我有一个父页面，在那里我有:
<CascadingValue Value="SelectedAddress">
<CollectionAddress VendorNumber="@VendorNumber"></CollectionAddress>
</CascadingValue>
而这背后的代码有:
public AddressDTO SelectedAddress { get; set; } = new AddressDTO();
我的子组件具有
[CascadingParameter]
protected AddressDTO? SelectedAddress { get; set; }
在子组件中，我设置了SelectedAddress，但当我切换回父组件时，SelectedAddress为空.如果我用错了，这是我第一次try 使用级联参数.
实际上情况正好相反.CascadingValue用于将数据从父组件发送给子组件(通常向下多个级别).如果要将数据从子对象发送到父对象，请使用EventCallback参数，如下所示:
@page "/"
<CollectionAddress AddressChanged="AddressRecieved" />
@addressStree
@code {
private string addressStree;
public AddressDTO SelectedAddress { get; set; } = new AddressDTO()
{
Street = "Garden"
};
private async Task AddressRecieved(AddressDTO address)
{
addressStree = address.Street;
}
}
<h3>Collection Address</h3>
<button @onclick="SendAddress">Change Adddress</button>
@code {
//[CascadingParameter]
//protected AddressDTO? SelectedAddress { get; set; }
[Parameter]
public EventCallback<AddressDTO> AddressChanged { get; set; }
private async void SendAddress()
{
await AddressChanged.InvokeAsync(new AddressDTO { Street = "Garden" });
}
}
public class AddressDTO
{
public string? Street { get; set; }
}