Radzen Dropdown error when binding multiple int value

Radzen.Blazor Components
#1

Hello i have trouble with binding int multiple data to multiple values. I have this variable
IEnumerable multipleValues;

So im using this component

RadzenDropDown Disabled="@DisableArpDropDown" AllowClear="true" TValue="int"
LoadData=@LoadDataVirtualization AllowFiltering="true"
Data=@StudentList
TextProperty="Name"
@bind-Value=@multipleValues
Multiple="true"
ValueProperty="Id"
SelectedItemChanged=@(args => OnChange(args, "DropDown with multiple selection"))

My model is looks like that

public int? Id { get; set; }
public string Name { get; set; }

error CS1662: Cannot convert lambda expression to intended delegate type because some of the return types in the block are not implicitly convertible to the delegate return type

I found this link DropDown Multiple with integer value example is working fine for me but my component and code doesn't work i can't understand why.

#2

Can you provide a complete example which reproduces the problem? Also please format your code according to the FAQ.

#3

My variables are created like this
IEnumerable SelectedStudentIdList;
private List StudentList = new List();

I have this component
<RadzenDropDown Name="StudentDropdown" Disabled="@DisableStudentDropDown" AllowClear="true"
LoadData=@LoadDataVirtualization AllowFiltering="true"
Data=@(StudentList)
TextProperty="Name"
Multiple="true"
ValueProperty="Id"
@bind-Value="@SelectedStudentIdList"/>

My load data event is this

public async Task LoadDataVirtualization(LoadDataArgs args)
{
Console.WriteLine("Args:" + args.Filter);
StudentList = await StudentService.GetStudentList(args.Filter);
await InvokeAsync(StateHasChanged);
}

My errors are look like this

image
image1178×513 33.9 KB

So story is im getting input value from user and that is args.Filter value. Im passing that value to api so its brings the related students. I want to select those students but bind their id to SelectedStudentIdList. After i select my students and click outside component this error shows up.

#4

Unfortunately you neither formatted your code nor provided a complete example. I won't be able to assist.

1 Like
#5

As @korchev said, it's impossible to really understand what's going on in your code, if you don't provide a full example and properly formatted code snippet.

However, I can see that the Id in your model is a nullable int:

public int? Id { get; set; }.

That's probably causing problems. I can't imagine why an "Id" should be nullable, so I think you should work your code around to make that property not nullable.

1 Like
#6

Sorry for late answer but yes that was the source of the error. Im embarrassed stealing your time for asking a question like this. Actually i did not define these Models and variables so i asked myself why someone define Id as nullable :slight_smile: anyway thank you.