StockHistory/StockHistory/Data/AppDbContext.cs

using Microsoft.EntityFrameworkCore;
using StockHistory.Models;

namespace StockHistory.Data;

public class AppDbContext : DbContext
{
    public AppDbContext(DbContextOptions<AppDbContext> options)
     : base(options)
    {
    }

    public DbSet<TransactionNote> TransactionNotes { get; set; }
    public DbSet<StockEquity> Stocks { get; set; }

    override protected void OnModelCreating(ModelBuilder modelBuilder)
    {
        base.OnModelCreating(modelBuilder);
        modelBuilder.Entity<TransactionNote>()
        .HasIndex(t => new { t.StockCode, t.TransactionDate })
        .IsUnique(true);
        modelBuilder.Entity<StockEquity>()
            .HasIndex(s => new { s.Bought })
            .IsUnique(false);
        modelBuilder.Entity<StockEquity>()
            .HasIndex(s => new { s.Sold })
            .IsUnique(false);
    }
}