Get text of Selected Item in Drop Down List

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This topic has 1 reply, 2 voices, and was last updated 2 years ago by svetoslav_borislavov.

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October 8, 2023 at 2:51 pm #108902

salasidis
Participant

I am using Blazor Version

the declaration in HTML is

<DropDownList @ref=”EWDeviceList” SelectedIndexes=”selectedIndexes” OnChange=”ChangeDevice” />

The code in @code is

private async void ChangeDevice(Event chEv)
{
//ListBoxChangeEventDetail detail = chEv[“Detail”] as ListBoxChangeEventDetail;

if (dpData != null)
{
dpData.Clear();
}
// add dev par data

string devNm = EWDeviceList.SelectedValues[0].ToString();

}

The event always fire twice, and although the value is correct the first time, on firing again, it resets the drop down list to the first element. This does not happen if I remove the …SelectedValues[0]… part of the code.

I looked for an example of OnChanged with the DropDownList on the Documentation, but could not find one.

Thanks

October 9, 2023 at 5:46 am #108907

svetoslav_borislavov
Participant

Hi,

This is happening because you have passed selectedIndexes.
In the OnChange you should change the selected indexes to match the current index.

Here is the fixed version:
<DropDownList @ref=”EWDeviceList” SelectedIndexes=”@selectedIndexes” OnChange=”ChangeDevice” DataSource=”@dataSource”/>

@code
{
DropDownList EWDeviceList = default!;

string[] dataSource = new string[] { “One”, “Two” };

int[] selectedIndexes = new int[] { 1 };

private async void ChangeDevice(Event chEv)
{
DropDownListChangeEventDetail detail = chEv[“Detail”];

selectedIndexes = new int[] { detail.Index };

string devNm = EWDeviceList.SelectedValues[0].ToString();

}
}

I hope this helps!

Best Regards,
Svetoslav Borislavov

Smart UI Team
https://www.htmlelements.com/
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svetoslav_borislavov · Accepted Answer

Hi,

This is happening because you have passed selectedIndexes.
In the OnChange you should change the selected indexes to match the current index.

Here is the fixed version:
<DropDownList @ref="EWDeviceList" SelectedIndexes="@selectedIndexes" OnChange="ChangeDevice" DataSource="@dataSource"/>

@code
{
    DropDownList EWDeviceList = default!;

string[] dataSource = new string[] { "One", "Two" };

int[] selectedIndexes = new int[] { 1 };

private async void ChangeDevice(Event chEv)
        {
            DropDownListChangeEventDetail detail = chEv["Detail"];

selectedIndexes = new int[] { detail.Index };

string devNm = EWDeviceList.SelectedValues[0].ToString();

}
}

I hope this helps!

Best Regards,
Svetoslav Borislavov

Smart UI Team
https://www.htmlelements.com/