package-ecosystem: "github-actions"
+    directory: "/"
+    schedule:
+      interval: "weekly"

.github/workflows/ci.yml

@@ -10,7 +10,7 @@ on:
 
 concurrency:
   group: ${{ github.workflow }}-${{ github.ref_name }}
-  cancel-in-progress: true
+  cancel-in-progress: ${{ github.ref_name != 'main' }}
 
 jobs:
   test:
@@ -36,6 +36,7 @@ jobs:
   lint:
     name: Lint
     runs-on: ubuntu-latest
+    if: ${{ github.triggering_actor != 'dependabot[bot]' }}
 
     steps:
       - name: Checkout
@@ -48,6 +49,6 @@ jobs:
           check-latest: true
 
       - name: Lint
-        uses: golangci/golangci-lint-action@v4
+        uses: golangci/golangci-lint-action@v6
         with:
           version: latest

README.md

@@ -1,12 +1,12 @@
 # httph
 
 [![GoDoc](https://pkg.go.dev/badge/maragu.dev/httph)](https://pkg.go.dev/maragu.dev/httph)
-[![Go](https://github.com/maragudk/httph/actions/workflows/ci.yml/badge.svg)](https://github.com/maragudk/httph/actions/workflows/ci.yml)
+[![CI](https://github.com/maragudk/httph/actions/workflows/ci.yml/badge.svg)](https://github.com/maragudk/httph/actions/workflows/ci.yml)
 
 HTTP helpers and middleware. H is for helpful!
 
 ```shell
 go get maragu.dev/httph
 ```
 
-Made in 🇩🇰 by [maragu](https://www.maragu.dk/), maker of [online Go courses](https://www.golang.dk/).
+Made with ✨sparkles✨ by [maragu](https://www.maragu.dev/).

go.mod

@@ -2,7 +2,6 @@ module maragu.dev/httph
 
 go 1.19
 
-require (
-	github.com/maragudk/is v0.1.0
-	github.com/mitchellh/mapstructure v1.5.0
-)
+require github.com/mitchellh/mapstructure v1.5.0
+
+require maragu.dev/is v0.2.0

go.sum

@@ -1,4 +1,4 @@
-github.com/maragudk/is v0.1.0 h1:obq9anZNmOYcaNbeT0LMyjIexdNeYTw/TLAPD/BnZHA=
-github.com/maragudk/is v0.1.0/go.mod h1:W/r6+TpnISu+a88OLXQy5JQGCOhXQXXLD2e5b4xMn5c=
 github.com/mitchellh/mapstructure v1.5.0 h1:jeMsZIYE/09sWLaz43PL7Gy6RuMjD2eJVyuac5Z2hdY=
 github.com/mitchellh/mapstructure v1.5.0/go.mod h1:bFUtVrKA4DC2yAKiSyO/QUcy7e+RRV2QTWOzhPopBRo=
+maragu.dev/is v0.2.0 h1:poeuVEA5GG3vrDpGmzo2KjWtIMZmqUyvGnOB0/pemig=
+maragu.dev/is v0.2.0/go.mod h1:bviaM5S0fBshCw7wuumFGTju/izopZ/Yvq4g7Klc7y8=

httph.go

@@ -78,9 +78,11 @@ func JSONHandler[Req any, Res any](h func(http.ResponseWriter, *http.Request, Re
 		}
 
 		// Try reading a request body, skip if there is none
+		var foundRequestBody bool
 		br := bufio.NewReader(r.Body)
 		if _, err := br.Peek(1); err == nil {
 			dec := json.NewDecoder(br)
+			foundRequestBody = true
 
 			if err := dec.Decode(&req); err != nil {
 				w.WriteHeader(http.StatusBadRequest)
@@ -91,6 +93,16 @@ func JSONHandler[Req any, Res any](h func(http.ResponseWriter, *http.Request, Re
 			}
 		}
 
+		if req, ok := any(req).(validator); ok && foundRequestBody {
+			if err := req.Validate(); err != nil {
+				w.WriteHeader(http.StatusBadRequest)
+				writeResponse(w, errorResponse{
+					Error: fmt.Errorf("invalid request body: %w", err).Error(),
+				})
+				return
+			}
+		}
+
 		res, err := h(w, r, req)
 		if err != nil {
 			code := http.StatusInternalServerError

httph_test.go

@@ -11,9 +11,8 @@ import (
 	"strings"
 	"testing"
 
-	"github.com/maragudk/is"
-
 	"maragu.dev/httph"
+	"maragu.dev/is"
 )
 
 type validatedFormReq struct{}
@@ -156,6 +155,17 @@ func (t tinyJSONReq) MaxSizeBytes() int64 {
 	return 1
 }
 
+type validatedJSONReq struct {
+	Name string
+}
+
+func (v validatedJSONReq) Validate() error {
+	if v.Name == "" {
+		return errors.New("name cannot be empty")
+	}
+	return nil
+}
+
 func TestJSONHandler(t *testing.T) {
 	t.Run("encodes response body to JSON", func(t *testing.T) {
 		type jsonRes struct {
@@ -283,6 +293,21 @@ func TestJSONHandler(t *testing.T) {
 		is.Equal(t, http.StatusBadRequest, res.Result().StatusCode)
 		is.Equal(t, `{"Error":"error decoding request body as JSON: http: request body too large"}`, readBody(t, res))
 	})
+
+	t.Run("returns bad request if request body fails validation", func(t *testing.T) {
+		h := httph.JSONHandler(func(w http.ResponseWriter, r *http.Request, req validatedJSONReq) (any, error) {
+			return nil, nil
+		})
+
+		req := httptest.NewRequest(http.MethodPost, "/", strings.NewReader(`{"Name":""}`))
+		req.Header.Set("Content-Type", "application/json")
+		res := httptest.NewRecorder()
+
+		h.ServeHTTP(res, req)
+
+		is.Equal(t, http.StatusBadRequest, res.Result().StatusCode)
+		is.Equal(t, `{"Error":"invalid request body: name cannot be empty"}`, readBody(t, res))
+	})
 }
 
 func ExampleJSONHandler() {