Can I set my PrimaryKey to Model before adding it into the Table (_db.Table.Add(Model);)?

Question

Hi!

I have a Table_A table, it has a unique Primary Key. The model that writes there, for example, is: Model {Id (Primary Key), a, b, c, d}. I need to keep a copies of Models (from Table_A) somewhere (in an independent Table_B table), but so that this copy is created (updated) when I need it, AND HAS the SAME Id(Primary Key). Is it possible to implement this in net.core or maybe there is another way? How do I create a Table_B table -with Id(Primary Key) or just with Id (to specify Id manually when recording)? Most importantly, I need to use the same Model in operations with tables Table_a and Table_B.

Is it possible to implement this and how? Or are there more elegant ways?

P.S. Here, for example, they write that it is impossible to create a table without PrimaryKey at all.
Can we have table without primary key in entity framework?
https://stackoverflow.com/questions/15381233/can-we-have-table-without-primary-key-in-entity-framework
Then how do I set manually PrimaryKey to Table_B, which stores the same Model?

Maybe, is it possible to link Primary Key in two tables Table_B with Table_A so that they match when creating a record in Table_B? I just don't want to create a separate model (extend Model), and then when writing to Table_B, copy all the properties from Model to NewModel (clone). Or is there a Clone() command for such a case?

Thanks!

Answer 1

Hi,@Volk Volk

Accroding to your description

is it possible to link Primary Key in two tables Table_B with Table_A so that they match when creating a record in Table_B? I just don't want to create a separate model (extend Model), and then when writing to Table_B, copy all the properties from Model to NewModel (clone).

you may try with Table splitting

Create an Entity:

public class MyEntity
    {
        public int Id { get; set; }

        public string? Prop1 { 
            get { return Prop1Copy; } 
            set { Prop1Copy = value; }
        }

        public string? Prop1Copy { get ; private set; }
        // In my case,Prop1Copy would share the same value with Prop1,when you create/delete a record 
        //in MyEntity table,the record in MyEntityTableCopy table would also be created/deleted
        // you could modify the getter/setter here and create a method to clone the properties
    }

Configure as below in dbcontext:

protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
        modelBuilder.Entity<MyEntity>
            (
               eb =>
               {
                   eb                     
                     .ToTable("MyEntity",
                      tablebuilder=> {
                          tablebuilder.Property(x=>x.Id).HasColumnName("Id");
                          tablebuilder.Property(x => x.Prop1).HasColumnName("Prop1");
                          })
                     .SplitToTable("MyEntityTableCopy",
                      tablebuilder => {
                          tablebuilder.Property(x => x.Id).HasColumnName("Id");
                          tablebuilder.Property(x => x.Prop1Copy).HasColumnName("Prop1Copy");
                      });
               }
            );
    }

Result

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