当TextChanged时Blazor InputText调用异步方法

问题描述

我尝试捕获Blazor(ServerSide)中InputText的文本更改，然后调用一个异步方法来检查输入是否正确的优惠券代码.

I try to capture text changes of InputText in Blazor (ServerSide) and then call a async method to check if input is correct coupon code or not.

HTML:

<EditForm Model="@Basket" OnValidSubmit="@CommitBasket">
    Gutscheincode
    <InputText class="coupon-input checkout-control pristine untouched" 
            @bind-Value="CouponCode"
            @onchange="CouponCodeChanged">
    </InputText>
    @CouponText
</EditForm>`

但是未引发CouponCodeChanged-OnKeyUp没用，因为在该状态下文本值未更改...

But The CouponCodeChanged isn't raised - OnKeyUp is not useful because the Text Value isn't changed at that state...

这是C#方法:

public async Task CouponCodeChanged(ChangeEventArgs args)
{
    using var client = ClientFactory.CreateClient();
    var result = await ApiCalls.GetCouponCodeData(client, AppState.BaseUrl, 2, CouponCode);
    CouponText = result== null ? "NOT FOUND" : $"exists:{result.Exists} amount:{result.Amount}";
}

有人有提示或想法如何方便地解决该问题吗?

Has anyone a hint or idea how to solve that in a convinient way?

谢谢！

推荐答案

InputText 组件没有 onchange 事件，但没有 ValueChanged .
但是，如果要预订此事件，则需要传递 ValueExpression ，这并不容易.我发现预订此事件最简单的方法是覆盖 InputText 组件.

InputText component doesn't have a onchange event but ValueChanged.
However, if you want to subscribe to this event you need to pass a ValueExpression and it's not easy.The easiest I found to subscribe to this event is to override the InputText component.

CouponComponent.razor

@inherits InputText
<InputText class="coupon-input checkout-control pristine untouched" 
                   ValueExpression="ValueExpression" Value="@Value" ValueChanged="OnValueChanged" />
@code {
  [Parameter]
  public EventCallback<string> CouponValueChanged { get; set; }

  private async Task OnValueChanged(string value)
  {
     await ValueChanged.InvokeAsync(value);
     using var client = ClientFactory.CreateClient();
     var result = await ApiCalls.GetCouponCodeData(client, AppState.BaseUrl, 2, CouponCode);
     var coupon = result == null ? "NOT FOUND" : $"exists:{result.Exists} amount:{result.Amount}"
     await CouponValueChanged.InvokeAsync(coupon);
  }
}

用法

<EditForm Model="@Basket" OnValidSubmit="@CommitBasket">
    Gutscheincode
    <CouponComponent @bind-Value="CouponCode"
        @CouponValueChanged="CouponCodeChanged">
    </InputText>
    @CouponText
</EditForm>

@code {
   private void CouponCodeChanged(string coupon)
   {
      CouponText = coupon;
      StateHasChanged();
   }
}

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