如何在类型类的Dictionary中使用ContainsValue [英] How to use ContainsValue in Dictionary of type class

问题描述

我正在创建类的词典，但无法使用"ContainsValue"方法.请帮助

I am creating dictionary of class but I am not able to use "ContainsValue" method. Please help

我的课:

 class clsAttendance
    {
        public string TagId { get; set; }
        public DateTime LastFoundDate { get; set; }
        public DateTime CapturedAt { get; set; }
    }

我的字典:

 private Dictionary<int, clsAttendance> dicAttendance = new Dictionary<int, clsAttendance>();

我想检查字典中是否存在特定的TagId，我这样做是行不通的:

I want to check if particular TagId exists in dictionary or not, I am doing like this but not working:

clsAttendance clsAtt = new clsAttendance();
clsAtt.TagId = 123456AANN;
//---- Check if RFID exists in dictionary or not
bool rfidExists = dicAttendance.ContainsValue(clsAtt);

推荐答案

您的类clsAttendance必须重写Equals或实现IEquatable<clsAttendance>.否则，只有相同的引用才能找到它.始终也覆盖GethashCode.

Your class clsAttendance has to override Equals or implement IEquatable<clsAttendance>. Otherwise it's only found if it's the same reference. Always override also GethashCode.

此示例同时显示了推荐的两种方法:

This example shows both which is recommended anyway:

public class clsAttendance : IEquatable<clsAttendance>
{
    public string TagId { get; set; }
    public DateTime LastFoundDate { get; set; }
    public DateTime CapturedAt { get; set; }

    public override bool Equals(object obj)
    {
        var otherAttendance = obj as clsAttendance;
        if (otherAttendance == null)
        {
            return false;
        }

        return this.Equals(otherAttendance);
    }

    public override int GetHashCode()
    {
        return (this.TagId != null ? this.TagId.GetHashCode() : 0);
    }

    public bool Equals(clsAttendance other)
    {
        if (ReferenceEquals(null, other)) return false;
        if (ReferenceEquals(this, other)) return true;
        return string.Equals(this.TagId, other.TagId);
    }
}

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