Added new kb article grid-kb-create-reusable-columns

Author: KB Bot

knowledge-base/grid-kb-create-reusable-columns.md

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+---
+title: Reusable Grid Columns with Templates
+description: Learn how to encapsulate GridColumn, including templates, into a reusable component for Telerik UI for Blazor Grid.
+type: how-to
+page_title: How to Make Reusable GridColumn Components with Templates in Blazor
+slug: grid-kb-create-reusable-columns
+tags: grid, blazor, gridcolumn, reusable component, templates, editor template
+res_type: kb
+ticketid: 1671641
+---
+
+## Description
+This knowledge base article answers the following questions:
+- How can I create a reusable `GridColumn` component in Blazor?
+- What is the best way to encapsulate `GridColumn` templates in a reusable component?
+
+## Environment
+<table>
+    <tbody>
+	    <tr>
+	    	<td>Product</td>
+	    	<td>Grid for Blazor</td>
+	    </tr>
+    </tbody>
+</table>
+
+## Solution
+To create a reusable `GridColumn` component with templates, follow these steps:
+
+1. Define a custom column component that accepts parameters for the field, title, whether it uses templates, and the currently edited item.
+
+2. Within the custom component, conditionally render a `GridColumn` with or without templates based on the provided parameters.
+
+````RAZOR Index.razor
+<TelerikGrid Data="@MyData" EditMode="@GridEditMode.Incell" Pageable="true" OnUpdate="@UpdateHandler">
+    <GridColumns>
+        <CustomColumn TItem="@Employee" Field="@(nameof(Employee.ID))"></CustomColumn>
+        <CustomColumn TItem="@Employee" Field="@(nameof(Employee.Name))"></CustomColumn>
+        <CustomColumn TItem="@Employee" EditedEmployee="@CurrentlyEditedEmployee" IsTemplate="@true" Field=@nameof(Employee.RoleId) Title="Position"></CustomColumn>
+    </GridColumns>
+</TelerikGrid>
+
+@code {
+    private List<Employee> MyData { get; set; }
+    private Employee CurrentlyEditedEmployee { get; set; }
+
+    private async Task UpdateHandler(GridCommandEventArgs args)
+    {
+        Employee item = (Employee)args.Item;
+
+        await MyService.Update(item);
+
+        await GetGridData();
+    }
+
+    private async Task GetGridData()
+    {
+        MyData = await MyService.Read();
+    }
+
+    protected override async Task OnInitializedAsync()
+    {
+        await GetGridData();
+    }
+
+    public static class MyService
+    {
+        private static List<Employee> _data { get; set; } = new List<Employee>();
+
+        public static async Task<List<Employee>> Read()
+        {
+            if (_data.Count < 1)
+            {
+                for (int i = 0; i < 50; i++)
+                {
+                    _data.Add(new Employee()
+                    {
+                        ID = i,
+                        Name = "name " + i,
+                        RoleId = i % 4
+                    });
+                }
+            }
+
+            return await Task.FromResult(_data);
+        }
+
+        public static async Task Update(Employee itemToUpdate)
+        {
+            var index = _data.FindIndex(i => i.ID == itemToUpdate.ID);
+            if (index != -1)
+            {
+                _data[index] = itemToUpdate;
+            }
+        }
+    }
+}
+````
+
+````RAZOR CustomColumn.razor
+@typeparam TItem
+
+@if (IsTemplate)
+{
+    <GridColumn Field="@Field" Title="@Title">
+        <Template>
+            @{
+                int roleId = (context as Employee).RoleId;
+                Role matchingPos = Roles.FirstOrDefault(r => r.RoleId == roleId);
+                string textToRender = matchingPos != null ? matchingPos.RoleName : "Unknown";
+                <text>@textToRender</text>
+            }
+        </Template>
+        <EditorTemplate>
+            @{
+                EditedEmployee = context as Employee;
+                <TelerikDropDownList Data="@Roles"
+                                     @bind-Value="@EditedEmployee.RoleId"
+                                     TextField="@nameof(Role.RoleName)"
+                                     ValueField="@nameof(Role.RoleId)"
+                                     DefaultText="Select Role">
+                    <DropDownListSettings>
+                        <DropDownListPopupSettings Height="auto" />
+                    </DropDownListSettings>
+                </TelerikDropDownList>
+            }
+        </EditorTemplate>
+    </GridColumn>
+}
+else
+{
+    <GridColumn Field="@Field"></GridColumn>
+}
+
+@code {
+    [Parameter]
+    public string Field { get; set; }
+    
+    [Parameter]
+    public string Title { get; set; }
+
+    [Parameter]
+    public bool IsTemplate { get; set; }
+
+    [Parameter]
+    public Employee EditedEmployee { get; set; }
+
+    private List<Role> Roles { get; set; } = new List<Role>
+    {
+        new Role { RoleId = 1, RoleName = "Manager" },
+        new Role { RoleId = 2, RoleName = "Employee" },
+        new Role { RoleId = 3, RoleName = "Contractor" },
+    };
+}
+````
+
+````C# Employee.cs
+public class Employee
+    {
+        public int ID { get; set; }
+        public string Name { get; set; }
+        public int RoleId { get; set; }
+    }
+````
+````C# Role.cs
+public class Role
+    {
+        public int RoleId { get; set; }
+        public string RoleName { get; set; }
+    }
+````
+
+## See Also
+
+- [Grid Columns](https://docs.telerik.com/blazor-ui/components/grid/columns/bound)
+- [Grid Templates](https://docs.telerik.com/blazor-ui/components/grid/templates)