How can I make this LINQ query?

Question

I have a Dropdownlist that I fill with all consultants.

This is my entities I am using for this LINQ query:

What I want to do is to get all consultants ids that have a goalcard with Complete_date set. I have no idea how to do this.

Right now I have this following LINQ query to get all consultants ids.

public List<Consultant> GetAllConsultantsByID()
{
    var allConsultants = from id in db.Consultant
                         select id;
    return allConsultants.ToList();
}

Any kind of help is appreciated

Thanks in advance

Update:

This is how I have to use my Linq method in my Get Action Method:

var consultants = repository.GetAllConsultantsByID();
model.Consultants = new SelectList(consultants, "Id", "Name");

Answer 1

You can use the Consultant.GoalCard navigation property and the Any extension method:

var query = from con in db.Consultant
            where con.GoalCard.Any(card => card.Completed_Date != null)
            select con;
return query.ToList();

Consultant.Goalcard exposes all GoalCards of the Consultant as a queryable property. So you can perform queries on that, too. (This example assumes Completed_Date is nullable)

Note: Seeing that a Consultant can have several GoalCard s, you might want to rename the Consultant 's GoalCard navigation property to GoalCards (to make it clear there can be several).

Answer 2

Now assuming the Complete_Date is of type DateTime? , you could do it like that:

public IEnumerable<Consultant> GetConsultantIds()
{
     return db.Consultant.Where(c => c.GoalCard != null && c.GoalCard.Completed_Date.HasValue).Select(c => c.Id).AsEnumerable(); 
}

[EDIT]

Since GoalCard is a collection (misleading name :) ), you can do something like that to get the IDs of Consultants who have at least one completed date set on any of the cards:

public IEnumerable<int> GetConsultantIds()
{
     return db.Consultant.Where(c => c.GoalCard != null && c.GoalCard.Any(card => card.Completed_Date.HasValue)).Select(c => c.Id).AsEnumerable(); 
}

That's for the list of IDs only, for the list of Consultant objects meeting the criteria:

public IEnumerable<Consultant> GetConsultantIds()
{
     return db.Consultant.Where(c => c.GoalCard != null && c.GoalCard.Any(card => card.Completed_Date.HasValue)).AsEnumerable(); 
}