blazor server | how to get a parameter value from a child component?

Question

User2110873642 posted

how to get the 'CaptchaCompleted' parameter value from a child component?

parent

<CaptchaCheck ID="C1" />

<input type="button" value="Login" @onclick="Login" />

@code{
    private async void Login()
    {
        if (C1.CaptchaCompleted)
        {

        }
    }

Child  ( CaptchaCheck.razor )

@code {
   [Parameter]
   public bool CaptchaCompleted { get; set; } = false;
}

Answer 1

User475983607 posted

Either make use of event handlers to pass the state of the CaptchaCheck results to the parent page or reference the state of CaptchaCheck from the parent page.

See the Blazor component docs.

https://docs.microsoft.com/en-us/aspnet/core/blazor/components/?view=aspnetcore-3.1

https://docs.microsoft.com/en-us/aspnet/core/blazor/components/?view=aspnetcore-3.1#capture-references-to-components

Answer 2

User-474980206 posted

the best is that CaptchaCheck has an  event that the parent can use to update its state. This is cleaner than using Cascading state.

<CaptchaCheck ID="C1" onVerify="@((v) => CaptchaCompleted = v)" />

<input type="button" value="Login" @onclick="Login" />

@code{
    [Parameter]
    public bool CaptchaCompleted { get; set; } = false;

    private async void Login()
    {
        if (CaptchaCompleted)
        {

        }
    }

in the Captacha component just define:

    [Parameter] public EventCallback<bool> OnVerify { get; set; }

and somewhere call:

  OnVerify.InvokeAsync(verifyStatus);

see event handling:

https://docs.microsoft.com/en-us/aspnet/core/blazor/components/event-handling?view=aspnetcore-3.1