|
| 1 | +--- |
| 2 | +title: Validation |
| 3 | +page_title: Grid Validation |
| 4 | +description: Built-in validation in the Grid and how to customize the validation behavior. |
| 5 | +slug: grid-editing-validation |
| 6 | +tags: telerik,blazor,grid,validation,editing |
| 7 | +published: True |
| 8 | +position: 40 |
| 9 | +--- |
| 10 | + |
| 11 | +# Grid Validation |
| 12 | + |
| 13 | +The Telerik UI for Blazor Grid supports built-in validation that is enabled by default. The Grid passes an `EditContext` as a cascading value to the editable cells. If any validation messages are present, the Grid will render them as [Validation Tooltips]({%slug validation-tools-tooltip%}) on hover of the specific editor. |
| 14 | + |
| 15 | +#### In this Article: |
| 16 | + |
| 17 | +* [Disable the validation](#disable-the-validation) |
| 18 | +* [Use a custom validator](#use-custom-validator) |
| 19 | + |
| 20 | +## Disable Validation |
| 21 | + |
| 22 | +To disable the built-in validation, add a `<GridValidationSettings>` tag to the `<GridSettings>` and set the `Enabled` parameter to `false`. |
| 23 | + |
| 24 | +````CSHTML |
| 25 | +@* Disable the built-in validation in the Grid *@ |
| 26 | +
|
| 27 | +@using System.ComponentModel.DataAnnotations @* for the validation attributes *@ |
| 28 | +
|
| 29 | +<TelerikGrid Data=@MyData EditMode="@GridEditMode.Inline" Pageable="true" Height="500px" |
| 30 | + OnUpdate="@UpdateHandler" OnEdit="@EditHandler" OnDelete="@DeleteHandler" OnCreate="@CreateHandler" OnCancel="@CancelHandler"> |
| 31 | + <GridSettings> |
| 32 | + <GridValidationSettings Enabled="false"> |
| 33 | + </GridValidationSettings> |
| 34 | + </GridSettings> |
| 35 | + <GridToolBar> |
| 36 | + <GridCommandButton Command="Add" Icon="add">Add Employee</GridCommandButton> |
| 37 | + </GridToolBar> |
| 38 | + <GridColumns> |
| 39 | + <GridColumn Field=@nameof(SampleData.ID) Title="ID" Editable="false" /> |
| 40 | + <GridColumn Field=@nameof(SampleData.Name) Title="Name" /> |
| 41 | + <GridCommandColumn> |
| 42 | + <GridCommandButton Command="Save" Icon="save" ShowInEdit="true">Update</GridCommandButton> |
| 43 | + <GridCommandButton Command="Edit" Icon="edit">Edit</GridCommandButton> |
| 44 | + <GridCommandButton Command="Delete" Icon="delete">Delete</GridCommandButton> |
| 45 | + <GridCommandButton Command="Cancel" Icon="cancel" ShowInEdit="true">Cancel</GridCommandButton> |
| 46 | + </GridCommandColumn> |
| 47 | + </GridColumns> |
| 48 | +</TelerikGrid> |
| 49 | +
|
| 50 | +@code { |
| 51 | + void EditHandler(GridCommandEventArgs args) |
| 52 | + { |
| 53 | + SampleData item = (SampleData)args.Item; |
| 54 | +
|
| 55 | + // prevent opening for edit based on condition |
| 56 | + if (item.ID < 3) |
| 57 | + { |
| 58 | + args.IsCancelled = true;// the general approach for cancelling an event |
| 59 | + } |
| 60 | +
|
| 61 | + Console.WriteLine("Edit event is fired."); |
| 62 | + } |
| 63 | +
|
| 64 | + async Task UpdateHandler(GridCommandEventArgs args) |
| 65 | + { |
| 66 | + SampleData item = (SampleData)args.Item; |
| 67 | +
|
| 68 | + // perform actual data source operations here through your service |
| 69 | + await MyService.Update(item); |
| 70 | +
|
| 71 | + // update the local view-model data with the service data |
| 72 | + await GetGridData(); |
| 73 | +
|
| 74 | + Console.WriteLine("Update event is fired."); |
| 75 | + } |
| 76 | +
|
| 77 | + async Task DeleteHandler(GridCommandEventArgs args) |
| 78 | + { |
| 79 | + SampleData item = (SampleData)args.Item; |
| 80 | +
|
| 81 | + // perform actual data source operation here through your service |
| 82 | + await MyService.Delete(item); |
| 83 | +
|
| 84 | + // update the local view-model data with the service data |
| 85 | + await GetGridData(); |
| 86 | +
|
| 87 | + Console.WriteLine("Delete event is fired."); |
| 88 | + } |
| 89 | +
|
| 90 | + async Task CreateHandler(GridCommandEventArgs args) |
| 91 | + { |
| 92 | + SampleData item = (SampleData)args.Item; |
| 93 | +
|
| 94 | + // perform actual data source operation here through your service |
| 95 | + await MyService.Create(item); |
| 96 | +
|
| 97 | + // update the local view-model data with the service data |
| 98 | + await GetGridData(); |
| 99 | +
|
| 100 | + Console.WriteLine("Create event is fired."); |
| 101 | + } |
| 102 | +
|
| 103 | + async Task CancelHandler(GridCommandEventArgs args) |
| 104 | + { |
| 105 | + SampleData item = (SampleData)args.Item; |
| 106 | +
|
| 107 | + // if necessary, perform actual data source operation here through your service |
| 108 | +
|
| 109 | + Console.WriteLine("Cancel event is fired."); |
| 110 | + } |
| 111 | +
|
| 112 | +
|
| 113 | + // in a real case, keep the models in dedicated locations, this is just an easy to copy and see example |
| 114 | + public class SampleData |
| 115 | + { |
| 116 | + public int ID { get; set; } |
| 117 | + [Required] |
| 118 | + public string Name { get; set; } |
| 119 | + } |
| 120 | +
|
| 121 | + public List<SampleData> MyData { get; set; } |
| 122 | +
|
| 123 | + async Task GetGridData() |
| 124 | + { |
| 125 | + MyData = await MyService.Read(); |
| 126 | + } |
| 127 | +
|
| 128 | + protected override async Task OnInitializedAsync() |
| 129 | + { |
| 130 | + await GetGridData(); |
| 131 | + } |
| 132 | +
|
| 133 | + // the following static class mimics an actual data service that handles the actual data source |
| 134 | + // replace it with your actual service through the DI, this only mimics how the API can look like and works for this standalone page |
| 135 | + public static class MyService |
| 136 | + { |
| 137 | + private static List<SampleData> _data { get; set; } = new List<SampleData>(); |
| 138 | +
|
| 139 | + public static async Task Create(SampleData itemToInsert) |
| 140 | + { |
| 141 | + itemToInsert.ID = _data.Count + 1; |
| 142 | + _data.Insert(0, itemToInsert); |
| 143 | + } |
| 144 | +
|
| 145 | + public static async Task<List<SampleData>> Read() |
| 146 | + { |
| 147 | + if (_data.Count < 1) |
| 148 | + { |
| 149 | + for (int i = 1; i < 50; i++) |
| 150 | + { |
| 151 | + _data.Add(new SampleData() |
| 152 | + { |
| 153 | + ID = i, |
| 154 | + Name = "Name " + i.ToString() |
| 155 | + }); |
| 156 | + } |
| 157 | + } |
| 158 | +
|
| 159 | + return await Task.FromResult(_data); |
| 160 | + } |
| 161 | +
|
| 162 | + public static async Task Update(SampleData itemToUpdate) |
| 163 | + { |
| 164 | + var index = _data.FindIndex(i => i.ID == itemToUpdate.ID); |
| 165 | + if (index != -1) |
| 166 | + { |
| 167 | + _data[index] = itemToUpdate; |
| 168 | + } |
| 169 | + } |
| 170 | +
|
| 171 | + public static async Task Delete(SampleData itemToDelete) |
| 172 | + { |
| 173 | + _data.Remove(itemToDelete); |
| 174 | + } |
| 175 | + } |
| 176 | +} |
| 177 | +```` |
| 178 | + |
| 179 | +## Use a Custom Validator |
| 180 | + |
| 181 | +You can validate the Grid with any validator that uses the `EditContext`. To change the default validator, add a `<ValidatorTemplate>` tag in `<GridSettings>`. Define the custom validator in the `ValidatorTemplate`. |
| 182 | + |
| 183 | +## See Also |
| 184 | + |
| 185 | + * [Grid Editing]({%slug components/grid/editing/overview%}) |
| 186 | + |
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