Optional Select TValue

[Zumpel96]

Hello. I have a Select, which contains a List of Companies. Anyway, From the EF, I therefore have a nullable Property int? CompanyId, because I want that value to be optional. I need this to be null and not 0, because otherwise EF will look for a reference of the ID 0, which is not contained within my database and throw an exception. How can I depict this properly in Blazorise? If I set the TValue of the Select to int? everything works, but I need an element in the List, with the value null. Therefore, the following code does not work:

<Select TValue="int?" @bind-SelectedValue="@Data.CompanyId">
    <SelectItem Value="@null">@L["NoSelectedCompany"]</SelectItem>
    @foreach (var company in companies)
    {
        <SelectItem Value="@company.Id">@company.Name</SelectItem>
    }
</Select>

[stsrki]

You need to define TValue so that it matches with TValue from the parent Select. This might also work <SelectItem Value="@((int?)null)">@L["NoSelectedCompany"]</SelectItem>.

[Zumpel96]

Thanks, with the cast it works. Anyways, it seems, that the SelectedValueChanged is not triggered. To test it, I changed my code to:

<Select TValue="int?" SelectedValue="@Data.CompanyId" SelectedValueChanged="TestValueChanged">
    <SelectItem TValue="int?" Value="null">@L["NoSelectedCompany"]</SelectItem>
    @foreach (var company in companies)
    {
        <SelectItem Value="@company.Id">@company.Name</SelectItem>
    }
</Select>

public void TestValueChanged(int? i)
{
    this.Data.CompanyId = i;
}

If I set a breakpoint into the line this.Data.CompanyId = i it gets triggered when a non-null value is set. When I select the null-value, the breakpoint does not trigger. I also don't get any additional warnings or errors.

[stsrki]

The null or empty option element has a strange behavior. It is a known issue, and it is how it works on browsers. You can try searching on our issues list for more info, eg. #185

In the meantime try with <SelectItem TValue="int?" Value="null"></SelectItem>

[Zumpel96]

Oh I see. Thanks for the issue list. Sadly <SelectItem TValue="int?" Value="null">@L["NoSelectedCompany"]</SelectItem> has the same behavior. I'll try to find a workaround until then.

[stsrki]

Did you remove @L["NoSelectedCompany"] from the SelectItem content?