I Got This Issue:
I Have the Application User Class Like This
public class ApplicationUser : IdentityUser
{
public ROLES Role { get; set; }
public int? CompanyId { get; set; }
public int? AreaId { get; set; }
public string Document { get; set; }
public bool Enable { get; set; }
[ForeignKey("CompanyId")]
public virtual Company Company { get; set; }
[ForeignKey("AreaId")]
public virtual Area Area { get; set; }
public virtual ICollection Measures { get; set; }
}
And I Got this another Model:
public class Area
{
public int AreaId { get; set; }
public string AreaName { get; set; }
public int CompanyId { get; set; }
public string UserId { get; set; }
[ForeignKey("CompanyId")]
public virtual Company Company { get; set; }
[Key, ForeignKey("UserId")]
public ApplicationUser ApplicationUser { get; set; }
}
And when i try to:
add-migration
the PM Console throws:
Unable to determine the principal end of an association between the types 'x.Models.ApplicationUser' and 'x.Models.Area'. The principal end of this association must be explicitly configured using either the relationship fluent API or data annotations.
I have been trying all day but I can't find a way to tell the Entity Framework to recognize the relation.
Any ideas?
Thanks for reading
Add Attribute for AreaId in Area class
[Key]
public int AreaId { get; set; }
and if you want 1-1 relationship for ApplicationUser and Area update your code like
[Unique]
[ForeignKey("UserId")]
public ApplicationUser ApplicationUser { get; set; }
The principal end of this association must be explicitly configured using either the relationship fluent API or data annotations
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Thanks for all of your help!
Related
I'm using Net Core 2.2 and Entity Framework. I have an ApplicationUser class used for multiple user types with foreign keys to each other but entity framework gives an error when adding a migration:
Unable to determine the relationship represented by navigation property 'ApplicationUser.Class' of type 'Class'. Either manually configure the relationship, or ignore this property using the '[NotMapped]' attribute or by using 'EntityTypeBuilder.Ignore' in 'OnModelCreating'.
I'm unsure what the proper way to implement this is. Can anyone help me?
My ApplicationUser class:
public class ApplicationUser : IdentityUser
{
public string CustomerId { get; set; }
public string TeacherId { get; set; }
public int? ClassId { get; set; }
public int? SettingsId { get; set; }
public virtual ApplicationUser Customer { get; set; }
public virtual ApplicationUser Teacher { get; set; }
public virtual Class Class { get; set; }
public virtual Settings Settings { get; set; }
public virtual ICollection<Class> Classes { get; set; }
public virtual ICollection<License> Licenses { get; set; }
public virtual ICollection<Exercise> Exercises { get; set; }
public virtual ICollection<GameProgress> GameProgresses { get; set; }
public virtual ICollection<StudentExercise> StudentExercises { get; set; }
}
And because it's in the error, my Class class:
public class Class
{
public int Id { get; set; }
public string TeacherId { get; set; }
public int? SettingsId { get; set; }
public virtual ApplicationUser Teacher { get; set; }
public virtual Settings Setting { get; set; }
public virtual ICollection<Exercise> Exercises { get; set; }
public virtual ICollection<ApplicationUser> Students { get; set; }
}
The problem has nothing to do with self-referential ApplicationUser relationships. The exception specifically tells you this is a problem with Class. The issue is that you've got a reference property to Class on ApplicationUser, but on Class, you've got both a collection of ApplicationUsers (Students) and a separate reference to ApplicationUser (Teacher). Simply, EF doesn't know which this foreign key is actually referring to.
The solution is exactly what the exception tells you: add fluent config to clear up the ambiguity:
public override void OnModelCreating(ModelBuilder modelBuilder)
{
modelBuilder.Entity<ApplicationUser>()
.HasOne(x => x.Class)
.WithMany(x => x.Students);
}
I am trying to enable migrations on a new db that includes the following table relationship:
where HolderID can be NULL. Running enable-migrations gives the error message of "Unable to determine the principal end of an association"
My 2 classes are as follows:
public class Competitor
{
[Key]
public int ID { get; set; }
public string FirstName { get; set; }
public string LastName { get; set; }
public string FullName { get { return string.Format("{0} {1}", FirstName, LastName); } }
public virtual Championship Championship { get; set; }
}
public class Championship
{
[Key]
public int ID { get; set; }
public string Name { get; set; }
public int? HolderID { get; set; }
[ForeignKey("HolderID")]
public virtual Competitor Holder { get; set; }
}
I don't understand how I need to correct my model to reflect the desired database schema structure. I would prefer to use Annotations over fluent api, if possible.
Thanks in advance.
public virtual Championship Championship { get; set; }
needed to be
public virtual ICollection<Championship> Championships { get; set; }
I'm trying to create my database from my models, but I keep getting the error Introducing FOREIGN KEY constraint 'FK_dbo.Reports_dbo.UserProfiles_UserId' on table 'Reports' may cause cycles or multiple cascade paths. Specify ON DELETE NO ACTION or ON UPDATE NO ACTION, or modify other FOREIGN KEY constraints.
Could not create constraint. See previous errors.
anyone knows what might be wrong with my models/setup?
These are all used Models
public class Report {
[Key]
public int Id { get; set; }
[Required]
public string Number { get; set; }
public bool Synced { get; set; }
public DateTime CreationDate { get; set; }
public int NewCommentId { get; set; }
public virtual Comment NewComment { get; set; }
public int UserId { get; set; }
public virtual UserProfile User { get; set; }
public virtual ICollection<Comment> Comments { get; set; }
public virtual ICollection<Photo> PhotosBefore { get; set; }
public virtual ICollection<Photo> PhotosAfter { get; set; }
}
public class Photo {
[Key]
public int Id { get; set; }
public string Image { get; set; }
public bool Synced { get; set; }
public DateTime CreationDate { get; set; }
public int ReportId { get; set; }
public virtual Report Report { get; set; }
public int UserId { get; set; }
public virtual UserProfile User { get; set; }
}
public class Comment {
[Key]
public int Id { get; set; }
public DateTime CreationDate { get; set; }
public string Text { get; set; }
public int ReportId { get; set; }
public virtual Report Report { get; set; }
public int UserId { get; set; }
public virtual UserProfile User { get; set; }
}
public class UserProfile {
[Key]
public int Id { get; set; }
public string Stamnummer { get; set; }
public string Leverancier { get; set; }
public virtual ICollection<Comment> Comments { get; set; }
public virtual ICollection<Report> Reports { get; set; }
public virtual ICollection<Photo> Photos { get; set; }
}
In order to be certain, we need to see how you have configured your relationships using the model builder in the OnModelCreating method. Based on the error message you have provided, it appears that you have relationships configured so that one of your entities is configured for cascade on delete from two or more other entities.
As an example (this may not be the case, but rather just a means of describing the problem):
User has a one-to-many relationship with Comments
User has a one-to-many relationship with Reports
Report has a one-to-many relationship with Comments
Comment is configured so that a User is required
Comment is configured so that a Report is required
Report is configured so that a User is required
Any one-to-many relationship where the entity one side of the relationship is required is going to have cascade on delete configured by default. In this scenario, if a User were deleted it would trigger a cascade to both Reports and Comments. Each Report would also cause a cascade on Comments.
The solution is to disable cascading deletes for one of the relationships. You can find a similar question to yours here describing what I mentioned above.
I'm designing a multi tenant website using EF6 code first, MVC, and other from the MS stack.
I want to have announcements for each Tenant. Simple enough, my EF code first class would look something like this:
class Announcement
{
public Announcement()
{
DateCreated = DateTime.Now;
}
[Key]
public int Id { get; set; }
public DateTime DateCreated { get; set; }
public string Title { get; set; }
public string Message { get; set; }
public virtual Tenant Tenant { get; set; }
public ApplicationUser Author { get; set; }
}
My design question is what if I want the site administrator to have the ability to post announcements to all tenants?
Since the database will force the Tenant relationship, I can't set the Tenant property to something artificial.
Before EF, I'd do something like this, but now I will lose the nice-to-have EF Navigation property.
class Announcement
{
public Announcement()
{
DateCreated = DateTime.Now;
}
[Key]
public int Id { get; set; }
public DateTime DateCreated { get; set; }
public string Title { get; set; }
public string Message { get; set; }
public int TenantID { get; set; }
public ApplicationUser Author { get; set; }
}
I would use TenantID appropriately for all Tenant based announcements, but would set it to 0 for site wide announcements.
So, is there a better design (other than two classes/tables) that can still leverage the EF Navigation properties?
What is the issue with
class Announcement
{
public Announcement()
{
DateCreated = DateTime.Now;
}
[Key]
public virtual int Id { get; set; }
public virtual DateTime DateCreated { get; set; }
public virtual string Title { get; set; }
public virtual string Message { get; set; }
public virtual int TenantID { get; set; } // during insert/Update set as required. the tenant should exist.
// A dummy SYSTEM wide tenant may be an option to consider
// navigation props
[ForeignKey("TenantID")]
public virtual Tenant Tenant { get; set; } // <<<<< NAV as before
public virtual ApplicationUser Author { get; set; }
}
Here are my models
public class Driver
{
public int Id { get; set; }
public String Name { get; set; }
public int VehicleId { get; set; }
public virtual Vehicle Vehicle { get; set; }
}
public class Vehicle
{
public int Id { get; set; }
public String Name { get; set; }
public virtual Driver Driver { get; set; }
public int VehicleGroupId { get; set; }
public virtual VehicleGroup Vehicles { get; set; }
}
I'm getting the following error on updating database:
Unable to determine the principal end of an association between the types 'AppName.Models.Vehicle' and 'AppName.Models.Driver'. The principal end of this association must be explicitly configured using either the relationship fluent API or data annotations.
I wish to solve the issue using data annotations. I've tried putting foreign key attribute over Driver Navigation property in vehicle model. But no success. Any help is much appreciated.
To solve your problem you need to explicitly set the end of the association like this :
public class Vehicle
{
[Key, ForeignKey("Driver")]
public int Id { get; set; }
public String Name { get; set; }
public virtual Driver Driver { get; set; }
public int VehicleGroupId { get; set; }
public virtual VehicleGroup Vehicles { get; set; }
}
I think your model is inccorect because a driver can use many vehicles in real life ;)