从EntitySet中拉出逗号分隔的字符串<T>

Question

How do I convert EntitySet<> to a String? ie (bob, joe, frank)?

In the below LINQ ContactType is a seperate table that can have numerous values. I am trying to convert it into a comma seperated string.

var caseNotes =context.tblCaseNotes
                .Where(cn => cn.PersonID == personID)
                .OrderBy(cn => cn.ContactDate)
                .Select(cn => new
                            {
                                cn.ContactDate,
                                cn.ContactDetails,
                                cn.TimeSpentUnits,
                                cn.IsCaseLog,
                                cn.IsPreEnrollment,
                                cn.PresentAtContact,
                                ContactType = string.Join(", ", cn.tblCaseNoteContactTypes.ToArray()),
                                cn.InsertDate,
                                cn.InsertUser,
                                cn.CaseNoteID,
                                cn.ParentNote
                            });

Answer 1

You have to select which column from tblCaseNoteContactTypes you want to concat

 ContactType = string.Join(", ", 
         cn.tblCaseNoteContactTypes.Select(x => x.MyColumn))

Answer 2

Append .ToArray(); at the end of your LINQ query, and use it as parameter for String.Join()

String.Join(", ", yourLinqQuery.ToArray());

For this to work, your LINQ query must return a string, so that the Array is a array of string. Or an object who has a ToString() that matches what you want.

String.Join(string, object[])

EDIT: as you added new info:

If tblCaseNotesContactTypes is an object, you need to add a .Select(t -> {return t converted to string}) before the .ToArray()

Answer 3

Check for empty?

ContactType = cn.tblCaseNoteContactTypes.Any() ? string.Join(", ", cn.tblCaseNoteContactTypes.ToArray()) : String.Empty

Also,

tblCaseNoteContactTypes

If the members of this collection aren't strings, Join is going to have some trouble.