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533
VisualizaçõesElementReference to conditionally created element in Blazor
I'm trying to set focus to input control which is conditionally rendered. I'm setting ElementReference but it's id and context are both null.
<button @onclick="ToggleInput">Show input</button>
@if(showInput) {
<input @ref="inputRef" type="text"/>
}
@code {
private ElementReference inputRef;
private bool showInput;
async void ToggleInput() {
showInput = !showInput;
await inputRef.FocusAsync();
}
}
When I press the button it shows this error in console:
System.InvalidOperationException: ElementReference has not been configured correctly
Full error message:
Working example with error https://blazorrepl.com/repl/wbueaMPK28hf2NNv09
3 Respostas
Responde à pergunta0
This seems to work and didn't have to be a separate component. I stuck it right on the start page.
<button @onclick="ToggleInput">Show input</button>
@if (showInput)
{
<input @ref="inputRef" type="text" />
}
@code {
private ElementReference inputRef;
private bool showInput;
protected async override Task OnAfterRenderAsync(bool firstRender)
{
if (showInput) await inputRef.FocusAsync();
}
void ToggleInput()
{
showInput = !showInput;
}
}
0
Move the input box to another component. Then you can then hook into the lifecycle of the component and call .FocusAsync after it has rendered.
0
It's not the perfect solution either, more like a workaround, but the following worked for me:
<button @onclick="ToggleInput">Show input</button>
@if(showInput) {
<input @ref="inputRef" type="text"/>
}
@code {
private ElementReference inputRef;
private bool showInput;
async void ToggleInput() {
showInput = !showInput;
StateHasChanged();
await Task.Run(() =>
{
if(inputRef.Context != null) inputRef.FocusAsync();
});
}
}
In my tests, the context was never null, so it probably wouldn't need the check. But I prefer that the focus is not set than that an exception would be thrown.