Merge pull request #5 from DmitryBochkarev/GetOk

GetOk(r, key) (value, ok)

context.go

@@ -37,6 +37,17 @@ func Get(r *http.Request, key interface{}) interface{} {
 	return nil
 }
 
+// GetOk returns stored value and presence state like multi-value return of map access.
+func GetOk(r *http.Request, key interface{}) (interface{}, bool) {
+	mutex.Lock()
+	defer mutex.Unlock()
+	if _, ok := data[r]; ok {
+		value, ok := data[r][key]
+		return value, ok
+	}
+	return nil, false
+}
+
 // Delete removes a value stored for a given key in a given request.
 func Delete(r *http.Request, key interface{}) {
 	mutex.Lock()

context_test.go

@@ -37,14 +37,28 @@ func TestContext(t *testing.T) {
 	assertEqual(Get(r, key2), "2")
 	assertEqual(len(data[r]), 2)
 
+	//GetOk
+	value, ok := GetOk(r, key1)
+	assertEqual(value, "1")
+	assertEqual(ok, true)
+
+	value, ok = GetOk(r, "not exists")
+	assertEqual(value, nil)
+	assertEqual(ok, false)
+
+	Set(r, "nil value", nil)
+	value, ok = GetOk(r, "nil value")
+	assertEqual(value, nil)
+	assertEqual(ok, true)
+
 	// Delete()
 	Delete(r, key1)
 	assertEqual(Get(r, key1), nil)
-	assertEqual(len(data[r]), 1)
+	assertEqual(len(data[r]), 2)
 
 	Delete(r, key2)
 	assertEqual(Get(r, key2), nil)
-	assertEqual(len(data[r]), 0)
+	assertEqual(len(data[r]), 1)
 
 	// Clear()
 	Clear(r)

doc.go

@@ -37,8 +37,10 @@ The application can later access the variable using the same key you provided:
 
 	func MyHandler(w http.ResponseWriter, r *http.Request) {
 		// val is "bar".
-		val = context.Get(r, foo.MyKey)
+		val := context.Get(r, foo.MyKey)
 
+		// returns ("bar", true)
+		val, ok := context.GetOk(r, foo.MyKey)
 		// ...
 	}