RadzenGrid Reload in async context

Radzen.Blazor Components
1

Hi everyone,

i am using the RadzenGrid as followed

<RadzenGrid @ref="userGrid" TItem="Account" Data="listOfUsers" Value="account" RowSelect="@(arg => account = arg)">
    <Columns>
    <RadzenGridColumn TItem="Account" Property="Id" Title="Id" />
    <RadzenGridColumn TItem="Account" Property="UserName" Title="Benutzername" />
    </Columns>
    </RadzenGrid>

My DatabaseContext i inject by IdbContextFactory like that:

@inject IDbContextFactory<DatabaseContext> DbFactory

@code {
protected override async Task OnInitializedAsync()
    {
        using (var dbContext = DbFactory.CreateDbContext())
        {
            account = await dbContext.Users.Include(x => x.UserRoles).ThenInclude(y => y.Role).FirstOrDefaultAsync();
            listOfUsers = await dbContext.Users.ToListAsync();
        }
        await base.OnInitializedAsync();
    }
}

If something in my "listOfUsers" Collection then i want to "reload" it, but because i can't use the "Users"-DbSet its not reloading.
Do you guys have any idea to solve that?

Enjoy your help! Thanks!

2

If you want to reload the listOfUsers collection from your database you have to read it again from the dbContext. There is no way around that.

3

Thanks @korchev for your replay. The Problem i've with that solution is, that when i'm reassign the listOfUsers the selected account of the DataGrid gets unselect. Do i have to clear the existing list instead of reassign it?

4

Hi @JoeGER94,

Try persisting the selection of your RadzenGrid by using @bind-Value.

<RadzenGrid @bind-Value=@selection ...>

@code {
     object selection;
}

We recommend updating your application to use the newer RadzenDataGrid though.

5

Hey @korchev,

i did a lot of testing now and i updated to the current Version as you recommended.

<RadzenDataGrid @ref="usersGrid" TItem="Account" Data="listOfAccounts" @bind-Value="selectedAccountsList" RowSelect="@(args => OnRowSelected(args))" SelectionMode="DataGridSelectionMode.Single">
<Columns>
   <RadzenDataGridColumn TItem="Account" Property="Id" Title="Id" />
   <RadzenDataGridColumn TItem="Account" Property="UserName" Title="Benutzername" />
</Columns>
</RadzenDataGrid>

As soon as i reassign the listOfAccounts with

listOfAccounts = await context.Users.Include(x => x.UserRoles).ThenInclude(x => x.Role).ToListAsync();

the RadzenDataGrid still lose his selectedValue though, however the selectedAccountsList is not empty. To solve this i clear the selectedAccountsList and fill it again. But to do that i need to "cache" the currentSelectedAccounts. It's working but it's not really nice...

I wrote some code if you want to check it:

@if (listOfUsers != null)
{
    <RadzenDataGrid TItem="Account" Data="listOfUsers" @bind-Value="selectedUsers" SelectionMode="DataGridSelectionMode.Single" RowSelect="@(args => RowSelected(args))" RowDeselect="@(args => RowDeselected(args))">
        <Columns>
            <RadzenDataGridColumn TItem="Account" Property="Username" />
        </Columns>
    </RadzenDataGrid>
    <br />
    <RadzenLabel Text="@selectedUsers.FirstOrDefault().Username" />
}

<RadzenButton Text="SomethingChanged" Click=@SomethingChanged />

@code {

    IList<Account> listOfUsers;
    IList<Account> selectedUsers;

    public class Account
    {
        public int Id { get; set; }
        public string Username { get; set; }
    }

    protected override async Task OnInitializedAsync()
    {
        await GenerateSomeTestUsers();
        
        await base.OnInitializedAsync();
    }

    async Task GenerateSomeTestUsers()
    {
        await Task.Run(() =>
        {
            listOfUsers = new List<Account>();
            for (int i = 0; i < 11; i++)
            {
                Account acc = new Account();
                acc.Id = new Random().Next();
                acc.Username = "UserName " + acc.Id;
                listOfUsers.Add(acc);
            }
            selectedUsers = new List<Account>();
            selectedUsers.Add(listOfUsers.FirstOrDefault());
        });
    }

    void RowSelected(Account selected)
    {
        selectedUsers.Clear();
        selectedUsers.Add(selected);
    }

    async Task SomethingChanged()
    {
        await Task.Run(() =>
        {
            listOfUsers = new List<Account>();
            for (int i = 0; i < 11; i++)
            {
                Account acc = new Account();
                acc.Id = new Random().Next();
                acc.Username = "UserName " + acc.Id;
                listOfUsers.Add(acc);
            }
        });
    }
}