add iris.IsErrEmptyJSON helper. See HISTORY.md

HISTORY.md

@@ -28,6 +28,25 @@ The codebase for Dependency Injection, Internationalization and localization and
 
 ## Fixes and Improvements
 
+- New `iris.IsErrEmptyJSON(err) bool` which reports whether the given "err" is caused by a
+`Context.ReadJSON` call when the request body didn't start with { (or it was totally empty). 
+
+Example Code:
+
+```go
+func handler(ctx iris.Context) {
+    var opts SearchOptions
+    if err := ctx.ReadJSON(&opts); err != nil && !iris.IsErrEmptyJSON(err) {
+        ctx.StopWithJSON(iris.StatusBadRequest, iris.Map{"message": "unable to parse body"})
+        return
+    }
+
+    // [...continue with default values of "opts" struct if the client didn't provide some]
+}
+```
+
+That means that the client can optionally set a JSON body.
+	
 - New `APIContainer.EnableStrictMode(bool)` to disable automatic payload binding and panic on missing dependencies for exported struct'sfields or function's input parameters on MVC controller or hero function or PartyConfigurator.
 
 - New `Party.PartyConfigure(relativePath string, partyReg ...PartyConfigurator) Party` helper, registers a children Party like `Party` and `PartyFunc` but instead it accepts a structure value which may contain one or more of the dependencies registered by `RegisterDependency` or `ConfigureContainer().RegisterDependency` methods and fills the unset/zero exported struct's fields respectfully (useful when the api's dependencies amount are too much to pass on a function).

_examples/dependency-injection/basic/middleware/main.go

@@ -47,6 +47,12 @@ func newApp() *iris.Application {
 	// or 202 status code and empty body
 	// or a 409 status code and "my_error" body.
 	app.ConfigureContainer(func(api *iris.APIContainer) {
+		// TODO: fix that test as well.
+		// api.Self.SetExecutionRules(iris.ExecutionRules{
+		// 	Begin: iris.ExecutionOptions{
+		// 		Force: true,
+		// 	},
+		// })
 		api.Use(middleware)
 		api.Post("/{id:int}", handler)
 	})

aliases.go

@@ -496,6 +496,10 @@ var (
 	// A shortcut for the `context#CookieEncoding`.
 	CookieEncoding = context.CookieEncoding
 
+	// IsErrEmptyJSON reports whether the given "err" is caused by a
+	// Context.ReadJSON call when the request body
+	// didn't start with { or it was totally empty.
+	IsErrEmptyJSON = context.IsErrEmptyJSON
 	// IsErrPath can be used at `context#ReadForm` and `context#ReadQuery`.
 	// It reports whether the incoming error is type of `schema.ErrPath`,
 	// which can be ignored when server allows unknown post values to be sent by the client.

context/context.go

@@ -2311,13 +2311,13 @@ func (ctx *Context) decodeBody(outPtr interface{}, decoder internalBodyDecoder)
 	// but this is up to the user's custom Decode implementation*
 	//
 	// See 'BodyDecoder' for more.
-	if decoder, isDecoder := outPtr.(BodyDecoder); isDecoder {
+	if structDecoder, isDecoder := outPtr.(BodyDecoder); isDecoder {
 		rawData, err := ctx.GetBody()
 		if err != nil {
 			return err
 		}
 
-		return decoder.Decode(rawData)
+		return structDecoder.Decode(rawData)
 	}
 
 	err := decoder.Decode(outPtr)
@@ -2465,6 +2465,23 @@ func (ctx *Context) ReadYAML(outPtr interface{}) error {
 }
 
 var (
+	// IsErrEmptyJSON reports whether the given "err" is caused by a
+	// Context.ReadJSON call when the request body
+	// didn't start with { or it was totally empty.
+	IsErrEmptyJSON = func(err error) bool {
+		if err == nil {
+			return false
+		}
+
+		if v, ok := err.(*json.SyntaxError); ok {
+			// standard go json encoder error.
+			return v.Offset == 0 && v.Error() == "unexpected end of JSON input"
+		}
+
+		// when optimization is enabled, the jsoniter will report the following error:
+		return strings.Contains(err.Error(), "readObjectStart: expect {")
+	}
+
 	// IsErrPath can be used at `context#ReadForm` and `context#ReadQuery`.
 	// It reports whether the incoming error
 	// can be ignored when server allows unknown post values to be sent by the client.