RDLC: show child collection data without using subreports

I encountered a similar problem. I had a report running of a list of CustomObject. The CustomObject list was populated from a query on a list of ParentObjects that contained many-many references to all their CustomObjects. The relationship was removed and a string column was used on the ParentObject (ParentObject.CustomObjectName) instead. Now my report receives a string[] containing all the CustomObject names.

My solution was creating a wrapper object with a single string property and a constructor to use as my data source. I named it just like the CustomObject my report was expecting.

class CustomObject 
{ 
   public string Name {get; set;} 

   public CustomObject(string name)
   {
      Name = name;
   }
}

I load my list using LINQ, I call the wrapper constructor in the select statement

var wrappedObjects = from parent in GetParentObjects()
   select new CustomObject(parent.CustomObjectName);

From the report you can add a data source for the CustomObject class like you normally would and access the object as usual "=Fields!Name.Value".

I have loaded Reporting Service reports from business objects before (loaded via NHibernate -- which isn't exact but close enough for argument sake).

Couple of key points: 1. return your objects in List, even if you are only returning one object. 2. You want FLAT business objects. You might have to go thru a DTO transformation to get that. By flat, I mean the most complex property you can have in a business object is a string and a number (int, decimal, double). If you are expecting to grab a value like this: myObject.Customer.Name, forget it. Create a CustomerName property. 3. If you need data from multiple places try to break up your reports into subreports. You key off of the datasource key to figure out what data to return to the report.

I'll add more as I remember, it has been a few months since I've done this.