fix(module: form): validation would be reset when model changes (#1035)

* fix(module:form): form.reset() will make new editContext

fixes 947

* fix(module:form): validation is reset when model changes

fixes 851
fixes 982
fixes 991

* feat(module:form): validation reset method

components/form/Form.razor.cs

@@ -1,6 +1,5 @@
 using System;
 using System.Collections.Generic;
-using System.Linq;
 using System.Threading.Tasks;
 using AntDesign.Forms;
 using AntDesign.Internal;
@@ -61,7 +60,18 @@ public partial class Form<TModel> : AntDomComponentBase, IForm
         public string Name { get; set; }
 
         [Parameter]
-        public TModel Model { get; set; }
+        public TModel Model
+        {
+            get { return _model; }
+            set
+            {
+                if (!(_model?.Equals(value) ?? false))
+                {
+                    _model = value;
+                    _editContext = new EditContext(Model);
+                }
+            }
+        }
 
         [Parameter]
         public bool Loading { get; set; }
@@ -95,6 +105,7 @@ public partial class Form<TModel> : AntDomComponentBase, IForm
         private EditContext _editContext;
         private IList<IFormItem> _formItems = new List<IFormItem>();
         private IList<IControlValueAccessor> _controls = new List<IControlValueAccessor>();
+        private TModel _model;
 
         ColLayoutParam IForm.WrapperCol => WrapperCol;
 
@@ -153,6 +164,7 @@ private async Task OnInvalidSubmit(EditContext editContext)
         public void Reset()
         {
             _controls.ForEach(item => item.Reset());
+            _editContext = new EditContext(Model);
         }
 
         void IForm.AddFormItem(IFormItem formItem)
@@ -188,5 +200,10 @@ public bool Validate()
         {
             return _editContext.Validate();
         }
+
+        public void ValidationReset()
+        {
+            _editContext = new EditContext(Model);
+        }
     }
 }