I get the following error when using Entity Framework:
Unable to determine the principal end of an association between the types
'xxx.Domain.Entities.UserSettings' and 'xxx.Domain.Entities.User'. The
principal end of this association must be explicitly configured using either
the relationship fluent API or data annotations.
Here are the two Entity classes:
public class User
{
[Key, Column("un")]
public string Username { get; set; }
public int Level { get; set; }
public virtual UserSettings UserSettings { get; set; }
}
public class UserSettings
{
[Key]
public string Username { get; set; }
public int ActiveRefresh { get; set; }
[ForeignKey("Username")]
public virtual User User { get; set; }
}
I am not sure how to resolve this error. I am stuck with the database design so I can't update that to fix the issue. Is there a way using Fluent Api to get these associations working?
A User can have a UserSettings object. This is the relationship that is desired.
It looks like you need a one to zero-or-one relationship
// Configure the primary key for the User
modelBuilder.Entity<User>()
.HasKey(t => t.Username);
// Map one-to-zero or one relationship
modelBuilder.Entity<UserSettings>()
.HasRequired(t => t.User)
.WithOptional(t => t.UserSettings);
This is not tested! Remove all the annotations from the entity classes. The link to Fluent API relationships in my comment above has more examples of the different kinds of relationship.
using anotations :
public class User
{
[Key, Column("un")]
public string Username { get; set; }
public int Level { get; set; }
//here is your foreign to UserSettings
public int? UserSettingsID{ get; set; }
[ForeignKey("UserSettingsID")] // not needed if you're using the '%ID' convention
//Navigation property
public virtual UserSettings UserSettings { get; set; }
}
public class UserSettings
{
//UserSettings PK
public int UserSettingsID{ get; set; }
public int ActiveRefresh { get; set; }
}
I assume here that you don't need to retrieve the user from his settings
Related
I am creating a relationship between my classes using code first. The integration happens with MySql, however, after migrating it consider the relationship as one-to-many when I check my workbench ERD.
How can I make a relashionship one-to-one using the classes mentioned below?
Here is my code:
public class About
{
[ForeignKey("User")]
public int Userid { get; set; }
public int id { get; set; }
public string about_file { get; set; }
public string about_desc { get; set; }
public virtual User User { get; set; }
}
public class User
{
[Key]
public int id { get; set; }
public string login { get; set; }
public string password { get; set; }
public virtual About About { get; set; }
public ICollection<Offers> Offers { get; set; } = new List<Offers>();
public ICollection<Portfolio> Portifolios { get; set; } = new List<Portfolio>();
}
Microsoft.EntityFrameworkCore Version: {5.0.7}
It is a one-to-one relationship by convention only. Having a navigation property instead of a collection, ensures that only one child entity can be related to one parent from Entity Framework's perspective. But on the database level, there is nothing that prevents the creation of multiple child entities.
If you want to enforce it on the database level, add a UNIQUE constraint to the foreign key on the child entity, or make the primary keys on both entities identical and make that the foreign key instead.
I am aware of other questions on the same topic, however I have tried their solutions and none have worked for my code.
I am configuring a one-to-many relationship with one Account with many JoinedClassIds.
Account.cs
public class Account {
// Actual account info
[Key]
public int _id { get; set; }
public string _name { get; set; }
public string _email { get; set; }
public ICollection<JoinedClassId> JoinedClasses { get; set; }
}
JoinedClassId.cs
[Keyless]
public class JoinedClassId {
public int classIdNumber { get; set; }
public Account Account { get; set; }
}
DBContext
public DbSet<Account> Accounts { get; set; }
public DbSet<JoinedClassId> JoinedClassIds { get; set; }
protected override void OnModelCreating(ModelBuilder modelBuilder) {
modelBuilder.Entity<Account>()
.HasMany(acc => acc.JoinedClasses)
.WithOne(jcid => jcid.Account);
modelBuilder.Entity<JoinedClassId>()
.HasOne(jc => jc.Account)
.WithMany(acc => acc.JoinedClasses);
modelBuilder.Entity<JoinedClassId>()
.HasNoKey();
}
I get the error
System.InvalidOperationException: 'Unable to determine the
relationship represented by navigation 'Account.JoinedClasses' of type
'ICollection'. Either manually configure the
relationship, or ignore this property using the '[NotMapped]'
attribute or by using 'EntityTypeBuilder.Ignore' in
'OnModelCreating'.'
What can I do to fix this?
Keyless entities cannot participate in two way relationships. They can only contain reference navigation to other regular entities (entities with key). Also, regular entities cannot contain navigation properties to keyless entity types. What causing the issue in your case is, your Account entity contains the navigation property JoinedClasses, which is a collection of Keyless entity.
For details - Keyless entity types characteristics
Remove the [Keyless] attribute from JoinedClassId entity
Add a new key property or mark the classIdNumber property as key
Add a foreign-key property (optional)
public class JoinedClassId
{
[Key]
public int Id { get; set; } // added key property
public int classIdNumber { get; set; }
public int AccountId { get; set; } // added foreign-key property
public Account Account { get; set; }
}
Then you can configure as -
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
modelBuilder.Entity<Account>()
.HasMany(acc => acc.JoinedClasses)
.WithOne(jcid => jcid.Account)
.HasForeignKey(p=> p.AccountId); // if you have added a foreign-key property
}
Fix your classes:
public class Account {
[Key]
public int Id { get; set; }
public string Name { get; set; }
public string Email { get; set; }
public virtual ICollection<JoinedClass> JoinedClasses { get; set; }
}
public class JoinedClass {
[Key]
public int Id { get; set; }
public int ClassIdNumber { get; set; }
public int AccountId { get; set; }
public virtual Account Account { get; set; }
}
If you use EF Net5 , you don't need OnModelCreating fluent Api code. Delete all tables from db and migrate again
I've just started using Entity Framework for my next project and I'm struggling with the following. I have the following ApplicationUser class:
public class ApplicationUser : IdentityUser
{
public string Name { get; set; }
public int CompanyId { get; set; }
public virtual Company Company { get; set; }
}
I have two classes that inherent from this class:
public class TrainerUser : ApplicationUser
{
public virtual ICollection<ClientUser> Clients { get; set; }
}
public class ClientUser : ApplicationUser
{
public string TrainerId { get; set; }
public TrainerUser Trainer { get; set; }
}
The company class looks like this:
public class Company
{
public int Id { get; set; }
public string Name { get; set; }
public virtual ICollection<TrainerUser> Trainers { get; set; }
public virtual ICollection<ClientUser> Clients { get; set; }
}
What I can't figure out is how I can use the fluent API to not include 3 different companyId columns in the ApplicationUsers table.
Currently I have the following fluent API configuration:
modelBuilder.Entity<TrainerUser>().HasRequired(c => c.Company).WithMany(t => t.Trainers).HasForeignKey(c => c.CompanyId);
modelBuilder.Entity<ClientUser>().HasRequired(c => c.Company).WithMany(c => c.Clients).HasForeignKey(c => c.CompanyId);
Can anyone point me in the right direction?
Try adding these to your code.
modelBuilder.Entity<TrainerUser>().ToTable("TrainerUser");
modelBuilder.Entity<ClientUser>().ToTable("ClientUser");
If I am getting you right. you are trying to create a structure representing Table Per Hierarchy (TPT). Read more about it at the link.
Basically what happens is when entity framework encounters inheritance in the entities. Its Default attempt to create tables is by creating column of the set of all properties of all the derived entities from a class with a discriminator column.
What you are trying to create is a separate table for every class in the hierarchy.
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.
I need help creating the relationship in entity framework as everything I have tried gives me errors when trying to add the migration or if I get passed that then I try to update the database and get an error about indexes with the same name.
public class Profile
{
public Profile()
{
Environments = new HashSet<Environment>();
}
[Key]
public int Id { get; set; }
public string VersionCreated { get; set; }
public string DiskLocation { get; set; }
public string Name { get; set; }
public DateTime DateTime { get; set; }
public virtual Product Product { get; set; }
public virtual Instance OriginalInstance { get; set; }
public virtual ICollection<Environment> Environments { get; set; }
}
public class Instance
{
public Instance()
{
TestResults = new HashSet<TestResult>();
Environments = new HashSet<Environment>();
}
[Key]
public int Id { get; set; }
public string Name { get; set; }
public string Version { get; set; }
public string UserFriendlyName { get; set; }
public virtual Product Product { get; set; }
public virtual Profile LastKnownProfile { get; set; }
public virtual Computer Computer { get; set; }
public virtual ICollection<TestResult> TestResults { get; set; }
public virtual ICollection<Environment> Environments { get; set; }
}
The problem with the above classes is that the OrginalInstance property on the Profile class and the LastKnownProfile in the Instance class are supposed to just be foreign keys to those specific tables and they probably won't be the same very often. They can also both possibly be null.
I have tried:
modelBuilder.Entity<Instance>().HasRequired(i => i.LastKnownProfile);
modelBuilder.Entity<Profile>().HasRequired(p => p.OriginalInstance);
This gave me an Unable to determine the principal end of an association between the types 'EcuWeb.Data.Entities.Instance' and 'EcuWeb.Data.Entities.Profile'. The principal end of this association must be explicitly configured using either the relationship fluent API or data annotations. error.
and with:
modelBuilder.Entity<Instance>().HasRequired(i => i.LastKnownProfile).WithOptional();
modelBuilder.Entity<Profile>().HasRequired(p => p.OriginalInstance).WithOptional();
The database adds a foreign key reference back to itself.
...that the OrginalInstance property on the Profile class and the
LastKnownProfile in the Instance class are supposed to just be foreign
keys to those specific tables and they probably won't be the same very
often. They can also both possibly be null.
In this case you actually want two one-to-many relationships between Profile and Instance if I don't misunderstand your quote above. It would mean that many Profiles can have the same OriginalInstance and that many Instances can have the same LastKnownProfile. The correct mapping would look like this then:
modelBuilder.Entity<Profile>()
.HasOptional(p => p.OriginalInstance)
.WithMany()
.Map(m => m.MapKey("OriginalInstanceId"));
modelBuilder.Entity<Instance>()
.HasOptional(i => i.LastKnownProfile)
.WithMany()
.Map(m => m.MapKey("LastKnownProfileId"));
The lines with MapKey are optional. Without them EF will create a foreign key with a default name.
Also note that you must use HasOptional (instead of HasRequired) if "both can possibly be null".