当我尝试使用C#Lambda扩展方法All时,我收到以下错误

Question

private void EnsureCurrentlyValid()
{
    //I'm valid if IDataErrorInfo.this[] returns null for every property
    var propsToValidate = new[] { "Name", "Email", "Phone", "WillAttend" };
    bool isValid = propsToValidate.All(x => this[x] == null);
    if (!isValid)
        throw new InvalidOperationException("Can't submit invalid GuestResponse");
}

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'System.Array'不包含'All'的定义,并且没有扩展方法'All'接受类型'System.Array'的第一个参数可以找到(你是否缺少using指令或汇编引用？)C:\dev的\ ASPNET\PartyInvites \型号\ GuestResponse.cs

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我错过了什么？

Answer 1

将其添加到您的文件顶部:

using System.Linq;