feat: add request decode func (#1)

Add the go request decode function that supports json unmarshalling, string query params and string headers

.gitignore

@@ -0,0 +1 @@
+coverage.out

Makefile

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+test:
+	go test -cover ./... 
+	golangci-lint run ./...
+
+test-coverage:
+	go test -coverpkg ./... -coverprofile coverage.out ./... && go tool cover -html=coverage.out

README.md

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+#GO Request
+
+Go Request is a package built to decode `*http.Request` data into a custom struct. Using struct tags we are about to pull HTTP request data from the request's:
+- Body
+- Header
+- Query
+- Path
+
+Example using the following request:
+```bash 
+curl --location --request POST 'www.example.com/user/adam?game=go' \
+--header 'X-DELAY: 60' \
+--header 'Content-Type: application/json' \
+--data-raw '{
+    "state": "idle"
+}'
+```
+
+
+```go
+import ("github.com/jesse0michael/go-request")
+
+type MyRequest struct {
+    Name  string `path:"name"`
+    Game  string `query:"game"`
+    State string `json:"state"`
+    Delay int64  `header:"X-DELAY"`
+}
+
+
+func(w http.ResponseWriter, r *http.Request) {
+    var req MyRequest
+
+    err := request.Decode(r, &req)
+    if err != nil {
+        w.WriteHeader(400)
+    }
+
+    fmt.Println(req)
+}
+```
+
+```
+
+```

go.mod

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+module github.com/jesse0michael/go-request
+
+go 1.17
+
+require github.com/gorilla/mux v1.8.0

go.sum

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+github.com/gorilla/mux v1.8.0 h1:i40aqfkR1h2SlN9hojwV5ZA91wcXFOvkdNIeFDP5koI=
+github.com/gorilla/mux v1.8.0/go.mod h1:DVbg23sWSpFRCP0SfiEN6jmj59UnW/n46BH5rLB71So=

request.go

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+package request
+
+import (
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+	"reflect"
+)
+
+func Decode(r *http.Request, data interface{}) error {
+	err := decodeBody(r, data)
+	if err != nil {
+		return err
+	}
+
+	err = decodeRequest(r, data)
+	if err != nil {
+		return err
+	}
+
+	return nil
+}
+
+func decodeRequest(r *http.Request, data interface{}) error {
+	typ := reflect.TypeOf(data)
+	if typ == nil {
+		return fmt.Errorf("invalid decode type: nil")
+	}
+	if typ.Kind() == reflect.Ptr {
+		typ = typ.Elem()
+	}
+	if typ.Kind() != reflect.Struct {
+		return fmt.Errorf("invalid decode type: %v", typ.Kind())
+	}
+
+	val := reflect.ValueOf(data).Elem()
+	for i := 0; i < typ.NumField(); i++ {
+		err := decodeField(r, typ.Field(i), val.Field(i))
+		if err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+func decodeField(r *http.Request, typ reflect.StructField, val reflect.Value) error {
+	query := r.URL.Query()
+	queryTag := typ.Tag.Get("query")
+	if queryTag != "" {
+		if query.Has(queryTag) {
+			v := query.Get(queryTag)
+			val.Set(reflect.ValueOf(v))
+		}
+	}
+
+	headerTag := typ.Tag.Get("header")
+	if headerTag != "" {
+		if r.Header.Get(headerTag) != "" {
+			v := r.Header.Get(headerTag)
+			val.Set(reflect.ValueOf(v))
+		}
+	}
+
+	return nil
+}
+
+func decodeBody(r *http.Request, data interface{}) error {
+	b, err := io.ReadAll(r.Body)
+	if err != nil {
+		return err
+	}
+	defer r.Body.Close()
+
+	switch r.Header.Get("Content-Type") {
+	case "application/json":
+		err := json.Unmarshal(b, &data)
+		if err != nil {
+			return err
+		}
+	}
+
+	return nil
+}

request_test.go

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+package request
+
+import (
+	"fmt"
+	"net/http"
+	"net/http/httptest"
+	"strings"
+
+	"github.com/gorilla/mux"
+)
+
+type MyRequest struct {
+	Name  string `path:"name"`
+	Game  string `query:"game"`
+	State string `json:"state"`
+	Delay string `header:"X-DELAY"`
+}
+
+func ExampleDecode() {
+	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		var req MyRequest
+		err := Decode(r, &req)
+		if err != nil {
+			w.WriteHeader(http.StatusBadRequest)
+		}
+
+		fmt.Printf("%+v\n", req)
+	}))
+	defer ts.Close()
+
+	body := `{"state":"idle"}`
+	req, _ := http.NewRequest(http.MethodPost, ts.URL+"?game=go", strings.NewReader(body))
+	req.Header.Set("Content-Type", "application/json")
+	req.Header.Set("X-DELAY", "60")
+	resp, err := http.DefaultClient.Do(req)
+	if err != nil {
+		fmt.Println("request failed")
+	}
+	if resp.StatusCode == http.StatusBadRequest {
+		fmt.Println("decode failed")
+	}
+	// Output:
+	// {Name: Game:go State:idle Delay:60}
+}
+
+func ExampleDecode_mux() {
+	r := mux.NewRouter()
+	r.Handle("/test/{name}", http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		var req MyRequest
+		err := Decode(r, &req)
+		if err != nil {
+			w.WriteHeader(http.StatusBadRequest)
+		}
+
+		fmt.Printf("%+v\n", req)
+	}))
+
+	body := `{"state":"idle"}`
+	req, _ := http.NewRequest(http.MethodPost, "http://www.example.com/test/user?game=go", strings.NewReader(body))
+	req.Header.Set("Content-Type", "application/json")
+	req.Header.Set("X-DELAY", "60")
+	rec := httptest.NewRecorder()
+	r.ServeHTTP(rec, req)
+	if rec.Code == http.StatusBadRequest {
+		fmt.Println("decode failed")
+	}
+	// Output:
+	// {Name: Game:go State:idle Delay:60}
+}