Question

I have an ASP.net MVC controller action that is retrieving a list of items from my entity model. For this entity, there are a few properties that aren’t in the entity itself. I created a partial class to add these properties:

public partial class Person
{
    public int Extra
    {
        get
        {
            using( var ctx = new DBEntities() )
            {
                return ctx.OtherTable.Count(p => p.PersonID == this.PersonID);
            }
        }
    }
}

As you can see, the property that I need access to comes from another table. In my MVC page…I need to return a large number of people (100+ per page). In order to display this Extra field, each Person entity is going to be hitting the database separately…which has been extremely inefficient. I have one query to return all the people, and then for each person it has a query for each property I have like this. This can end up being 300 calls to the database, which is taking a long time to execute.

What is a better way to do this? I would ideally like to execute one query that returns all the People and the extra data, but I would also like the extra data to be part of the Person entity, even if it is in a separate table in the database.

Update
To add a little more context from the comments.

I am returning the People from a repository class. I was told in another question that the repository should only be dealing with the entities themselves. So the code that retrieves the people is like:

class PersonRepository
{
    public IQueryable<Person> GetPeople() {
        return from p in db.People
               where p ...
               select p;
    }
}

I don’t really have the option to join in that case.

Answer 1

You could do joins:

var result = 
    from p in ctx.Persons
    from a in ctx.OtherTable
    where p.PersonID == personID
    select new SomeViewModel 
    {
        Name = p.Person.Name,
        OtherTableValue = a.OtherValue
    };