Budgeteer/BudgetApp/Data/ApplicationDbContext.cs

using Microsoft.AspNetCore.Identity.EntityFrameworkCore;
using Microsoft.EntityFrameworkCore;

namespace BudgetApp.Data;

public class ApplicationDbContext : IdentityDbContext<ApplicationUser>
{
    public ApplicationDbContext(DbContextOptions<ApplicationDbContext> options)
        : base(options)
    {
    }

    public DbSet<Account> Accounts => Set<Account>();
    public DbSet<Transaction> Transactions => Set<Transaction>();
    public DbSet<Category> Categories => Set<Category>();
    public DbSet<Salary> Salaries => Set<Salary>();

    protected override void OnModelCreating(ModelBuilder builder)
    {
        base.OnModelCreating(builder);

        builder.Entity<Account>(e =>
        {
            e.HasOne(a => a.User)
             .WithMany()
             .HasForeignKey(a => a.UserId)
             .OnDelete(DeleteBehavior.Cascade);

            e.Property(a => a.CurrentBalance).HasColumnType("decimal(18,2)");
        });

        builder.Entity<Transaction>(e =>
        {
            e.HasOne(t => t.Account)
             .WithMany(a => a.Transactions)
             .HasForeignKey(t => t.AccountId)
             .OnDelete(DeleteBehavior.Cascade);

            e.HasOne(t => t.Category)
             .WithMany(c => c.Transactions)
             .HasForeignKey(t => t.CategoryId)
             .OnDelete(DeleteBehavior.SetNull);

            e.HasOne(t => t.ParentTransaction)
             .WithMany()
             .HasForeignKey(t => t.ParentTransactionId)
             .OnDelete(DeleteBehavior.SetNull);

            e.HasOne(t => t.Salary)
             .WithMany()
             .HasForeignKey(t => t.SalaryId)
             .OnDelete(DeleteBehavior.SetNull);

            e.Property(t => t.Amount).HasColumnType("decimal(18,2)");
        });

        builder.Entity<Category>(e =>
        {
            e.HasOne(c => c.User)
             .WithMany()
             .HasForeignKey(c => c.UserId)
             .OnDelete(DeleteBehavior.Cascade);
        });

        builder.Entity<Salary>(e =>
        {
            e.HasOne(s => s.User)
             .WithMany()
             .HasForeignKey(s => s.UserId)
             .OnDelete(DeleteBehavior.Cascade);

            e.HasOne(s => s.Account)
             .WithMany()
             .HasForeignKey(s => s.AccountId)
             .OnDelete(DeleteBehavior.Cascade);

            e.Property(s => s.Amount).HasColumnType("decimal(18,2)");
        });
    }
}