minor changes to MVC, see HISTORY.md#Next for more

HISTORY.md

@@ -23,6 +23,12 @@ Developers are not forced to upgrade if they don't really need it. Upgrade whene
 
 Changes apply to `main` branch.
 
+- Add optional `Singleton() bool` method to controllers to mark them as singleton, will panic with a specific error if a controller expects dynamic dependencies. This behavior is idendical to the app-driven `app.EnsureStaticBindings()`.
+
+- Non-zero fields of a controller that are marked as ignored, with `ignore:"true"` field tag, they are not included in the dependencies at all now.
+
+- Re-add error log on context rich write (e.g. JSON) failures when the application is running under debug mode (with `app.Logger().SetLevel("debug")`) and there is no a registered context error handler at place.
+
 - `master` branch finally renamed to `main`. Don't worry GitHub will still navigate any `master` request to `main` automatically. Examples, Documentation and other Pages are refactored too.
 
 # Sat, 12 Aug 2023 | v12.2.4

context/context.go

@@ -4213,6 +4213,9 @@ func (ctx *Context) handleContextError(err error) {
 	if errHandler := ctx.app.GetContextErrorHandler(); errHandler != nil {
 		errHandler.HandleContextError(ctx, err)
 	} else {
+		if ctx.IsDebug() {
+			ctx.app.Logger().Error(err)
+		}
 		ctx.StatusCode(http.StatusInternalServerError)
 	}
 
@@ -4258,8 +4261,8 @@ func (ctx *Context) JSON(v interface{}, opts ...JSON) (err error) {
 	}
 
 	if err = ctx.writeJSON(v, options); err != nil {
-		// if no options are given or OmitErrorHandler is true
-		// then do call the error handler (which may lead to a cycle).
+		// if no options are given or OmitErrorHandler is false
+		// then call the error handler (which may lead to a cycle if the error handler fails to write JSON too).
 		if !options.OmitErrorHandler {
 			ctx.handleContextError(err)
 		}

hero/reflect.go

@@ -201,6 +201,9 @@ func lookupFields(elem reflect.Value, skipUnexported bool, onlyZeros bool, paren
 func lookupNonZeroFieldValues(elem reflect.Value) (nonZeroFields []reflect.StructField) {
 	fields, _ := lookupFields(elem, true, false, nil)
 	for _, f := range fields {
+		if structFieldIgnored(f) {
+			continue // re-check here for ignored struct fields so we don't include them on dependencies. Non-zeroes fields can be static, even if they are functions.
+		}
 		if fieldVal := elem.FieldByIndex(f.Index); goodVal(fieldVal) && !isZero(fieldVal) {
 			/* && f.Type.Kind() == reflect.Ptr &&*/
 			nonZeroFields = append(nonZeroFields, f)

hero/struct.go

@@ -43,6 +43,18 @@ type Struct struct {
 	Singleton bool
 }
 
+type singletonStruct interface {
+	Singleton() bool
+}
+
+func isMarkedAsSingleton(structPtr any) bool {
+	if sing, ok := structPtr.(singletonStruct); ok && sing.Singleton() {
+		return true
+	}
+
+	return false
+}
+
 func makeStruct(structPtr interface{}, c *Container, partyParamsCount int) *Struct {
 	v := valueOf(structPtr)
 	typ := v.Type()
@@ -50,8 +62,19 @@ func makeStruct(structPtr interface{}, c *Container, partyParamsCount int) *Stru
 		panic("binder: struct: should be a pointer to a struct value")
 	}
 
+	isSingleton := isMarkedAsSingleton(structPtr)
+
+	disablePayloadAutoBinding := c.DisablePayloadAutoBinding
+	enableStructDependents := c.EnableStructDependents
+	disableStructDynamicBindings := c.DisableStructDynamicBindings
+	if isSingleton {
+		disablePayloadAutoBinding = true
+		enableStructDependents = false
+		disableStructDynamicBindings = true
+	}
+
 	// get struct's fields bindings.
-	bindings := getBindingsForStruct(v, c.Dependencies, c.MarkExportedFieldsAsRequired, c.DisablePayloadAutoBinding, c.EnableStructDependents, c.DependencyMatcher, partyParamsCount, c.Sorter)
+	bindings := getBindingsForStruct(v, c.Dependencies, c.MarkExportedFieldsAsRequired, disablePayloadAutoBinding, enableStructDependents, c.DependencyMatcher, partyParamsCount, c.Sorter)
 
 	// length bindings of 0, means that it has no fields or all mapped deps are static.
 	// If static then Struct.Acquire will return the same "value" instance, otherwise it will create a new one.
@@ -73,7 +96,7 @@ func makeStruct(structPtr interface{}, c *Container, partyParamsCount int) *Stru
 
 			elem.FieldByIndex(b.Input.StructFieldIndex).Set(input)
 		} else if !b.Dependency.Static {
-			if c.DisableStructDynamicBindings {
+			if disableStructDynamicBindings {
 				panic(fmt.Sprintf("binder: DisableStructDynamicBindings setting is set to true: dynamic binding found: %s", b.String()))
 			}
 
@@ -81,6 +104,10 @@ func makeStruct(structPtr interface{}, c *Container, partyParamsCount int) *Stru
 		}
 	}
 
+	if isSingleton && !singleton {
+		panic(fmt.Sprintf("binder: Singleton setting is set to true but struct has dynamic bindings: %s", typ))
+	}
+
 	s := &Struct{
 		ptrValue:    v,
 		ptrType:     typ,