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Limit input in a grid row by character count

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Kieran
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Kieran asked on 12 Dec 2020, 05:52 PM

 

Hi,

In my Telerik Blazor grid, I'm looking to limit the amount of characters a user can input in a particular column.  

So in my column below I want the user only to be able to enter max 50 characters when they are adding or updating a row.

 <GridColumn Field="Description">
                        <Template>
                            @((context as Model1).Desc.ToString())
                        </Template>
</GridColumn>

Thanks for any pointers!

 

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Svetoslav Dimitrov
Telerik team
answered on 14 Dec 2020, 03:11 PM

Hello Kieran,

You can take advantage of the item passed to your handler for the Create and Update operations to limit the number of characters. Below, I have made a sample implementation. If the length of the string is more than 50 when creating a new item a Notification component will appear. Could you give this example a try and see if it works as expected for you. If it does not you could follow up on our discussion so I can suggest a different approach.

Editing is cancelled for the first two records.
<br />
<strong>There is a deliberate delay</strong> in the data source operations in this example to mimic real life delays and to showcase the async nature of the calls.

<TelerikNotification @ref="@NotificationReference"></TelerikNotification>

<TelerikGrid Data=@MyData EditMode="@GridEditMode.Inline" Pageable="true" Height="400px"
             OnUpdate="@UpdateHandler" OnEdit="@EditHandler" OnDelete="@DeleteHandler" OnCreate="@CreateHandler" OnCancel="@CancelHandler">
    <GridToolBar>
        <GridCommandButton Command="Add" Icon="add">Add Employee</GridCommandButton>
    </GridToolBar>
    <GridColumns>
        <GridColumn Field=@nameof(SampleData.ID) Title="ID" Editable="false" />
        <GridColumn Field=@nameof(SampleData.Name) Title="Name" />
        <GridCommandColumn>
            <GridCommandButton Command="Save" Icon="save" ShowInEdit="true">Update</GridCommandButton>
            <GridCommandButton Command="Edit" Icon="edit">Edit</GridCommandButton>
            <GridCommandButton Command="Delete" Icon="delete">Delete</GridCommandButton>
            <GridCommandButton Command="Cancel" Icon="cancel" ShowInEdit="true">Cancel</GridCommandButton>
        </GridCommandColumn>
    </GridColumns>
</TelerikGrid>

@logger

@code {
    public TelerikNotification NotificationReference { get; set; }

    async Task EditHandler(GridCommandEventArgs args)
    {
        SampleData item = (SampleData)args.Item;

        //prevent opening for edit based on condition
        if (item.ID < 3)
        {
            args.IsCancelled = true;//the general approach for cancelling an event
        }

        AppendToLog("Edit", args);
    }

    async Task UpdateHandler(GridCommandEventArgs args)
    {
        AppendToLog("Update", args);

        SampleData item = (SampleData)args.Item;

        // perform actual data source operations here through your service
        await MyService.Update(item);

        // update the local view-model data with the service data
        await GetGridData();
    }

    async Task DeleteHandler(GridCommandEventArgs args)
    {
        AppendToLog("Delete", args);

        SampleData item = (SampleData)args.Item;

        // perform actual data source operation here through your service
        await MyService.Delete(item);

        // update the local view-model data with the service data
        await GetGridData();

    }

    async Task CreateHandler(GridCommandEventArgs args)
    {
        AppendToLog("Create", args);

        SampleData item = (SampleData)args.Item;

        if(item.Name.Length > 50)
        {
            NotificationReference.Show(new NotificationModel()
            {
                Text = $"The lenght of the Name is too long. Max 50 characters",
                ThemeColor = "error",
                Closable = true,
                CloseAfter = 0
            });
        }
        else
        {
            // perform actual data source operation here through your service
            await MyService.Create(item);

            // update the local view-model data with the service data
            await GetGridData();
        }
    }

    async Task CancelHandler(GridCommandEventArgs args)
    {
        AppendToLog("Cancel", args);

        SampleData item = (SampleData)args.Item;

        // if necessary, perform actual data source operation here through your service

        await Task.Delay(1000); //simulate actual long running async operation
    }

    // this method and field just display what happened for visual cues in this example

    MarkupString logger;
    void AppendToLog(string commandName, GridCommandEventArgs args)
    {
        string currAction = string.Format(
            "<br />Command: <strong>{0}</strong>; is cancelled: <strong>{1}</strong>; is the item new: <strong>{2}</strong>",
                commandName,
                args.IsCancelled,
                args.IsNew
            );
        logger = new MarkupString(logger + currAction);
    }


    // in a real case, keep the models in dedicated locations, this is just an easy to copy and see example
    public class SampleData
    {
        public int ID { get; set; }
        public string Name { get; set; }
    }

    List<SampleData> MyData { get; set; }

    async Task GetGridData()
    {
        MyData = await MyService.Read();
    }

    protected override async Task OnInitializedAsync()
    {
        await GetGridData();
    }


    // the following static class mimics an actual data service that handles the actual data source
    // replace it with your actual service through the DI, this only mimics how the API will look like and works for this standalone page
    public static class MyService
    {
        private static List<SampleData> _data { get; set; } = new List<SampleData>();

        public static async Task Create(SampleData itemToInsert)
        {
            await Task.Delay(1000); // simulate actual long running async operation

            itemToInsert.ID = _data.Count + 1;
            _data.Insert(0, itemToInsert);
        }

        public static async Task<List<SampleData>> Read()
        {
            await Task.Delay(1000); // simulate actual long running async operation

            if (_data.Count < 1)
            {
                for (int i = 1; i < 50; i++)
                {
                    _data.Add(new SampleData()
                    {
                        ID = i,
                        Name = "Name " + i.ToString()
                    });
                }
            }

            return await Task.FromResult(_data);
        }

        public static async Task Update(SampleData itemToUpdate)
        {
            await Task.Delay(1000); // simulate actual long running async operation

            var index = _data.FindIndex(i => i.ID == itemToUpdate.ID);
            if (index != -1)
            {
                _data[index] = itemToUpdate;
            }
        }

        public static async Task Delete(SampleData itemToDelete)
        {
            await Task.Delay(1000); // simulate actual long running async operation

            _data.Remove(itemToDelete);
        }
    }
}

Regards,
Svetoslav Dimitrov
Progress Telerik

Virtual Classroom, the free self-paced technical training that gets you up to speed with Telerik and Kendo UI products quickly just got a fresh new look + new and improved content including a brand new Blazor course! Check it out at https://learn.telerik.com/.

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Kieran
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answered on 14 Dec 2020, 03:59 PM

 

Hi Svetoslav,

Thanks for the detailed reply.  It works great when they get the notification - except that the row they were trying to add then disappears as the createhandler runs through. 

I would like the user to be able to change the character count of the field to get it below 50 - after they see the notification.  Ideally the row should still be there for them to change until they get the count correct, or they cancel.

Thanks,

Kieran

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Accepted
Svetoslav Dimitrov
Telerik team
answered on 16 Dec 2020, 10:12 AM

Hello Kieran,

You can achieve this behavior by using our PopUp editing mode for the Grid. When the window opens and the user types a name longer than 50 characters a Validation message would appear and the window will not be closed until the string passes certain conditions. Would this be a suitable solution for your application? Below, I have put a sample implementation which you can give a try. Get back to me if I could further assist you.

@using System.ComponentModel.DataAnnotations
@* Used for the model annotations only *@

<strong>Editing is cancelled for the first two records.</strong>

<TelerikGrid Data=@MyData EditMode="@GridEditMode.Inline" Pageable="true" Height="500px"
             OnUpdate="@UpdateHandler" OnEdit="@EditHandler" OnDelete="@DeleteHandler" OnCreate="@CreateHandler" OnCancel="@CancelHandler">
    <GridToolBar>
        <GridCommandButton Command="Add" Icon="add">Add Employee</GridCommandButton>
    </GridToolBar>
    <GridColumns>
        <GridColumn Field=@nameof(SampleData.ID) Title="ID" Editable="false" />
        <GridColumn Field=@nameof(SampleData.Name) Title="Name" />
        <GridCommandColumn>
            <GridCommandButton Command="Save" Icon="save" ShowInEdit="true">Update</GridCommandButton>
            <GridCommandButton Command="Edit" Icon="edit">Edit</GridCommandButton>
            <GridCommandButton Command="Delete" Icon="delete">Delete</GridCommandButton>
            <GridCommandButton Command="Cancel" Icon="cancel" ShowInEdit="true">Cancel</GridCommandButton>
        </GridCommandColumn>
    </GridColumns>
</TelerikGrid>

@code {
    void EditHandler(GridCommandEventArgs args)
    {
        SampleData item = (SampleData)args.Item;

        // prevent opening for edit based on condition
        if (item.ID < 3)
        {
            args.IsCancelled = true;// the general approach for cancelling an event
        }

        Console.WriteLine("Edit event is fired.");
    }

    async Task UpdateHandler(GridCommandEventArgs args)
    {
        SampleData item = (SampleData)args.Item;

        // perform actual data source operations here through your service
        await MyService.Update(item);

        // update the local view-model data with the service data
        await GetGridData();

        Console.WriteLine("Update event is fired.");
    }

    async Task DeleteHandler(GridCommandEventArgs args)
    {
        SampleData item = (SampleData)args.Item;

        // perform actual data source operation here through your service
        await MyService.Delete(item);

        // update the local view-model data with the service data
        await GetGridData();

        Console.WriteLine("Delete event is fired.");
    }

    async Task CreateHandler(GridCommandEventArgs args)
    {
        SampleData item = (SampleData)args.Item;

        // perform actual data source operation here through your service
        await MyService.Create(item);

        // update the local view-model data with the service data
        await GetGridData();

        Console.WriteLine("Create event is fired.");
    }

    async Task CancelHandler(GridCommandEventArgs args)
    {
        SampleData item = (SampleData)args.Item;

        // if necessary, perform actual data source operation here through your service

        Console.WriteLine("Cancel event is fired.");
    }

    // in a real case, keep the models in dedicated locations, this is just an easy to copy and see example
    public class SampleData
    {
        public int ID { get; set; }

        [Required(ErrorMessage = "The employee must have a name")]
        [MaxLength(50, ErrorMessage = "Max lenght of the name is 50 characters")]
        public string Name { get; set; }
    }

    public List<SampleData> MyData { get; set; }

    async Task GetGridData()
    {
        MyData = await MyService.Read();
    }

    protected override async Task OnInitializedAsync()
    {
        await GetGridData();
    }

    // the following static class mimics an actual data service that handles the actual data source
    // replace it with your actual service through the DI, this only mimics how the API can look like and works for this standalone page
    public static class MyService
    {
        private static List<SampleData> _data { get; set; } = new List<SampleData>();

        public static async Task Create(SampleData itemToInsert)
        {
            itemToInsert.ID = _data.Count + 1;
            _data.Insert(0, itemToInsert);
        }

        public static async Task<List<SampleData>> Read()
        {
            if (_data.Count < 1)
            {
                for (int i = 1; i < 50; i++)
                {
                    _data.Add(new SampleData()
                    {
                        ID = i,
                        Name = "Name " + i.ToString()
                    });
                }
            }

            return await Task.FromResult(_data);
        }

        public static async Task Update(SampleData itemToUpdate)
        {
            var index = _data.FindIndex(i => i.ID == itemToUpdate.ID);
            if (index != -1)
            {
                _data[index] = itemToUpdate;
            }
        }

        public static async Task Delete(SampleData itemToDelete)
        {
            _data.Remove(itemToDelete);
        }
    }
}

Regards,
Svetoslav Dimitrov
Progress Telerik

Virtual Classroom, the free self-paced technical training that gets you up to speed with Telerik and Kendo UI products quickly just got a fresh new look + new and improved content including a brand new Blazor course! Check it out at https://learn.telerik.com/.

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Kieran
Top achievements
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answered on 17 Dec 2020, 08:53 AM

 

Thanks Svetoslav.  That worked great with the popup edit mode too.

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Svetoslav Dimitrov
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Kieran
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