C# Distinct未为表提供Distinct行

Distinct未为表提供Distinct行

 ObjectParameter statusCode = new ObjectParameter("StatusCode", typeof(int));
 ObjectParameter statusMessage = new ObjectParameter("StatusMessage", typeof(string));
 return Context.p_Countries_List(userName, statusCode, statusMessage)
              .Select(c => new Countries_List_ResultModel()
            {
                currency = c.currency
            }).Distinct().ToList();

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您必须重写

Equals

，以便

Distinct

知道如何区分一个实例和另一个实例

public class Countries_List_ResultModel
{
    public override bool Equals(object obj)
    {
        var item = obj as Countries_List_ResultModel;

        if (item == null)
        {
            return false;
        }

        return true; // Add the appropriate logic.
    }

    public override int GetHashCode()
    {
        // Return the hashcode to quickly identify different instances.
        return this.currency.GetHashCode();
    }
}

---

更多信息。

有两个

Distinct

方法重载：

Distinct<TSource>(this IEnumerable<TSource> source);
Distinct<TSource>(this IEnumerable<TSource> source, IEqualityComparer<TSource> comparer);

---

我找到了答案，这是有效的

        ObjectParameter statusCode = new ObjectParameter("StatusCode", typeof(int));
        ObjectParameter statusMessage = new ObjectParameter("StatusMessage", typeof(string));
        return Context.p_Currencies_List(userName, statusCode, statusMessage).Distinct().Select(c => new Countries_List_ResultModel()
        {
            currency = c
        }).ToList();

---

…命名惯例，为什么要放弃标准的C#one<代码>货币是唯一设置的属性吗？

        ObjectParameter statusCode = new ObjectParameter("StatusCode", typeof(int));
        ObjectParameter statusMessage = new ObjectParameter("StatusMessage", typeof(string));
        return Context.p_Currencies_List(userName, statusCode, statusMessage).Distinct().Select(c => new Countries_List_ResultModel()
        {
            currency = c
        }).ToList();