ASP.NET Core : Fluent Api relationships configuration - asp.net-core

Question

There are a lot of examples how to use Fluent API in the internet, but mostly shows how configure one relationship between two models. In my case I need 3 relationships between 2 models. How to configure relationships between models below with Fluent API?
public class Company
{
public int Id { get; set; }
public string Name { get; set; }
public int FinanceEstimateId { get; set; }
public Estimate FinanceEstimate { get; set; }
public int EnvironmentEstimateId { get; set; }
public Estimate EnvironmentEstimate { get; set; }
public int SelfEstimateId { get; set; }
public Estimate SelfEstimate { get; set; }
}
public class Estimate
{
public int Id { get; set; }
public string Name { get; set; } // like: bad, good, excellent
public float Value { get; set; } // like: 1,2,3
}

Answer 1

Maybe this points you in the right direction.
I would go for 2 configurations like:
public class CompanyConfiguration : IEntityTypeConfiguration<Company>
{
public void Configure(EntityTypeBuilder<Company> builder)
{
builder.ToTable("Companies");
builder
.HasOne(x => x.EnvironmentEstimate)
.WithMany()
.HasForeignKey(x => x.EnvironmentEstimateId)
.OnDelete(DeleteBehavior.NoAction);
builder
.HasOne(x => x.FinanceEstimate)
.WithMany()
.HasForeignKey(x => x.FinanceEstimateId)
.OnDelete(DeleteBehavior.NoAction);
builder
.HasOne(x => x.SelfEstimate)
.WithMany()
.HasForeignKey(x => x.SelfEstimateId)
.OnDelete(DeleteBehavior.NoAction);
}
}
public class EstimateConfiguration : IEntityTypeConfiguration<Estimate>
{
public void Configure(EntityTypeBuilder<Estimate> builder)
{
builder.ToTable("Estimates");
}
}
You need a DbContext:
public class MyDbContext : DbContext
{
public DbSet<Company> Companies { get; set; } = null!;
protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
{
optionsBuilder.UseSqlServer(#"CONNECTIONSTRING");
}
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
base.OnModelCreating(modelBuilder);
// applies the configuration (those IEntityTypeConfiguration<T> things)
modelBuilder.ApplyConfigurationsFromAssembly(typeof(MyDbContext).Assembly);
}
}
I created a console application that demonstrates the usage
using var ctx = new MyDbContext();
await ctx.Database.EnsureDeletedAsync();
await ctx.Database.EnsureCreatedAsync();
var company1 = new Company
{
Name = "Name1",
EnvironmentEstimate = new Estimate { Name = "EnvironmentEstimate1", Value = 1 },
FinanceEstimate = new Estimate { Name = "FinanceEstimate1", Value = 2 },
SelfEstimate = new Estimate { Name = "SelfEstimate1", Value = 3 }
};
var company2 = new Company
{
Name = "Name2",
EnvironmentEstimate = new Estimate { Name = "EnvironmentEstimate2", Value = 4 },
FinanceEstimate = new Estimate { Name = "FinanceEstimate2", Value = 5 },
SelfEstimate = new Estimate { Name = "SelfEstimate2", Value = 6 }
};
await ctx.Companies.AddAsync(company1);
await ctx.Companies.AddAsync(company2);
await ctx.SaveChangesAsync();
var result = await ctx.Companies.ToListAsync();
Console.WriteLine("Done");