LINQ分组拼接字段：按PolicyNumber分组并拼接ClientName

问题背景 #

现有如下定义的ReportsStatusEntity类：

public class ReportsStatusEntity
{
    public string PolicyNumber { get; set; }
    public string ClientName { get; set; }
    public bool HasIndividualBrokers { get; set; }
}

以及一个List<ReportsStatusEntity>类型的数据集：

{PolicyNumber = 1, ClientName = "John Doe", HasIndividualBrokers = True},
{PolicyNumber = 1, ClientName = "Sarah Doe", HasIndividualBrokers = True},
{PolicyNumber = 2, ClientName = "Paul Smith", HasIndividualBrokers = False},
{PolicyNumber = 3, ClientName = "Ryan Johnson", HasIndividualBrokers = False}

需求是按PolicyNumber分组，将同组的ClientName用&拼接，得到如下结果：

{PolicyNumber = 1, ReportStatusEntity = (PolicyNumber = 1, ClientName = "John Doe & Sarah Doe", HasIndividualBrokers = True)},
{PolicyNumber = 2, ReportStatusEntity = (PolicyNumber = 2, ClientName = "Paul Smith", HasIndividualBrokers = False)},
{PolicyNumber = 3, ReportStatusEntity = (PolicyNumber = 3, ClientName = "Ryan Johnson", HasIndividualBrokers = False)}

实现代码 #

可以通过LINQ的GroupBy分组后，结合String.Join拼接客户端名称，再构造目标结构：

// 假设reportList是你的List<ReportsStatusEntity>数据源
var groupedResult = reportList
    .GroupBy(entity => entity.PolicyNumber)
    .Select(group => new 
    {
        PolicyNumber = group.Key,
        ReportStatusEntity = new ReportsStatusEntity
        {
            PolicyNumber = group.Key,
            ClientName = string.Join(" & ", group.Select(e => e.ClientName)),
            // 同组内HasIndividualBrokers值一致，取第一个实体的属性值
            HasIndividualBrokers = group.First().HasIndividualBrokers
        }
    })
    .ToList();

代码说明 #

• 分组：GroupBy(entity => entity.PolicyNumber)按保单编号对实体分组，每个分组的Key对应唯一的PolicyNumber。
• 拼接名称：string.Join(" & ", group.Select(e => e.ClientName))提取分组内所有客户端名称，用&连接成单个字符串。
• 处理布尔属性：假设同一保单编号下的HasIndividualBrokers值完全一致，直接取分组内第一个实体的属性值；如果业务中存在同组值不同的情况，需要根据需求调整（比如取逻辑与、逻辑或，或者抛出异常）。

内容的提问来源于stack exchange，提问作者1fuyouinfinite