Setting the On Update Cascade Constraint with Entity Framework Core

Question

There is a ton of info on setting the behavior for delete actions for foreign key relationships in Entity Framework Core, however, I have found nearly zero details on how to specify the "On Update Cascade" constraint of a foreign key.

The closest I have found is this migrations related Microsoft document.

public void Configure(EntityTypeBuilder<Something> builder)
{
    builder
        .HasOne(s => s.Thing)
        .WithMany(t => t.Somethings)
        .HasForeignKey(s => s.ThingId)
        --> Like Delete behavior, how to set update behavior?
        .OnDelete(DeleteBehavior.Cascade);
}

How can this be done with the Fluent API?

Answer 1

Update: This still does not fix the underlying issue of when you "context.SaveChanges();" it will still throw an error. You have to null the record in the Database and then repopulate it.

I have been looking for the Exact same thing and I found a work around. As far as I can tell you cannot do this in the Fluent API yet. What you can do is add it into the migration manually.

1. Add Migration
2. Open Migration
3. Find the "onDelete: ReferentialAction.Cascade);"
4. On the line above it, Insert "onUpdate: ReferentialAction.Cascade,"
5. Update and test database

6. See below for reference

           migrationBuilder.CreateTable(
           name: "AgencyMembers",
           columns: table => new
           {
               ApplicationUserId = table.Column<string>(maxLength: 450, nullable: false),
               AgencyId = table.Column<int>(nullable: false),
               AgencyName = table.Column<string>(nullable: true)
           },
           constraints: table =>
           {
               table.PrimaryKey("PK_AgencyMembers", x => new { x.ApplicationUserId, x.AgencyId });
               table.ForeignKey(
                   name: "FK_AgencyMembers_AspNetUsers_ApplicationUserId",
                   column: x => x.ApplicationUserId,
                   principalTable: "AspNetUsers",
                   principalColumn: "Id",
                   ***onUpdate: ReferentialAction.Cascade,***
                   onDelete: ReferentialAction.Cascade);
               table.ForeignKey(
                   name: "FK_AgencyMembers_Agencies_AgencyId_AgencyName",
                   columns: x => new { x.AgencyId, x.AgencyName },
                   principalTable: "Agencies",
                   principalColumns: new[] { "AgencyId", "AgencyName" },
                   ***onUpdate: ReferentialAction.Cascade,***
                   onDelete: ReferentialAction.Cascade);
           });