Category Table ;
public int CategoryId{ get; set; }
public string Name{ get; set; }
public List<ProductCategory> ProductCategories { get; set; }
I add new field to the table;
public int CategoryId{ get; set; }
public string Name{ get; set; }
public List<ProductCategory> ProductCategories { get; set; }
public string Url{ get; set; }
I get the following error when updating entity;
Microsoft.EntityFrameworkCore.DbUpdateException: 'An error occurred while updating the entries. See the inner exception for details.'
eShopContext;
public DbSet<Product> Products{ get; set; }
public DbSet<Category> Categories{ get; set; }
public object Configuration { get; internal set; }
protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
{
optionsBuilder.UseSqlServer(
#"Server=gdagad;Database=eStoreAppDB;Trusted_Connection=True;");
}
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
base.OnModelCreating(modelBuilder);
modelBuilder.Entity<ProductCategory>()
.HasKey(c => new {c.CategoryId, c.ProductId});
}
}
SeedDatabase.cs;
Use the EF Core Migrations feature to update the database.
1. Add-Migration AddUrl
2. Update-Database
add a new field to an ASP.NET Core MVC app
Related
I'm creating a CRUD project in asp.net entity framework, and from my understanding, in order to see the data on the HTML page I have to scaffold the pages. For example I have two entity models Student and Major
This is the Student entity
public class Student
{
public int Id { get; set; }
public string Name { get; set; }
[ForeignKey("Major")]
public int? MajorId { get; set; }
public Major Major { get; set; }
[ForeignKey("Advisor")]
public int AdvisorId { get; set; }
public Advisor Advisor { get; set; }
public ICollection<StudentCourses>? StudentCourses { get; set; }
}
This is the Major entity
public class Major
{
public int MajorId { get; set; }
public string MajorName { get; set; }
public ICollection<Student> Students { get; set; }
public ICollection<Advisor> Advisors { get; set; }
public ICollection<MajorCourse> MajorCourses { get; set; }
}
If I want to see the Student data I have to create a Students folder and add a new Scaffolding along with a DbContext like your_namespace.Data.StudentContext. I would also have to follow the same steps for the Major entity but am I correct to use another DbContext? For example: your_namespace.Data.MajorContext. This is what I have done but when I try to make migrations and update the database in the your_namespace.Data.MajorContext, I get an error that reads SQLite Error 1: 'table "StudentCourses" already exists'.`
How do I fix this error?
I should also add the Context classes:
This is the StudentContext class:
public class AdvismentContext : DbContext
{
public AdvismentContext(DbContextOptions<AdvismentContext> options)
: base(options)
{
}
public DbSet<Student> Students { get; set; }
public DbSet<Major> Majors { get; set; }
public DbSet<Advisor> Advisors { get; set; }
public DbSet<Course> Courses { get; set; }
public DbSet<MajorCourse> MajorCourses { get; set; }
public DbSet <StudentCourses> StudentCourses{ get; set; }
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
modelBuilder.Entity<Student>()
.ToTable("Students");
modelBuilder.Entity<Major>()
.ToTable("Majors");
modelBuilder.Entity<Advisor>()
.ToTable("Advisors");
modelBuilder.Entity<Course>()
.ToTable("Courses");
//modelBuilder.Entity<MajorCourse>()
// .ToTable("MajorCourse");
//.HasKey(mc => new { mc.MajorId, mc.CourseId });
}
And this is the MajorContext class:
public class MajorContext : DbContext
{
public MajorContext (DbContextOptions<MajorContext> options)
: base(options)
{
}
public DbSet<Advisment.Models.Major> Major { get; set; } = default!;
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
modelBuilder.Entity<Major>()
.ToTable("Major");
//modelBuilder.Entity<MajorCourse>() This is commented out because I was getting the same error that the table already exists.
// .ToTable("MajorCourse");
}
}
What am I doing wrong?
I am trying to create a Product table that will have a list of SubstitutionProducts that should reference other Product from the same table.
Model example :
public class Product
{
public int Id { get; set; }
public string Name { get; set; }
public bool IsMissing { get; set; }
public ICollection<Product> SubstitutionProducts { get; set; }
}
It is better to include the parent ID in your model:
public class Product
{
public int Id { get; set; }
public string Name { get; set; }
public bool IsMissing { get; set; }
public int? ParentId { get; set; }
public Product Parent { get; set; }
public ICollection<Product> SubStitutionProducts { get; set; }
}
This is how to configure DB schema via overriding OnModelCreatingmethod of your DbContext:
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
modelBuilder.Entity<Product>().HasOne(x => x.Parent)
.WithMany(x => x.SubStitutionProducts)
.HasForeignKey(x => x.ParentId).IsRequired(false);
}
I am using VS2017. since the last upgrade I have not been able to create migration scripts.
This is my context class:
public class MyDBContext : DbContext
{
public MyDBContext(
DbContextOptions<MyDBContext> options ) : base( options )
{
}
public DbSet<Address> Addresses { get; set; }
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
base.OnModelCreating(modelBuilder);
modelBuilder.Entity<Address>().ToTable("Address");
}
}
public class Address
{
public Int64 AddressId { get; set; }
public string AddressRef { get; set; }
public string Address1 { get; set; }
public string Address2 { get; set; }
public string Address3 { get; set; }
public string Town { get; set; }
public string PostCode { get; set; }
public string County { get; set; }
public string Country { get; set; }
public DateTime? ServerTs { get; set; }
public string ServerRef { get; set; }
public bool Active { get; set; }
public string AccountRef { get; set; }
public string CustomerRef { get; set; }
}
protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
{
optionsBuilder.UseSqlServer("Server=localhost;Initial Catalog=MyDB;Integrated Security=True;MultipleActiveResultSets=true");
}
I go to 'Package Manager Console'.
I set the default project to this project.
I type in 'Add-Migration InitialCreate'
It 'runs'
Then finishes without any errors. Yet, the Migrations folder is not created.
Have I missed a step out and cannot remember and upgrading to the latest version of VS2017 is just a coincidence?
Thanks
EF.core beginner here.
In my app I have Persons. These are connected to other persons (in that same table), and those connections have a 'level'. I've added a join table called connection to store who is connected to who and on what level. When trying to do an Add-migration i get the following error:
Unable to determine the relationship represented by navigation property 'Connection.Person' of type 'Person'. Either manually configure the relationship, or ignore this property from the model.
There is no problem on my other join tables that reference two different tables. What am i missing here?
I'm using EF.core 1.1, with .net 4.5, code below
public class Person
{
public int Id { get; set; }
public string Name { get; set; }
public string NickName { get; set; }
public List<Connection> Connections { get; set; }
}
public class Connection
{
public int PersonId { get; set; }
public Person Person { get; set; }
public int SecondPersonId { get; set; }
public Person SecondPerson { get; set; }
public int ConnectionLevelId { get; set; } // connection Level
public ConnectionLevel Level { get; set; }
}
public class ConnectionLevel
{
public int Id { get; set; }
public string Name { get; set; }
//rights
}
public class testContext : DbContext
{
public DbSet<Person> Persons { get; set; }
public DbSet<Connection> Connections { get; set; }
public DbSet<ConnectionLevel> ConnectionLevels { get; set; }
protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
{
optionsBuilder.UseSqlServer("Server=localhost\\SQLEXPRESS;Database=master;Trusted_Connection=True;");
base.OnConfiguring(optionsBuilder);
}
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
modelBuilder.Entity<Connection>().HasKey(s => new { s.PersonId, s.SecondPersonId });
base.OnModelCreating(modelBuilder);
}
}
I'm trying to code first on asp.net membership provider. When code first creates the table, it generates all tables and appropriate relationship to the bridge table but it also create an additional relationship from the AspNet_User(one) to Aspnet_Role(many). Do you know why it doing this? There shouldn't be any relationship between user and role table.
public class Aspnet_Role
{
public Aspnet_Role()
{
Aspnet_Users = new HashSet<Aspnet_Users>();
}
[Key]
public Guid RoleId { get; set; }
public string RoleName { get; set; }
public string LoweredRoleName { get; set; }
public string Description { get; set; }
public virtual ICollection<Aspnet_Users> Aspnet_Users { get; set; }
}
public class Aspnet_Users
{
public Aspnet_Users()
{
Aspnet_Roles = new HashSet<Aspnet_Role>();
}
[Key]
public Guid UserId { get; set; }
public string UserName { get; set; }
public string LoweredUserName { get; set; }
public string MobileAlias { get; set; }
public bool IsAnonymous { get; set; }
public DateTime LastActivityDate { get; set; }
public virtual Aspnet_Membership Aspnet_Membership { get; set; }
public virtual ICollection<Aspnet_Role> Aspnet_Roles { get; set; }
}
public class StagingContext : DbContext
{
public DbSet<Aspnet_Role> Aspnet_Roles { get; set; }
public DbSet<Aspnet_Users> Aspnet_Users { get; set; }
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
base.OnModelCreating(modelBuilder);
modelBuilder.Entity<Aspnet_Users>()
.HasMany(r => r.Aspnet_Roles)
.WithMany()
.Map(m => m.ToTable("aspnet_UsersInRoles")
.MapRightKey("RoleId")
.MapLeftKey("UserId"));
}
}
I added the navigation property on the WithMany extension.
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
base.OnModelCreating(modelBuilder);
modelBuilder.Entity<Aspnet_Users>()
.HasMany(r => r.Aspnet_Roles)
.WithMany(u => u.Aspnet_Users)
.Map(m => m.ToTable("aspnet_UsersInRoles")
.MapRightKey("RoleId")
.MapLeftKey("UserId"));
}