如何访问EditForm中单个字段的验证？

问题描述

我想根据<EditForm />中的验证结果来处理CSS。

我的简化形式如下

<EditForm Model="Registration" OnValidSubmit="Submit">
    <label for="input-username">Username</label>
    <InputText id="input-username" 
               type="text" 
               class="???" 
               @bind-Value="Registration.Username" />
    <p>
        <ValidationMessage For="@(() => Registration.Username)" />
    </p>
</EditForm>

我的表单没有比此表单更多的字段，因此我只想过滤Registration.Username的验证，只编辑#input-username的css类。

解决方法

您可以订阅EditContext对象的OnFieldChanged事件，找出哪个字段已更改并采取相应措施。

<EditForm EditContext="EditContext" OnValidSubmit="Submit">
    <DataAnnotationsValidator />

     <label for="input-username">Username</label>
    <InputText id="input-username" type="text" class="MyUsername" 
               @bind-Value="Registration.Username" />
    <p>
        <ValidationMessage For="@(() => Registration.Username)" />
    </p>
            <button type="submit">Submit</button>
        
</EditForm>

@code
{
    private Registration Model = new Registration();
    private EditContext EditContext;
    private string MyUsername = "InitialCssClass";

    protected override void OnInitialized()
    {
        EditContext = new EditContext(Model);

        EditContext.OnFieldChanged += EditContext_OnFieldChanged;

    }

    private void EditContext_OnFieldChanged(object sender,FieldChangedEventArgs e)
    {
         if (e.FieldIdentifier.FieldName == nameof(Model.Username))
         {
             MyUsername = "Set here a new class name,etc.";
         }
    }
}