Asp.net mvc4 how to join entities by using linq - asp.net

Question

I have a problem with joining two entities by linq language.
I have model Category:
public class Category : DbContext
{
[Key, Column(Order = 0),DatabaseGenerated(DatabaseGeneratedOption.Identity)]
public int CategoryId { get; set; }
Key, Column(Order = 1)]
public int ShopId { get; set; }
public string Name {get;set;}
public virtual ICollection<Parameter> Parameter { get; set; }
}
and model Parametr
public class Parameter : DbContext
{
[Key, Column(Order = 0),DatabaseGenerated(DatabaseGeneratedOption.Identity)]
public int ParamId { get; set;}
[Key, Column(Order = 1)]
public int ShopId { get; set;}
public string Name {get; set;}
public string Value {get;set;}
}
The relation is one to many, so one Category coud have 0...n Parameters.
UPDATE:
Sure, the relationship is many to many. This is the reason, why Parameter has no CategoryId attribute in the model.
I'm using code first and migration tool for updataing database;
In database MSSQL Express are 3tables. Category, CategoryParameters and Parameters.
Table CategoryParameter was created automaticaly and I have no Model for this table.
Creating new Category with multiple Parameters working fine. All 3tables contains valid data.
So my problem now:
I'm trying to load all parameters for one Category. The command looks like:
var parameters = from c in db.Categories
join p in db.Parameters
on new { ??? , c.ShopId } equals new { ??? , p.ShopId }
where c.ShopId == userProfile.ShopId && c.CategoryId == id
select new { ParamId = p.ParamId, Name = p.Name };
So my problem is, how to hell join these tables, if there is no usable atribute in the classes.
Many thanks for any help!

Answer 1

You don't need JOIN: use navigation property instead:
Find the category entity.
Use Parameter property of the category entity.
var parameters = db.Categories.First(x => x.CategoryId == 10).Parameter.ToList();