C# LINQ使用Distinct方法检查对象某个属性的值是否重复

  C# LINQ使用Distinct方法检查对象某个属性的值是否重复

方案一：采用GroupBy方式, Count()>1为重复对象

C# Code:

List<tb_TablesDetail> list = gcStuct.DataSource as List<tb_TablesDetail>;

var query = list.GroupBy(x => x.FieldName.ToUpper())//区分大小写，转换为大写
.Where(g => g.Count() > 1)
.Select(y => y.Key)
.ToList();

if (query.Count>0)
{
  var strFields = String.Join(",", query.ToArray());//连接重复的字段
   Msg.Warning($"字段名<{strFields}>重复，请检查！");
  return;
}


//来源:C/S框架网 | www.csframework.com | QQ:23404761

方案二：采用Distinct方式，然后比较对象数量是否一致

C# Code:

List<tb_TablesDetail> list = gcStuct.DataSource as List<tb_TablesDetail>;
var fields = list.Select(a => a.FieldName).Distinct();
if (fields.Count() != list.Count)
{
  Msg.Warning("字段名称重复，请检查！");
  return;
}

//来源:C/S框架网 | www.csframework.com | QQ:23404761

方案三：采用Distinct方法，自定义比较对象的模型与算法

C# Code:

//LINQ使用Distinct方法检查对象某个属性的值是否重复
var q = list.Distinct(new DataCompareModel());
if (q.Count() < list.Count)
{
  string msg = "{\"status\":0, \"msg\":\"字段名称有重复，请检查！\"}";
  context.Response.Write(msg);
  return;
}

//来源:C/S框架网 | www.csframework.com | QQ:23404761

C# Code:

/// <summary>
/// 对象比较
/// </summary>
public class DataCompareModel : IEqualityComparer<libs.ExcelDataModel>
{
  public bool Equals(libs.ExcelDataModel x, libs.ExcelDataModel y)
  {
    return x.FieldName.CompareTo(y.FieldName) == 0;
  }
  
  public int GetHashCode(libs.ExcelDataModel obj)
  {
    return this.GetHashCode();
  }
}

//来源:C/S框架网 | www.csframework.com | QQ:23404761

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