kb(Form): keep form items order (#2095)

Author: xristianstefanov

knowledge-base/form-keep-fields-order.md

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+---
+title: Keep Form Items Rendering Order after Show/Hide
+description: How to keep the form item rendering order when changing the form item visibility.
+type: how-to
+page_title: Keep Form Items Rendering Order after Show/Hide
+slug: form-kb-keep-fields-order
+position: 
+tags: 
+ticketid: 1647539
+res_type: kb
+---
+
+## Environment
+<table>
+	<tbody>
+		<tr>
+			<td>Product</td>
+			<td>Form for Blazor</td>
+		</tr>
+	</tbody>
+</table>
+
+## Description
+
+This knowledge base article answers the following questions:
+
+* How do I keep the rendering order of Form items?
+* Is it possible to toggle the visibility of a Form item and keep its rendering order instead of showing it as last?
+
+## Solution
+
+The `<FormItems>` tag doesn't render Form items directly. This tag is used only to register `<FormItem>` instances. The Form considers conditional field items, whose visibility may change, as the last items to be processed.
+
+To preserve the rendering place of each form item, you need to use the `TelerikFormItemRenderer`.
+
+````CSHTML
+<TelerikForm Model="@model">
+    <FormItems>
+
+        <FormItem Field="@nameof(FormModel.Field1)">
+            <Template>
+                <label>Field1</label>
+                <TelerikRadioGroup Data="@Items" TextField="@nameof(RadioButtonItem.TextField)" ValueField="@nameof(RadioButtonItem.ValueField)" @bind-Value="@model.Field1"
+                                   Layout="RadioGroupLayout.Horizontal">
+                </TelerikRadioGroup>
+            </Template>
+        </FormItem>
+
+        <FormItem Field="@nameof(FormModel.Field2)">
+            <Template>
+                <label>Field2</label>
+                <TelerikNumericTextBox @bind-Value="@model.Field2"></TelerikNumericTextBox>
+            </Template>
+        </FormItem>
+
+        <FormItem Field="@nameof(FormModel.Field3)">
+            <Template>
+                <label>Field3</label>
+                <TelerikNumericTextBox @bind-Value="@model.Field3"></TelerikNumericTextBox>
+            </Template>
+        </FormItem>
+
+    </FormItems>
+
+    <FormItemsTemplate Context="formContext">
+        @{
+            var formItems = formContext.Items.Cast<IFormItem>();
+        }
+        <TelerikFormItemRenderer Item="@formItems.First(x => x.Field == nameof(FormModel.Field1))" />
+        @if (model.Field1 == 2)
+        {
+            <TelerikFormItemRenderer Item="@formItems.First(x => x.Field == nameof(FormModel.Field2))" />
+        }
+        <TelerikFormItemRenderer Item="@formItems.First(x => x.Field == nameof(FormModel.Field3))" />
+    </FormItemsTemplate>
+</TelerikForm>
+
+@code {
+    private FormModel model { get; set; } = new FormModel();
+
+    private List<RadioButtonItem> Items = new List<RadioButtonItem>()
+    {
+        new RadioButtonItem { ValueField = 1, TextField = "Item 1" },
+        new RadioButtonItem { ValueField = 2, TextField = "Item 2" },
+        new RadioButtonItem { ValueField = 3, TextField = "Item 3" },
+    };
+
+    public class FormModel
+    {
+        public int Field1 { get; set; }
+        public int Field2 { get; set; }
+        public int Field3 { get; set; }
+    }
+
+    public class RadioButtonItem
+    {
+        public string TextField { get; set; }
+        public int ValueField { get; set; }
+    }
+}
+````
+
+## See Also
+
+* [Form Template for All Items]({%slug form-formitems-formitemstemplate%})