Fix for #1775 and #1760 (#1781)

fix two issues on required field validation issues in Dynamic Form Control

Author: wuxiaojun514

src/controls/dynamicForm/DynamicForm.tsx

@@ -354,7 +354,7 @@ export class DynamicForm extends React.Component<
 
         // When a field is required and has no value
         if (field.required) {
-          if (field.newValue === null) {
+          if (field.newValue === undefined && field.value===undefined) {
             if (
               field.defaultValue === null ||
               field.defaultValue === "" ||

src/controls/dynamicForm/dynamicField/DynamicField.tsx

@@ -625,7 +625,15 @@ export class DynamicField extends React.Component<IDynamicFieldProps, IDynamicFi
     const {
       changedValue
     } = this.state;
-    return (changedValue === undefined || changedValue === '' || changedValue === null || this.isEmptyArray(changedValue)) && this.props.required ? strings.DynamicFormRequiredErrorMessage : null;
+    const {value,newValue,required}=this.props;
+    if(newValue===undefined){
+      return required && (changedValue === undefined || changedValue === '' || changedValue === null || this.isEmptyArray(changedValue)) 
+      && (value === undefined || value === '' || value === null || this.isEmptyArray(value))? strings.DynamicFormRequiredErrorMessage : null;
+    }
+    else{
+      return required && (changedValue === undefined || changedValue === '' || changedValue === null || this.isEmptyArray(changedValue)) ? strings.DynamicFormRequiredErrorMessage : null;
+    }
+   
   }
 
   private getNumberErrorText = (): string => {
@@ -637,10 +645,17 @@ export class DynamicField extends React.Component<IDynamicFieldProps, IDynamicFi
       fieldType,
       maximumValue,
       minimumValue,
-      showAsPercentage
+      showAsPercentage,
+      value,
+      newValue,
+      required
     } = this.props;
 
-    if ((changedValue === undefined || changedValue === '' || changedValue === null || this.isEmptyArray(changedValue)) && this.props.required) {
+    if (required && newValue!==undefined && (changedValue === undefined || changedValue === '' || changedValue === null || this.isEmptyArray(changedValue)) ) {
+      return strings.DynamicFormRequiredErrorMessage;
+    }
+
+    if (required && newValue===undefined &&  (value === undefined || value === '' || value === null || this.isEmptyArray(value)) && (changedValue === undefined || changedValue === '' || changedValue === null || this.isEmptyArray(changedValue)) ) {
       return strings.DynamicFormRequiredErrorMessage;
     }