Linq多次选择查询与Distinct

Question

I have the following models:

public class Person
{
    public string fullName { get; set; }
    public virtual ICollection<Hobby> hobbies { get; set; }
    public virtual Location location { get; set; }
}

public class Hobby
{
    public string hobbyName { get; set; }
    public virtual ICollection<Person> people { get; set; }           
}

public class Location
{
   public string locationName { get; set; }
   public virtual ICollection<Person> People { get; set; }
}

A Person can have many hobbies, and vice Versa, and a Person can have a single Location.

I'd like to do a query that for a given Location returns all the distinct Hobbies from the people in that Location

So if the location is "Dallas", find all the people in Dallas, return all their Hobbies, and remove the duplicates.

Answer 1

You can try this way :

var hobbies = (from h in hobbies
                where h.people.Any(p => p.location.locationName == "Dallas")
                select h);

Answer 2

you have the relationship well represented using FKs, so you can simplify your query like this:

from p in persons 
Where p.location.locationName = "London"
select new 
{
    person = p,
    hobbies = p.hobbies
}