CODEWITHSUNDEEP
entity-frameworkef-code-firstef-fluent-api
tgrabus
tgrabus

Reputation: 113

How to configure one to one relation using only fluent api without conventions

Is it possible to configure one to one relationship using fluent api on database which does not meet convention requirements? Below I give you sample of database and generated models. Be aware of that tables do not define any constraints and indices except primary keys.

Tables:

create table Person (
   PersonKey int primary key
)

create table Address (
   AddressKey int primary key,
   owner int not null // normally should be foreign key to Person
)

Code first models generated from db:

public partial class Person
{
    [Key]
    [DatabaseGenerated(DatabaseGeneratedOption.None)]
    public int PersonKey { get; set; }
}

public partial class Address
{
    [Key]
    [DatabaseGenerated(DatabaseGeneratedOption.None)]
    public int AddressKey { get; set; }

    public int Owner { get; set; }
}

To be able to navigate from Address to Person, navigation property was added to Address class:

public partial class Address
{
    [Key]
    [DatabaseGenerated(DatabaseGeneratedOption.None)]
    public int AddressKey { get; set; }

    public int Owner { get; set; }

    public virtual Person Person { get; set; }
}

If program tries execute this query:

var Addresss = context.Addresss.Include(x => x.Person).ToList();

runtime raises exception: "Invalid column name 'Person_PersonKey'". Because context do not configure any custom mappings it tries to find foreign key by convention but Owner property does not meet convention requirements, hence the exception. So there is a need to add mappings. If relationship between Person and Address would be one to many we could add such a configuration:

modelBuilder.Entity<Address>()
            .HasOptional(x => x.Person)
            .WithMany()
            .HasForeignKey(x => x.Owner);

and query defined above would execute correctly. But what if Person class would have navigation property to Address so we would have bidirectional one to one relation:

public partial class Person
{
    [Key]
    [DatabaseGenerated(DatabaseGeneratedOption.None)]
    public int PersonKey { get; set; }

    public virtual Address Address { get; set; }
}

So above configuration will not work and my question is, is it possible to configure it without changing db and property names and if yes what configuration needs to be applied using only fluent api?

Upvotes: 1

Views: 433

Answers (1)

renakre
renakre

Reputation: 8291

Here is my suggested code, I hope I understand you correctly!

public partial class Person
{
    public int PersonKey { get; set; }

    public Address Address {get;set;}
}

public partial class Address
{
    public virtual Person Person { get; set; }

    public int PersonId { get; set; }

    public string AddressInfo {get;set;}
}

 modelBuilder.Entity<Person>() 
             .HasKey(a => a.PersonKey); 

 modelBuilder.Entity<Course>()
             .Property(c => c.CourseId)
             .HasDatabaseGeneratedOption(DatabaseGeneratedOption.None);

 modelBuilder.Entity<Address>() 
             .HasKey(a => a.PersonId); 

 modelBuilder.Entity<Person>() 
             .HasRequired(p => p.Address) 
             .WithRequiredPrincipal(a => a.PersonId);

Upvotes: 1

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