Populating a DTO with a property list of DTO by using transform

Question

I have a entity called ActivityLog:

    public class ActivityLog : EntityModel<ActivityLog>
{
    public virtual int activityID { get; set; }
    public virtual int entityType { get; set; }
    public virtual int entityID { get; set; }
    public virtual string entityName { get; set; }
    public virtual int action { get; set; }
    public virtual int parentType { get; set; }
    public virtual int parentID { get; set; }
    public virtual string parentName { get; set; } }
    public virtual string userName { get; set; }
    public virtual int instanceID { get; set; }
    public virtual DateTime? timeStamp { get; set; }
    public virtual DateTime? groupTimeStamp { get; set; }
}

and a DTO class called Activity:

    public class Activity
{
    public virtual int activityID { get; set; }
    public virtual int entityType { get; set; }
    public virtual int entityID { get; set; }
    public virtual string entityName { get; set; }
    public virtual int action { get; set; }
    public virtual int parentType { get; set; }
    public virtual int parentID { get; set; }
    public virtual string parentName { get; set; }
    public virtual string userName { get; set; }
    public virtual int instanceID { get; set; }
    public virtual DateTime? timeStamp { get; set; }
    public virtual DateTime? groupTimeStamp { get; set; }
    public IList<Activity> activities { get; set; }
}

I need to fill DTO from Entity with transform also I want to fill IList<Activity> with the entities which have parentType and parentID. What is the best way to do it, with minimum query?

Answer 1

IList<ActivityLog> activityLogs = ...;

var activities = session.Query<Activity>()
    .WhereRestrictionOn(a => a.Parent.Id).IsIn(activityLogs.Select(al => al.parentID))
    .WhereRestrictionOn(a => a.Parent.Type).IsIn(activityLogs.Select(al => al.parentType))
    .AsEnumerable()
    .ToLookUp(a => new { ParentId = a.Parent.Id, ParentType = a.Parent.Type });

var results = activityLogs
    .Select(al => new ActivityDTO
    {
        activityID = al.activityID,
        entityType = al.entityType,
        ...
        activities = activities[new { ParentId = al.parentID, ParentType = al.parentType }].ToList()
    });