How to have intermediate table for a 1 to many relationship? - entity-framework

Question

I have a model class:
public class UserProfile
{
public string UserID { get; set; }
public string Name{ get; set; }
public ICollection<AddressMaster> AddressMaster { get; set; }
}
The above class have a 1 to many relationship with AddressMaster model class given below:
public class AddressMaster
{
public string AddrID{ get; set; }
public string AddressLine1{ get; set; }
public UserProfile UserProfile { get; set; }
public TheatreLocation TheatreLocation { get; set; }
}
The problem is, there is one other model also that has a 1 to many relationship with addressmaster, which is:
public class TheatreLocation
{
public string LocationID { get; set; }
public string Name{ get; set; }
public ICollection<AddressMaster> AddressMaster { get; set; }
}
So instead of having foreign key at the addressmaster, how can we have a intermediate table between addressmaster and the userprofile & another such table b/w addressmaster and theatre?
Or am i getting the whole concept wrong?
Thanks.

Answer 1

So instead of having foreign key at the addressmaster, how can we have
a intermediate table between addressmaster and the userprofile &
another such table b/w addressmaster and theatre?
If you do not want to set any foreign key and add a intermediate table.Design like below:
public class UserProfile
{
[Key]
public string UserID { get; set; }
public string Name { get; set; }
}
public class AddressMaster
{
[Key]
public string AddrID { get; set; }
public string AddressLine1 { get; set; }
}
public class UserAddress
{
[Key]
public string AddrID { get; set; }
public string UserID { get; set; }
}
Add the primary key to the intermediate table UserAddress.The AddrId could only has one value,but the UserID could have many value which is like one-to-many relationship.
Or am i getting the whole concept wrong?
Nothing wrong.Using navigation property like what you did is also good.

Answer 2

Your table definitions would probably wind up something like this:
UserProfile
UserId PK
Theather
TheatreId PK
Address
AddrID PK
AddressLine1
UserAddress
UserId PK & FK
AddressId FK
TheatreAddress
TheatreID PK & FK
AddressId FK
This is just good normalisation - i.e. you have a generic 'address' table in the database. Several entities may have an address and have either one-many or many-many relationships with addresses, but a specific address only needs to be recorded once.
The PK on the intermediate table only on the UserId (for example) ensures that this is one-many and not many-many.