User306743125 posted
Hi
Using EF Core 5, which allows for many-to-many relationships. EF 5 basically creates the join tables for you.
public class Buyer
{
public int Id {get;set;
public string BuyerName {get;set;}
public ICollection<Supplier>Suppliers {get;set;}
}
public class Supplier
{
public int Id {get;set;}
public string SupplierName {get;set;}
public ICollection<Buyer>Buyers {get;set;}
}
public class Invoice
{
public int Id {get;set;}
public string InvoiceNumber {get;set;}
public decimal InvoiceAmount {get;set;}
public ICollection<BuyerSupplier>BuyerSupplier {get;set;}
}
I have 3 entities: Buyer, Supplier and Invoice.
Buyers and Suppliers have a many-to-many relationship.
Each Invoice will have 1 Buyer and 1 Supplier...But only if the selected Buyer and Supplier is related.
It is easy enough to have a cascading dropdown on the Invoice Create View to only display Buyer of the selected Supplier, thus forcing the user to select a Buyer which is related to a Supplier.
For example: Supplier 1 delivers to Buyer 1 and 2
But Supplier 2 only delivers to Buyer 1
An Invoice with Buyer 2 selected should not allow a Supplier of 2
But I am worried that, that there is no FK in the database to enforce the requirement. If, for example, I import Invoices from file nothing will force the given Suppliers and Buyers to be related.
I was thinking that the Invoice entity should not be related to the Buyer and Supplier entities, but should rather be related to BuyerSupplier entity (the Join table of the many-to-many relationship). But that seems to bring a whole lot of other complications.
Anyone advice?
