RadzenDropDown don`t work

Radzen.Blazor Components
1

Help my please. Why RadzenDropDown don`t work in my app?
(I'm sorry for my English)

<RadzenDropDown AllowClear="true" AllowFiltering="true" 
                @bind-Value=@Book.Genres Multiple="true" Placeholder="Select..." Data=@genres TextProperty="Name" ValueProperty="Id"
                Style="width:300px" />


@code {
    IEnumerable<Genre> genres = new List<Genre>();
    [Parameter] public Book Book { get; set; } = new Book();
    protected async override Task OnInitializedAsync()
    {
        bookAuthor = Book.Autor;
        genres = await GenreService.GetAllGenres();
    }
}

 public class Genre
    {
        public int Id { get; set; }
        [Required]
        public string Name { get; set; }
        public List<Book> Books { get; set; } = new List<Book>();
    }

public class Book
{
public int Id { get; set; }
[Required]
[Range(1, int.MaxValue)]
public int NumberOfPages { get; set; }

    [Required]
    [Range(1, int.MaxValue)]
    public double Price { get; set; }
    [Required]
    public string Name { get; set; }
    [Required]
    public DateTime DateOfCreate { get; set; }
    [Required]
    public string Description { get; set; }
    [Required]
    public string Picture { get; set; }
    public Author Autor { get; set; }
    public int AutorId { get; set; }
    public List<Genre> Genres { get; set; }
}
2

Error
blazor.webassembly.js:1 crit: Microsoft.AspNetCore.Components.WebAssembly.Rendering.WebAssemblyRenderer[100]
Unhandled exception rendering component: Specified cast is not valid.
System.InvalidCastException: Specified cast is not valid.
at Radzen.DropDownBase1.<SelectAll>d__45[[System.Collections.Generic.List1[[BookStore.Shared.Models.Genre, BookStore.Shared, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null]], System.Private.CoreLib, Version=5.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e]].MoveNext()
at Microsoft.AspNetCore.Components.ComponentBase.CallStateHasChangedOnAsyncCompletion(Task task)
at Microsoft.AspNetCore.Components.RenderTree.Renderer.GetErrorHandledTask(Task taskToHandle)

3

Hello,

IEnumerable<string> multipleValues = new string[] {};

<RadzenDropDown AllowClear="true" AllowFiltering="true" 
                @bind-Value=@multipleValues Multiple="true" Placeholder="Select..." Data=@genres TextProperty="Name" ValueProperty="Id"
                Style="width:300px" />

Try the above setting for bind-Value for further details check this link

1 Like
4

thank you. My mistake in type of bind-Value should be like type of ValueProperty.