LINQ Distinct

private static List<MessageRecipientCandidate> GetRecipientListBoxDataSource(MessageRecipientCandidateCollection recipientCandidates, Int32 roleTypeId)
{
    var recipients = from recipient in recipientCandidates
                     where recipient.RoleTypeId == roleTypeId
                     group recipient by recipient.UserId into user
                     let userRec = user.First()
                     orderby userRec.LastName
                     select userRec;
 
    return recipients.ToList();
}

                                              

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private Guid userId = Constants.NullValue.NullGuid;
private String title = Constants.NullValue.NullString;
private String firstName = Constants.NullValue.NullString;
private String lastName = Constants.NullValue.NullString;
private String fullName = Constants.NullValue.NullString;
private Guid roleId = Constants.NullValue.NullGuid;
private String roleName = Constants.NullValue.NullString;
private Int32 roleTypeId = Constants.NullValue.NullInt;
private String roleTypeTitle = Constants.NullValue.NullString;
private String locationTitle = Constants.NullValue.NullString;
private Int32 locationId = Constants.NullValue.NullInt;
 
#endregion
 
#region Properties
 
public Guid UserId
{
    get { return userId; }
    set { userId = value; }
}
 
public String Title
{
    get { return title; }
    set { title = value; }
}
 
public String FirstName
{
    get { return firstName; }
    set { firstName = value; }
}
 
public String LastName
{
    get { return lastName; }
    set { lastName = value; }
}
 
public String FullName
{
    get { return fullName; }
    set { fullName = value; }
}
 
public Guid RoleId
{
    get { return roleId; }
    set { roleId = value; }
}
 
public String RoleName
{
    get { return roleName; }
    set { roleName = value; }
}
 
public Int32 RoleTypeId
{
    get { return roleTypeId; }
    set { roleTypeId = value; }
}
 
public String RoleTypeTitle
{
    get { return roleTypeTitle; }
    set { roleTypeTitle = value; }
}
 
public String LocationTitle
{
    get { return locationTitle; }
    set { locationTitle = value; }
}
 
public Int32 LocationId
{
    get { return locationId; }
    set { locationId = value; }
}
 
#endregion

                                              

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Then the function signature should look like this:
 
private static List<MessageRecipientCandidate> GetRecipientListBoxDataSource(List<MessageRecipientCandidate>
recipientCandidates, Int32 roleTypeId)
 
Then when you call the function it should be called like this:
 
List<MessageRecipientCandidate> employeeResults = GetRecipientListBoxDataSource(MessageRecipientCandidateCollection, roleTypeId);
                                              

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