I have a one-to-many relationship of order to payment:
public class Order
{
[Key]
public Guid SerialNumber { get; set; }
public string OrderNumber { get; set; }
...
[ForeignKey("OrderNumber")]
public virtual ICollection<Payment> Payments { get; set; }
}
public class Payment
{
[Key]
public string SerialNumber { get; set; }
public string OrderNumber { get; set; }
...
public decimal Amount { get; set; }
}
Despite the records being available, the Payments collection always shows 0 elements. I've looked at the trace and the problem seems to be with the generated SQL query - it's trying to match Order.SerialNumber to Payment.OrderNumber.
How can I resolve this, preferably with data annotations? Thanks in advance!
it's trying to match Order.SerialNumber to Payment.OrderNumber.
Yes because that is exactly what you have modeled. ForeignKey attribute doesn't describe the name of foreign key property in the related table. It describes the name of foreign key property in the same table and it is used to pair navigation property with its key so the correct usage is:
public class Order
{
[Key]
public Guid SerialNumber { get; set; }
public string OrderNumber { get; set; }
...
public virtual ICollection<Payment> Payments { get; set; }
}
public class Payment
{
[Key]
public string SerialNumber { get; set; }
// Foreign key must have the same type as primary key in the principal table
public Guid OrderNumber { get; set; }
...
public decimal Amount { get; set; }
// Reverse navigation property to principal associated with foreign key
[ForeignKey("OrderNumber")]
public virtual Order Order { get; set; }
}
If you don't want navigation property in Payment you have to use fluent API to describe the mapping:
modelBuilder.Entity<Order>()
.HasMany(o => o.Payments)
.WithRequired()
.HasForeignKey(p => p.OrderNumber);
If you have existing database and your relation really targets OrderNumber column in the Order table it means it must be marked with unique constraint - such relation currently cannot be mapped in EF because it doesn't support unique constraints yet.
Related
As you know that developers mostly mock the relationship between tables instead of using physical relationships between table (yeah, the line drawn from one table to another if you put a foreign key constraint on the column).
But I believe that Entity Framework doesn't work properly if physical relationships aren't there for navigational properties.
So, is there any way around?
My classes:
public class Phones
{
public int ID { get; set; }
public string Model { get; set; }
public string Manufacturer { get; set; }
public List<Users> Users { get; set; }
}
public class Sims
{
public int ID { get; set; }
public string Code { get; set; }
}
This creates a 1-M relationship from User -> Sims.
But what if I drop the foreign key constraint and leave it as it is, how will the navigational properties work then?
At this case better to remove references from both classes and handle relations manually outside of these classes:
public class Sims
{
public int ID { get; set; }
public string Code { get; set; }
//public User User { get; set; }
public int UserID { get; set; }
}
Based on the solution provided in this question : How to update foreign key in EF 6 - Code First, I'm able to update my foreign key using the id field.
But now, I get an exception when getting entities from the database. Using this code :
// Retrieve data first
using (var db = new TestDbContext())
{
var p2 = db.Persons.First();
}
I get the following SqlException : "Invalid column name 'Country_Id1'."
Does anyone have any clues to be able to retrieve data and to update the foreign key ?
Asked in another way, is it possible to use both the navigation property to ease the use of my entity and the id of the foreign key to be able to update my dependent entity ?
My entities
public class Person
{
public int Id { get; set; }
public string Name { get; set; }
public virtual Country Country { get; set; }
public int Country_Id { get; set; }
}
public class Country
{
public int Id { get; set; }
public string Name { get; set; }
}
That might be because entity framework is trying to create new foreign key based on navigation property Country in Person entity.
I think you should annotate Country_Id property with ForeignKey attribute as below.
public class Person
{
public int Id { get; set; }
public string Name { get; set; }
[ForeignKey("Country_Id")]
public virtual Country Country { get; set; }
public int Country_Id { get; set; }
}
However if you follow the ef naming convention for naming property as below, you don't need to annotate it.
Any property with the same data type as the principal primary key
property and with a name that follows one of the following formats
represents a foreign key for the relationship: '', '', or ''
You may read more from here
public class Person
{
public int Id { get; set; }
public string Name { get; set; }
public virtual Country Country { get; set; }
public int CountryId { get; set; }
}
Note: you might need to run database migration or need to recreate database.
I am having an issue mapping my tables together. I get the error:
Invalid column name 'Film_Id'.
Here are my Entities:
public class Film
{
[Key]
public Int32 Id { get; set; }
public String Title { get; set; }
public virtual ICollection<NormComparableFilm> NormComparableFilms { get; set; }
}
public class NormComparableFilm
{
[Key]
public Int32 Id { get; set; }
public Int32 FilmId { get; set; }
public Int32 ComparableFilmId { get; set; }
[ForeignKey("FilmId")]
public virtual Film Film { get; set; }
[ForeignKey("ComparableFilmId")]
public virtual Film ComparableFilm { get; set; }
}
Is there a custom mapping in the OnModelCreating() function that I need? I tried adding the following but it fails with a slightly different error:
modelBuilder.Entity<Film>()
.HasMany(f => f.NormComparableFilms)
.WithMany().Map(t => t.MapLeftKey("FilmId")
.MapRightKey("ComparableFilmId")
.ToTable("NormComparableFilms"));
The above gives this error:
Invalid object name 'dbo.NormComparableFilms1'.
I think I'm close but can't seem to get it just right. Any help would be appreciated.
The first error happened because you are creating two relationships between the same entities and Code First convention can identify bidirectional relationships, but not when there are multiple bidirectional relationships between two entities.The reason that there are extra foreign keys (Film_ID) is that Code First was unable to determine which of the two properties in NormComparableFilm that return a Film link up to the ICollection<NormComparableFilm> properties in the Film class. To resolve this Code First needs a little of help . You can use InverseProperty data annotation to specify the correct ends of these relationships, for example:
public class NormComparableFilm
{
[Key]
public int Id { get; set; }
public int FilmId { get; set; }
public int ComparableFilmId { get; set; }
[ForeignKey("FilmId")]
[InverseProperty("NormComparableFilms")]
public virtual Film Film { get; set; }
[ForeignKey("ComparableFilmId")]
public virtual Film ComparableFilm { get; set; }
}
Or remove the data annotation you already are using and add just these configurations:
modelBuilder.Entity<NormComparableFilm>()
.HasRequired(ncf=>ncf.Film)
.WithMany(f=>f.NormComparableFilms)
.HasForeignKey(ncf=>ncf.FilmId);
modelBuilder.Entity<NormComparableFilm>()
.HasRequired(ncf=>ncf.ComparableFilm)
.WithMany()
.HasForeignKey(ncf=>ncf.ComparableFilmId);
If in the second relationship, the ComparableFilm navigation property is optional, you need to change the type of the corresponding FK as nullable:
public class NormComparableFilm
{
//...
public int? ComparableFilmId { get; set; }
}
And use this configuration:
modelBuilder.Entity<NormComparableFilm>()
.HasOptional(ncf=>ncf.ComparableFilm)
.WithMany()
.HasForeignKey(ncf=>ncf.ComparableFilmId);
About the second error, you are trying to call the Film table as NormComparableFilms that is the default name that EF will give by convention to the table represented by the NormComparableFilm entity.
if you need to rename one of your tables, you can use this configuration:
modelBuilder.Entity<Film>().ToTable("Films"));
Writing a model for situation where I have two tables which are customers and users. Each user record might have an optional related customer record and vice versa, but none of them is a must. I figured out that FK Associations are not what I need, but Independent Associations are. But I just can find a way to make it work, I keep getting the 'Unable to determine the principal end...The principal end of this association must be explicitly configured using either the relationship fluent API or data annotations.' exception.
My models are very simple:
public class User
{
[Key]
public int Id { get; set; }
[StringLength(20)]
public string CustomerId { get; set; }
public string Password { get; set; }
public bool Locked { get; set; }
//[ForeignKey("CustomerId")]
public virtual Customer Customer { get; set; }
}
public class Customer
{
[Key]
[Column("Id", TypeName = "nvarchar")]
[StringLength(20)]
public string Id { get; set; } // nvarchar 20
[Required]
public string GivenName { get; set; } // nvarchar 100
[Required]
public string Surname { get; set; } // nvarchar 100
//[InverseProperty("Customer")]
public virtual User User { get; set; }
}
I've tried to add the ForeignKeyAttribute and InversePropertyAttribute, which are currently commented out, but they didn't help either. I would prefer to use data annotations and not fluent API, if it's possible in my case.
In one-to-one relation one end must be principal and second end must be dependent. Principal end is the one which will be inserted first and which can exist without the dependent one. Dependent end is the one which must be inserted after the principal because it has foreign key to the principal. When configuring one-to-one relationships, Entity Framework requires that the primary key of the dependent also be the foreign key.This problem is most easily solved by using a ForeignKey annotation on the dependent class to identify that it contains the foreign key. In your case, Customer could be the dependent and its key, Customer.UserId, should also be the foreign key. But both Keys must be declared using the same type:
public class User
{
[Key]
public int Id { get; set; }
public virtual Customer Customer { get; set; }
}
public class Customer
{
[Key, ForeignKey("User")]
public int UserId { get; set; }
public virtual User User{ get; set; }
}
I don't know how to resolve your problem using Data Annotations, but if you want to use Fluent Api, I think the configuration of the relationship would be like this:
modelBuilder.Entity<User>().HasOptional(u => u.Customer).WithOptionalPrincipal(c => c.User);
Update
I understand your escenario, but if you have the same columns that you show in your model, I think you should have a one-to-many relationship mapped in DB instead one-to-one. Try to map your relationship this way:
public class User
{
[Key]
public int Id { get; set; }
public string Password { get; set; }
public bool Locked { get; set; }
public string CustomerId { get; set; }
[ForeignKey("CustomerId")]
public virtual Customer Customer { get; set; }
}
public class Customer
{
[Key]
[Column("Id", TypeName = "nvarchar")]
[StringLength(20)]
public string Id { get; set; } // nvarchar 20
[Required]
public string GivenName { get; set; } // nvarchar 100
[Required]
public string Surname { get; set; } // nvarchar 100
public virtual ICollection<User> Users { get; set; }
}
Remember map your properties with the same column'names that you have in DB.
public class Product
{
[Key]
public int Id { get; set; }
public string Name { get; set; }
public string Description { get; set; }
public decimal Price { get; set; }
public bool IsInStock { get; set; }
public string ImageUrl { get; set; }
public List<ProductOption> ProductOptions { get; set; }
public virtual Category Category { get; set; }
}
public class ProductOption
{
[Key]
public int Id { get; set; }
public string ProductOptionName { get; set; }
public string ProductOptionDescription { get; set; }
}
Now I know when your using Code First EF, so that the tables are created correctly. You need to do something like this.
modelBuilder.Entity<Product>().HasMany(p => p.ProductOptions).WithMany().Map(m =>
{
m.MapLeftKey("ProductId").MapRightKey("ProductOptionId").ToTable("SelectedProductOptionsInOrderedItem");
});
So....
Does this mean that if I do something like Product.ProductOptions I will be able to access all associated productoptions.
Is this the best way to set it up, or is there another way?
To enable lazy load and EF can create derived proxy types for your collection, that property should be declared this way:
public virtual ICollection<ProductOptions> ProductOptions { get; set; }
That should be enought. Other aspect is the mapping approach that you use. You choose fluent api, i prefer mapping by convention, but that is a matter of personal taste anyway.
Ok, Mapping by Conventions:
Is the ability of EF that from the name of entities and their properties along with their types, to map our model with the underlying data without providing any other information.
for example
public class Customer {
public long CustomerID {get; September;}
public string CustomerName {get; September;}
public Employee AssignedTo {get; September;}
}
With the previous model EF will map database with a table named Customer with:
. CustomerID bigint primary key column
. CustomerName nvarchar column
. Customer_EmployeeID foreign key to Employee table, with the datatype Corresponding to EmployeeID in that table.
You can read more Here