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The INSERT statement conflicted with the FOREIGN KEY constraint "FK_Users_Agencies_UserID"

im using entity framework core 5.0 and i created my one to many relationship with fluent api.
im getting that error when i try to create a new user in my project.
let me show u to my User class:
public class User : Base
{
[Key]
public int UserID { get; set; }
public string UserName { get; set; }
public string UserSurname { get; set; }
public string UserPassword { get; set; }
public string UserEMail { get; set; }
public int? AgencyID { get; set; }
public virtual Agency Agency { get; set; }
}
public class UserConfiguration : IEntityTypeConfiguration<User>
{
public void Configure(EntityTypeBuilder<User> builder)
{
builder.HasKey(user => user.UserID);
}
}
and here its a Agency class which is related to User class:
public class Agency : Base
{
[Key]
public int AgencyID { get; set; }
public string AgencyName { get; set; }
public string AgencyPhoto { get; set; }
public string AgencyEMail { get; set; }
public string AgencyPhone { get; set; }
public int AgencyExportArea { get; set; }
public virtual ICollection<User> Users { get; set; }
}
public class AgencyConfiguration : IEntityTypeConfiguration<Agency>
{
public void Configure(EntityTypeBuilder<Agency> builder)
{
builder.HasKey(agency => agency.AgencyID);
builder.HasMany(us => us.Users)
.WithOne(us => us.Agency)
.HasForeignKey(au => au.UserID)
.IsRequired(false)
}
}
i know,im getting that error SqlException: The INSERT statement conflicted with the FOREIGN KEY constraint "FK_Users_Agencies_UserID". The conflict occurred in database "anan", table "dbo.Agencies", column 'AgencyID'. because there is a no data in Agency table. The thing which im trying to do is make that AgencyID foreign key optional as a nullable. in User class u can see i defined that AgencyID as a nullable.
do i really need to define that relationship as a one-to-one or zero or is there a another way to do that ?
if i have to define that relationship as a one-to-one or zero,can u show me the way how can i do that.

Since you are using EF core 5 you don't need:
public class UserConfiguration : IEntityTypeConfiguration<User>
and
public class AgencyConfiguration : IEntityTypeConfiguration<Agency>
All this code is reduntant. You have a standart one-to-many relation that EF core recognizes and configures by default. Remove all of this code and everything will be fine.
But if you are a student and need to do everything hard way, you can add this reduntant code:
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
modelBuilder.Entity<User>(entity =>
{
entity.HasOne(d => d.Agency)
.WithMany(p => p.Users)
.HasForeignKey(d => d.AgencyId)
.OnDelete(DeleteBehavior.ClientSetNull);
});
}
And since you are interested in a configuration, these are another redundant attributes:
public class User : Base
{
[Key]
public int UserID { get; set; }
.....
public int? AgencyID { get; set; }
[ForeignKey(nameof(AgencyId))]
[InverseProperty("Users")]
public virtual Agency Agency { get; set; }
}
public class Agency : Base
{
[Key]
public int AgencyID { get; set; }
.....
[InverseProperty(nameof(User.Agency))]
public virtual ICollection<User> Users { get; set; }
}

Exception in Entity Framework SaveChanges?

I'm trying to make an insert in a SQL database using Entity Framework 6 and I'm stuck on this issue that I cannot solve.
The error that I keep getting is :
UpdateException: Entities in 'Connect.CompanyFinancialDetails' participate in the 'Company_CompanyFinancialDetails' relationship. 0 related 'Company_CompanyFinancialDetails_Source' were found. 1 'Company_CompanyFinancialDetails_Source' is expected
I have these 2 entities:
public class Company
{
public long CUI { get; set; }
public string UserName { get; set; }
public string CompanyName { get; set; }
public string Symbol { get; set; }
public int? SharesCount { get; set; }
public decimal? SharePrice { get; set; }
public virtual Account Account { get; set; }
public virtual CompanyFinancialDetails CompanyFinancialDetails { get; set; }
}
public class CompanyFinancialDetails
{
[Key]
[DatabaseGenerated(DatabaseGeneratedOption.Identity)]
public int Id { get; set; }
// other properties
public decimal? NumberOfEmployees { get; set; }
public virtual Company Company { get; set; }
}
This is the Fluent API configuration:
public DbSet<Account> SignUpModels { get; set; }
public DbSet<Company> Companies { get; set; }
public DbSet<CompanyFinancialDetails> CompanyFinancialDetails { get; set; }
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
modelBuilder.Entity<Account>()
.HasKey(k => k.Id)
.HasOptional(s => s.Company)
.WithRequired(d => d.Account);
modelBuilder.Entity<Company>()
.HasKey(k => k.CUI)
.HasOptional(s => s.CompanyFinancialDetails)
.WithRequired(d => d.Company);
}
The relationship that I want to have is 1-many (one Company has many CompanyFinancialDetails).
This is the code where I add the objects to the database:
Company co = Context.Find(username);
foreach (CompanyFinancialDetails s in c)
{
s.Company = co;
}
a.CompanyFinancialDetails.AddRange(c);
a.SaveChanges();
I get a list of CompanyFinancialDetails and I add them using the AddRange method. I had this issue before and what I did was to add the virtual property object to the object that I wanted to insert in the database and it worked. This is what I tried to do here: the Find() method gets the company object that is related to the CompanyFinancialDetails and for each CompanyFinancialDetails object an Company virtual property is adding the related company object.
Well, it didn't work, when the SaveChanges() method is called, I get that error. Any help would be appreciated.

Entity Framework: The Entity with schema was already defined

In my database, I have two tables, namely Book and User, that have a M-to-M relationship table named BookXUser. In the relationship table, there are two fields, which are the foreign keys of the Book and User, and another field named bookShelf. Since using only Entity Framework I couldn't find a way to insert a M-to-M relationship while inserting into the bookShelf at the same time, I decided to make a model for the relationship table, which are defined like this:
modelBuilder.Entity<Book>()
.HasMany<UserData>(s => s.user)
.WithMany(c => c.book)
.Map(cs =>
{
cs.MapLeftKey("bookID");
cs.MapRightKey("userID");
cs.ToTable("BookXUser");
});
modelBuilder.Entity<BookXUser>()
.HasRequired<UserData>(s => s.user)
.WithMany(g => g.bookXuser)
.HasForeignKey<int>(s => s.userID);
modelBuilder.Entity<BookXUser>()
.HasRequired<Book>(s => s.book)
.WithMany(g => g.bookXuser)
.HasForeignKey<int>(s => s.bookID);
The problems arrive when I execute the following line:
userDataRepo.FindBy(user => user.email == entry.email).FirstOrDefault()
The EntitySet 'BookUserData' with schema 'dbo' and table 'BookXUser' was already defined. Each EntitySet must refer to a unique schema and table.
How can I solve this error while keeping the relationship table as a model which references the BookXUser? The idea is that I am using lazy loading on the virtual methods found in the model of BookXUser so I can get my books and users more easily, and I also manually insert my data in it so I can populate the bookshelf field.
public class BookXUser : IEntityBase
{
public int ID { get; set; }
public int bookID { get; set; }
public virtual Book book { get; set; }
public int userID { get; set; }
public virtual UserData user { get; set; }
public string bookShelf { get; set; }
}
The Book entity
public class Book : IEntityBase
{
public int ID { get; set; }
public string title { get; set; }
public string isbn { get; set; }
public int noPage { get; set; }
public string edition { get; set; }
public string bLanguage { get; set; }
public byte[] bookPic { get; set; }
public string publisherSite { get; set; }
public string bookFormat { get; set; }
public DateTime releaseDate { get; set; }
public DateTime initialReleaseDate { get; set; }
public string publisher { get; set; }
public string overview { get; set; }
public virtual ICollection<Author> author { get; set; }
public virtual ICollection<Genre> genre { get; set; }
public virtual ICollection<UserData> user { get; set; }
public virtual ICollection<Rating> rating { get; set; }
public virtual ICollection<Review> review { get; set; }
public virtual ICollection<BookXUser> bookXuser { get; set; }
public Book()
{
this.author = new HashSet<Author>();
this.genre = new HashSet<Genre>();
this.user = new HashSet<UserData>();
this.rating = new HashSet<Rating>();
this.review = new HashSet<Review>();
this.bookXuser = new HashSet<BookXUser>();
}
}
The UserData enity
public class UserData : IEntityBase
{
public int ID { get; set; }
public string username { get; set; }
public string userpass { get; set; }
public string email { get; set; }
public byte[] userPic { get; set; }
public string userOverview { get; set; }
public DateTime joinedDate { get; set; }
public virtual ICollection<Book> book { get; set; }
public virtual ICollection<Review> review { get; set; }
public virtual ICollection<Rating> rating { get; set; }
public virtual ICollection<UserData> user { get; set; }
public virtual ICollection<BookXUser> bookXuser { get; set; }
public UserData()
{
this.book = new HashSet<Book>();
this.review = new HashSet<Review>();
this.rating = new HashSet<Rating>();
this.user = new HashSet<UserData>();
this.bookXuser = new HashSet<BookXUser>();
}
}

You defined your Book and UserData entities in a wrong way. As you say in your question you are trying to define a many-to-many relashionship between Book and UserData so you added a join entity BookXUser because that entity hold a data BookShelf. That join entity will use by convention BookXUser as a table name.
Also, you defined two collections:
ICollection<UserData> user in your Book entity
ICollection<Book> book in your UserData entity
You also use this fluent configuration in your OnModelCreating method:
modelBuilder.Entity<Book>()
.HasMany<UserData>(s => s.user)
.WithMany(c => c.book)
.Map(cs =>
{
cs.MapLeftKey("bookID");
cs.MapRightKey("userID");
cs.ToTable("BookXUser"); // <-- this is your error.
});
Doing it like this, you're adding another many-to-many relashionship between Book and UserData and use BookXUser as the name for the join table which is already used by your entity BookXUser you've created.
To solve your issue you don't need to add the collections and to configure many-to-many relationship fluently like you did. Why? Bacause you have an join entity BookXUser.
So :
remove ICollection<UserData> user from your Book entity and replace it with ICollection<BookXUser> BookXUser
remove ICollection<Book> book from your UserData entity and replace it with ICollection<BookXUser> BookXUser
remove the fluent configuration you added for many-to-many relashionship between UserData and Book.

Entity Framework - Multiple Foreign Keys Issue

I have a Project model which has a ProjectLead (one instance of the Person Foreign Key), this works fine. But now I also need to add a collection of People (Project members) referencing the same Person table and I can't get the Entity Framework to generate my database. As soon as I try to add the Fluent API code to create the link table ProjectPerson I get an error - "Schema specified is not valid. Errors: The relationship 'MyApp.WebApi.Models.Person_Projects' was not loaded because the type 'MyApp.WebApi.Models.Person' is not available." I assume this is because of the existing FK relationship already in place with ProjectLead.
Project Model:
public class Project
{
[Key]
public int ProjectId { get; set; }
public string Name { get; set; }
// Foreign Key - Project lead (Person)
public int ProjectLeadId { get; set; }
public virtual Person ProjectLead { get; set; }
// Create many to many relationship with People - Team members on this project
public ICollection<Person> People { get; set; }
public Project()
{
People = new HashSet<Person>();
}
}
Person Model:
public class Person
{
[Key]
public int PersonId { get; set; }
public String Firstname { get; set; }
public String Surname { get; set; }
// Create many to many relationship
public ICollection<Project> Projects { get; set; }
public Person()
{
Projects = new HashSet<Project>();
}
}
DB Context:
public class HerculesWebApiContext : DbContext
{
public DbSet<Person> People { get; set; }
public DbSet<Project> Projects { get; set; }
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
// This works fine
modelBuilder.Entity<Project>()
.HasRequired(c => c.ProjectLead)
.WithMany(d => d.Projects)
.HasForeignKey(c => c.ProjectLeadId)
.WillCascadeOnDelete(false);
// Adding these lines to create the link table `PersonProjects` causes an error
//modelBuilder.Entity<Person>().HasMany(t => t.Projects).WithMany(t => t.People);
//modelBuilder.Entity<Project>().HasMany(t => t.People).WithMany(t => t.Projects);
}
}
I gather that perhaps I need to use the InverseProperty attribute, but I am not sure where this should go in this case?

Can you explicitly define your join table? So, define a ProjectPeople relationship and make the code something like this...
public class ProjectPerson{
[Key]
public int ProjectPersonId { get; set; }
[ForeignKey("Project")]
public int? ProjectId {get;set;}
public virtual Project {get;set;}
[ForeignKey("Person")]
public int? PersonId {get;set;}
public virtual Person {get;set;}
public string RelationshipType {get;set;}
}
Then your other 2 classes will look like this...
public class Project
{
[Key]
public int ProjectId { get; set; }
public string Name { get; set; }
// Foreign Key - Project lead (Person)
public int ProjectLeadId { get; set; }
public virtual Person ProjectLead { get; set; }
// Create many to many relationship with People - Team members on this project
public virtual ICollection<ProjectPerson> ProjectPeople { get; set; }
public Project()
{
ProjectPerson = new HashSet<ProjectPerson>();
}
}
And this..
Public class Person
{
[Key]
public int PersonId { get; set; }
public String Firstname { get; set; }
public String Surname { get; set; }
// Create many to many relationship
public virtual ICollection<ProjectPerson> ProjectPeople { get; set; }
public Person()
{
ProjectPerson = new HashSet<ProjectPerson>();
}
}

Asp .NET MVC - Entity Framework many to many relationship, insert data

I have the model:
public class Movie
{
[Key]
public int MovieId { get; set; }
public string Title{ get; set; }
public ICollection<Actor> Actors { get; set; }
}
public class Actor
{
[Key]
public int AtorId { get; set; }
public string Nome { get; set; }
public ICollection<Movie> Movies { get; set; }
}
and the context:
public class MoviesContext : DbContext
{
public DbSet<Movie> Movies { get; set; }
public DbSet<Actor> Actors { get; set; }
public MoviesContext()
{
Database.SetInitializer(new DropCreateDatabaseIfModelChanges<MoviesContext>());
}
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
modelBuilder.Conventions.Remove<PluralizingTableNameConvention>();
modelBuilder.Entity<Movie>().
HasMany(m => m.Actors).
WithMany(a => a.Movies).
Map(
m =>
{
m.MapLeftKey("MovieId");
m.MapRightKey("ActorId");
m.ToTable("ActorsMovies");
});
}
}
The table "ActorsMovies" is already created on sql server. how do I insert data into this table with entity framework? To insert data on the table Movies, for example, i've used the code db.Movies.Add(movie) and db.SaveChanges()
}

movie.Actors.Add(actor);
db.SaveChanges();
This should allow you to update the many to many table.