Code First Foreign Keys between two entities

1
votes

OK what am I missing here or is this just able to be done with data annotation?

I have a Document Entity Model which has a Foreign Key to a User that added the document (one-to-one relationship):

[Table("Documents", Schema = "Configuration")]
public class Document : IPrimaryKey {
    [Key]
    public long Id { get; set; }

    [Required]
    public string OrginalName { get; set; }

    [Required]
    public DocumentTypes DocumentType { get; set; }

    [Required]
    public MIMETypes MIMEType { get; set; }

    [Required]
    public byte[] Data { get; set; }

    [DefaultValue(false)]
    public bool IsPublic { get; set; }

    [Required]
    public DateTimeOffset DateTimeAdded { get; set; }

    [Required]
    public long AddedByUser { get; set; }

    [ForeignKey("AddedByUser")]
    public virtual Details Details { get; set; }
}

I then have a User (Details) Entity that can have an image file (which is stored in the document entities model (none|one-to-one relationship):

[Table("Details", Schema = "User")]
public class Details : IPrimaryKey {
    [Key]
    public long Id { get; set; }

    [Required]
    public string UserId { get; set; }

    [ForeignKey("UserId")]
    public AppUser User { get; set; }

    [Required]
    public string FirstName { get; set; }

    [Required]
    public string LastName { get; set; }

    [CollectionRequired(MinimumCollectionCount = 1)]
    public ICollection<Address> Addresses { get; set; }

    [CollectionRequired(MinimumCollectionCount = 1)]
    public ICollection<Email> Emails { get; set; }

    [CollectionRequired(MinimumCollectionCount = 1)]
    public ICollection<PhoneNumber> PhoneNumbers { get; set; }

    public ICollection<NotificationHistory> NotificationHistory { get; set; }
    public long TimeZoneId { get; set; }

    public long? ImageId { get; set; }

    [ForeignKey("ImageId")]
    public virtual Document Document { get; set; }

    [ForeignKey("TimeZoneId")]
    public virtual TimeZone TimeZone { get; set; }
}

When I try to create a Migration I get this error:

Unable to determine the principal end of an association between the types 'StACS.PeoplesVoice.DataAccessLayer.EntityModels.User.Details' and 'StACS.PeoplesVoice.DataAccessLayer.EntityModels.Configuration.Document'. The principal end of this association must be explicitly configured using either the relationship fluent API or data annotations.

UPDATED:

While still researching this I made two changes and was able to get around the error but this created an unexpected result in my database.

In the Document Entity I added:

public virtual ICollection<Details> Details { get; set; }

In the Details (user) Entity I added:

puflic virtual ICollection<Document> Documents { get; set; }

In my DB Tables I now have the foreign key on the field I want but I have a secondary foreign key for each respectively.

I tried just removing the single virtual reference and left ONLY the ICollection Virtual reference, now I have no foreign key at all.

UPDATED (based on Akash Kava Suggestion):

I have made the following changes [Table("Documents", Schema = "Configuration")] public class Document : IPrimaryKey { [Required] public string OrginalName { get; set; }

    [Required]
    public DocumentTypes DocumentType { get; set; }

    [Required]
    public MIMETypes MIMEType { get; set; }

    [Required]
    public byte[] DocumentData { get; set; }

    [DefaultValue(false)]
    public bool IsPublic { get; set; }

    [Required]
    public DateTimeOffset DateTimeAdded { get; set; }

    [Required]
    public long AddedByUser { get; set; }

    [Key]
    public long Id { get; set; }

    [ForeignKey("AddedByUser")]

    [InverseProperty("Image")]

    public virtual Details User { get; set; }
}

[Table("Details", Schema = "User")]
public class Details : IPrimaryKey {
    [Required]
    public string UserId { get; set; }

    [ForeignKey("UserId")]
    public AppUser User { get; set; }

    [Required]
    public string FirstName { get; set; }

    [Required]
    public string LastName { get; set; }

    [CollectionRequired(MinimumCollectionCount = 1)]
    public ICollection<Address> Addresses { get; set; }

    [CollectionRequired(MinimumCollectionCount = 1)]
    public ICollection<Email> Emails { get; set; }

    [CollectionRequired(MinimumCollectionCount = 1)]
    public ICollection<PhoneNumber> PhoneNumbers { get; set; }

    public ICollection<NotificationHistory> NotificationHistory { get; set; }
    public long TimeZoneId { get; set; }
    public long? ImageId { get; set; }

    [ForeignKey("ImageId")]
    [InverseProperty("User")]
    public Document Image { get; set; } 

    [ForeignKey("TimeZoneId")]
    public virtual TimeZone TimeZone { get; set; }


    [Key]
    public long Id { get; set; }
}

I have commented out the Fluent API Code

Unable to determine the principal end of an association between the types 'StACS.PeoplesVoice.DataAccessLayer.EntityModels.User.Details' and 'StACS.PeoplesVoice.DataAccessLayer.EntityModels.Configuration.Document'. The principal end of this association must be explicitly configured using either the relationship fluent API or data annotations.

2
c#entity-frameworkdata-annotationsef-fluent-api

2 Answers

3
votes

You can achieve same with Data Annotation as well, you are missing InverseProperty attribute, which resolves ambiguity in this case. Conceptually, every navigation property has Inverse Navigation property, EF automatically detects and assumes inverse property based on type, but if two entities are related to each other by multiple FK properties, you have to explicitly specify InverseProperty attribute on corresponding navigation properties.

I would recommend putting InverseProperty on every navigation property, which helps reduce startup time for EF as EF does not have to determine and validate the model.

Example,

public class AccountEmail {

    public long AccountID {get;set;}

    // Inverse property inside Account class
    // which corresponds to other end of this
    // relation
    [InverseProperty("AccountEmails")]
    [ForeignKey("AccountID")]
    public Account Account {get;set;}

}

public class Account{

    // Inverse property inside AccountEmail class
    // which corresponds to other end of this
    // relation
    [InverseProperty("Account")]
    public ICollection<AccountEmail> AccountEmails {get;set;}
}

I have written a text template which generates all these navigation properties based on current schema. Download all three files from https://github.com/neurospeech/atoms-mvc.net/tree/master/db-context-tt, you might have to customize this as it adds few more things based on our framework, but it does generate pure code model from your database directly.

1
votes

OK I finally figured this out. Sadly this is not very straight forward as I think Data Annotation should work BUT it does not.

You HAVE to use Fluent API:

        modelBuilder.Entity<Details>()
                    .HasOptional(x => x.Document)
                    .WithMany()
                    .HasForeignKey(x => x.ImageId);

        modelBuilder.Entity<Document>()
                    .HasRequired(x => x.User)
                    .WithMany()
                    .HasForeignKey(x => x.AddedByUser);