C#•7mo ago

✅ Fluent API Relationship Help

Hey there, I am trying to write out the relationship between the Route and OrderRoute table as shown in the picture, but I am lost on actually how to do it. This is my first time working with EF in general. Any advice would be appreciated. What I have so far:

            modelBuilder.Entity<Route>(entity =>
            {
                entity.HasKey(e => e.RouteId); // PK
                entity.Property(e => e.RouteId).ValueGeneratedOnAdd(); // AUTO_INCREMENT
                entity.Property(e => e.Destination).HasMaxLength(50); // MAX 50 CHARS
                entity.Property(e => e.Destination).IsRequired(); // NOT NULL
                entity.Property(e => e.Km).IsRequired(); // NOT NULL
                entity.Property(e => e.Time).IsRequired(); // NOT NULL
                entity.Property(e => e.West).HasMaxLength(50); // MAX 50 CHARS
                entity.Property(e => e.West).IsRequired(); // NOT NULL
                entity.Property(e => e.East).HasMaxLength(50); // MAX 50 CHARS
                entity.Property(e => e.East).IsRequired(); // NOT NULL

                // Relationship to OrderRoute
                entity.HasOne<OrderRoute>();
            });

            modelBuilder.Entity<OrderRoute>(entity =>
            {
                entity.HasKey(e => e.OrderRouteId);
                entity.Property(e => e.OrderRouteId).ValueGeneratedOnAdd();
                entity.Property(e => e.RouteId).IsRequired();
                entity.Property(e => e.ContractId).IsRequired();

                // Relationship to Route
                entity.HasMany<Route>();
            });

            modelBuilder.Entity<Route>(entity =>
            {
                entity.HasKey(e => e.RouteId); // PK
                entity.Property(e => e.RouteId).ValueGeneratedOnAdd(); // AUTO_INCREMENT
                entity.Property(e => e.Destination).HasMaxLength(50); // MAX 50 CHARS
                entity.Property(e => e.Destination).IsRequired(); // NOT NULL
                entity.Property(e => e.Km).IsRequired(); // NOT NULL
                entity.Property(e => e.Time).IsRequired(); // NOT NULL
                entity.Property(e => e.West).HasMaxLength(50); // MAX 50 CHARS
                entity.Property(e => e.West).IsRequired(); // NOT NULL
                entity.Property(e => e.East).HasMaxLength(50); // MAX 50 CHARS
                entity.Property(e => e.East).IsRequired(); // NOT NULL

                // Relationship to OrderRoute
                entity.HasOne<OrderRoute>();
            });

            modelBuilder.Entity<OrderRoute>(entity =>
            {
                entity.HasKey(e => e.OrderRouteId);
                entity.Property(e => e.OrderRouteId).ValueGeneratedOnAdd();
                entity.Property(e => e.RouteId).IsRequired();
                entity.Property(e => e.ContractId).IsRequired();

                // Relationship to Route
                entity.HasMany<Route>();
            });

Thanks

16 Replies

Angius•7mo ago

You only really need to configure one side of the relationship

class Foo
{
    public int Id { get; set; }
    public int BarId { get; set; } // optional
    public Bar Bar { get; set; }
}
class Bar
{
    public int Id { get; set; }
    public List<Foo> Foos { get; set; }
}

class Foo
{
    public int Id { get; set; }
    public int BarId { get; set; } // optional
    public Bar Bar { get; set; }
}
class Bar
{
    public int Id { get; set; }
    public List<Foo> Foos { get; set; }
}

builder.Entity<Foo>(entity => {
  entity.HasOne(f => f.Bar)
        .WithMany(b => b.Foos);
});

builder.Entity<Foo>(entity => {
  entity.HasOne(f => f.Bar)
        .WithMany(b => b.Foos);
});

Jimmacle•7mo ago

yeah you can get rid of most of that configuration if you follow EF conventions

Angius•7mo ago

Like non-nullable properties automatically being required

MaybeJon•7mo ago

Do you mean attributes in the class themselves instead of using the modelBuilder? Thank you!

Jimmacle•7mo ago

no, i mean nothing at all EF can determine things like primary keys, navigations, required or not, etc just by how you define the properties

MaybeJon•7mo ago

Oh.. I didn't know that

Jimmacle•7mo ago

for example https://learn.microsoft.com/en-us/ef/core/modeling/relationships/conventions

Conventions for relationship discovery - EF Core

How navigations, foreign keys, and other aspects of relationships are discovered by EF Core model building conventions

Jimmacle•7mo ago

i only use the fluent API to configure things that can't be detected by convention

Angius•7mo ago

For example

class Foo
{
    // It's named `Id` so it's the primary key
    public int Id { get; set; }
    // The name `BarId` means it's the foreign key to `Bar`
    // Neither this nor `Bar` are nullable, so neither will be
    // the foreign key in the database
    public int BarId { get; set; }
    // And this sets the relationship to `Bar`
    public Bar Bar { get; set; }
}

class Foo
{
    // It's named `Id` so it's the primary key
    public int Id { get; set; }
    // The name `BarId` means it's the foreign key to `Bar`
    // Neither this nor `Bar` are nullable, so neither will be
    // the foreign key in the database
    public int BarId { get; set; }
    // And this sets the relationship to `Bar`
    public Bar Bar { get; set; }
}

MaybeJon•7mo ago

That's neat but looks very confusing to me tbh. We're required to write it all out for this group project, so it's easier for all my team members to understand Gotcha that's actually such a great feature Thanks a bunch

Jimmacle•7mo ago

school and teaching a less optimal way to do things name a better duo

MaybeJon•7mo ago

Lol yup.. still teaching .NET Framework

Jimmacle•7mo ago

you shouldn't mix annotations and fluent imo between that and EF conventions your model is like triple redundant lul

MaybeJon•7mo ago

Fair But relationship wise with the image I provided, would that be accurate?

Jimmacle•7mo ago

i don't think that's how you're supposed to use the ForeignKey attribute but if you're using some old EF version maybe it is, i've only used Core

MaybeJon•7mo ago

Gotcha, thanks a bunch

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✅ Fluent API Relationship Help