LINQ - How to concatenate two fields in a Group By?-CodePudding

I have a ReportStatusEntity class as shown below:

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

Let's say I have the following list of List<ReportStatusEntity>():

{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}

I want to group by PolicyNumber, then concatenate the ClientNames having same PolicyNumber with '&'.

The grouping should be something like this:

{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)}

How can this be done in C# using LINQ? Thank you.

CodePudding user response：

var list = new List<ReportsStatusEntity>()
{
    new ReportsStatusEntity{PolicyNumber = "1", ClientName = "John Doe", HasIndividualBrokers = true},
    new ReportsStatusEntity{PolicyNumber = "1", ClientName = "Sarah Doe", HasIndividualBrokers = true},
    new ReportsStatusEntity{PolicyNumber = "2", ClientName = "Paul Smith", HasIndividualBrokers = false},
    new ReportsStatusEntity{PolicyNumber = "3", ClientName = "Ryan Johnson", HasIndividualBrokers = false}
};

var results = list.GroupBy(r => r.PolicyNumber)
    .Select(g => new
    {
        PolicyNumber = g.Key,
        // string.Join will not work if its against a database with sql
        ClientNames = string.Join(" & ", g.Select(r => r.ClientName)),
    });

foreach (var result in results)
{
    Console.WriteLine($"Policy {result.PolicyNumber}: {result.ClientNames}");
}

// -- Outputs --
// Policy 1: John Doe & Sarah Doe
// Policy 2: Paul Smith
// Policy 3: Ryan Johnson

CodePudding user response：

You can first group all ReportStatusEntity by PolicyNumber

List<List<ReportStatusEntity>> listReportStatusEntityGroupped = this.yourList.GroupBy(u => new { u.PolicyNumber,u.HasIndividualBrokers })
                                                .Select(grp => grp.ToList())
                                                .ToList();

The new { u.PolicyNumber } is not obligatory as you group only on one parameter, but you then can add others.

Then, once you have your List<List<ReportStatusEntity>>, you can make a foreach :

List<ReportStatusEntity> outputList=new List<ReportStatusEntity>();
foreach(List<ReportStatusEntity> listReportInGroup in listReportStatusEntityGroupped)
{
    ReportStatusEntity newReport = new ReportStatusEntity
    {
        PolicyNumber=listReportInGroup[0].PolicyNumber,
        HasIndividualBrokers = listReportInGroup[0].HasIndividualBrokers,
        ClientName = string.Join(" & ",listRepInGroup.Select(x=>x.ClientName)),
    };
    outputList.Add(newReport);
}

CodePudding user response：

1- Create a class as below:

public class ReportsStatusLastEntity
{
  public int Id { get; set; }
  public string PolicyNumber { get; set; }
  public string ClientName { get; set; }
  public bool HasIndividualBrokers { get; set; }
}

2- Create List <ReportsStatusLastEntity> liste= new List<ReportsStatusLastEntity>()

3- Start foreach loop by list ReportStatusEntity

4- Check PolicyNumber on ReportsStatusLastEntity Id. If true add name. Else add new item.