I using "Entity Framework DbContext" at the moment I have got exception towars.dbo was not found. This is very strange because in my website I all the time ask about towar.dbo but no towars.dbo Do you know where is a problem?
- InnerException {"Invalid object name 'dbo.Towars'."} System.Exception {System.Data.SqlClient.SqlException}
My all things about Towar (of course different place in my program):
public class ProductController : Controller
{
//
// GET: /Product/
public ITowarRepository repository;
public ProductController(ITowarRepository productRepository)
{
repository = productRepository;
}
public ViewResult List()
{
return View(repository.Towar);
}
}
public interface ITowarRepository
{
IQueryable<Towar> Towar { get; }
}
public DbSet<Towar> Towar { get; set; }
public class EFTowarRepository : ITowarRepository
{
public EFDbContext context = new EFDbContext();
public IQueryable<Towar> Towar
{
get { return context.Towar; }
}
}
public class Towar
{
[Key]
public int Id_tow { get; set; }
public string Nazwa { get; set; }
public string Opis { get; set; }
public decimal Cena { get; set; }
public int Id_kat { get; set; }
}
Add the following line to your context:
modelBuilder.Conventions.Remove<PluralizingTableNameConvention>();
You can tell EF to map to the table Towar by overriding the OnModelCreating method in your DBContext class with fluent API like this:
public class EFDbContext : DbContext
{
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
modelBuilder.Entity<Towar>().ToTable("Towar");
}
}
Now EF will look for Towar table instead of Towars. If you do not have these tables created, there is some other problem you are having.
EF Code First automatically pluralizes the table names. Use a [Table] attribute to explicitly map the entity to a table name:
[Table("Towary")]
public class Towary
{
// Whatever properties
}
It looks like there's a way to disable pluralization gobally too, see Entity Framework Code First naming conventions - back to plural table names?.
using System.Data.Entity.ModelConfiguration.Conventions;
namespace MVCDemo.Models
{
public class EmployeeContext : DbContext
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
modelBuilder.Conventions.Remove<PluralizingTableNameConvention>();
}
}
For the sake of completeness #forty-two
Related
am a beginner in ASP.NET Core. I am creating a Web API service. While I am fetching the data from the database, I had a problem. What is the error I got? I have successfully done the database migration part and created the database successfully.
StudentDbContext is null
StudentController
namespace webb.Controllers
{
[Route("api/[controller]")]
[ApiController]
public class StudentController : ControllerBase
{
private StudentDbContext studentDbContext;
public StudentController(StudentDbContext studentDbContext)
{
studentDbContext = studentDbContext;
}
// GET: api/<EmployeeController>
[HttpGet]
public IEnumerable<Student> Get()
{
// var studens = studentDbContext.Student;
return studentDbContext.Student;
}
}
}
Model
public class Student
{
public int id { get; set; }
public string stname { get; set; }
public string course { get; set; }
}
}
StudentDbContext
public class StudentDbContext : DbContext
{
public StudentDbContext(DbContextOptions<StudentDbContext> options) : base(options)
{
}
public DbSet<Student> Student { get; set; }
protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
{
optionsBuilder.UseSqlServer("Data Source=.;Initial Catalog=ams;Integrated Security=True; TrustServerCertificate = True");
}
}
IDataService
public interface IDataService<T>
{
Task<IEnumerable<T>> GetAll();
Task<T> Get(int id);
Task<T> Create(T entity);
Task<bool> Delete(T entity);
Task<T> Update(T entity);
}
}
I have successfully done the database migration part and created the
database successfully. StudentDbContext is null
Well, two mistake has been done. Your model has no primary key. So you will always get null data when there is no primary key set to your table column.
Therefore, your model should be as following:
Model:
public class Student
{
[Key]
public int id { get; set; }
public string stname { get; set; }
public string course { get; set; }
}
Controller:
Another misake is here studentDbContext.Student; this will not bring anything. You would be liking to fetch student list instead. So you should write studentDbContext.Student.ToList();. As following"
[HttpGet]
public IEnumerable<Student> Get()
{
// var studens = studentDbContext.Student;
return studentDbContext.Student.ToList();
}
Note: In addition, your constructor convension is not correct, it can be written as following:
[Route("api/[controller]")]
[ApiController]
public class StudentController : ControllerBase
{
private readonly StudentDbContext _studentDbContext;
public StudentController(ApplicationDbContext studentDbContext)
{
_studentDbContext = studentDbContext;
}
// GET: api/<EmployeeController>
[HttpGet]
public IEnumerable<Student> Get()
{
// var studens = studentDbContext.Student;
return _studentDbContext.Student.ToList();
}
}
Note: You can check more details on asp.net core web api official document here
Output:
For further details you can have a look on official document here.
I keep falling into the trap of declaring an abstract base class for my tables and then finding that the base class is created by the data migration.
I know not to create a DBSet in the context for the table I don't want
The following class does not cause a BasicBo table to create
public abstract class BasicBo : IXafEntityObject //, IObjectSpaceLink we should just declare it when we really need it... mainly we want out business objects to be like POCOs
{
[Browsable(false)]
[Key]
public virtual int Id { get; set; }
public virtual void OnCreated()
{
}
public virtual void OnSaving()
{
}
public virtual void OnLoaded()
{
}
}
However this class does cause a BasicNodeBo table to be created
public abstract class BasicNodeBo : IXafEntityObject
{
[Browsable(false)]
[Key]
public virtual int Id { get; set; }
public virtual int SiblingOrder { get; set; }
public virtual string Sequence { get; set; }
public virtual void RecalculateSequence()
{
}
public virtual void AddDependency(IObjectSpace os, BasicNodeBo sibling)
{
}
public virtual void OnCreated()
{
}
public virtual void OnSaving()
{
}
public virtual void OnLoaded()
{
}
}
I think it may be the presence of BasicNodeBo as a persistant navigation property in a business object..
I have view in SQL called ViewTest.
In code I have this model
[Table("dbo.ViewTest")]
public class ViewTest
{
public int Id { get; set; }
public int EmployeeID { get; set; }
public string PreferredName { get; set; }
public string EmailPrimaryWork { get; set; }
public string GeoCoverage { get; set; }
public string Role { get; set; }
public bool? LeftEmpFlag { get; set; }
}
In configuration file:
public virtual IDbSet<ViewTest> ViewTests { get; set; }
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
modelBuilder.Configurations.Add(new ViewConfiguration());
}
public class ViewConfiguration : EntityTypeConfiguration<ViewTest>
{
public ViewConfiguration()
{
this.HasKey(t => t.Id);
this.ToTable("ViewTest");
}
}
I want to have connection like this one ViewTests.Where(....) ,but when I tried to do like this way I have error There is already an object named 'ViewTest' in the database..This means entity framework try to create new Table and I don`t want this.I want to access this view only!
Well, it is code first so you should probably create your view in code. If that is not possible, then you need to tell EF not to create the table by commenting that line out of the Up() method on the migration. Once you update-database EF will have it in the metadata and you should be good to go.
I create a project in MVC 5 with entity framework 6. I am using code first approach. I want in one of the models define a different name for the table then the default. For that I use the System.ComponentModel.DataAnnotationsname space and define the class like this:
[Table(Name="Auditoria")]
public class AuditoriaDAL
{
[Key]
public int AuditoriaId { get; set; }
...
}
Running the project I get a database with a table with the name AuditoriaDALs. Why the table have this name a not the name that I define?
You are referencing the System.Data.Linq.Mapping.Table attribute when you need to reference System.ComponentModel.DataAnnotations.Schema.Table. So either do this:
[System.ComponentModel.DataAnnotations.Schema.Table("Auditoria")]
public class AuditoriaDAL
{
[Key]
public int AuditoriaId { get; set; }
...
}
Or better yet:
using System.ComponentModel.DataAnnotations.Schema;
...
[Table("Auditoria")]
public class AuditoriaDAL
{
[Key]
public int AuditoriaId { get; set; }
...
}
https://msdn.microsoft.com/en-us/library/system.componentmodel.dataannotations(v=vs.110).aspx
you can set TableName like below :
public class MyContext : DBContext
{
public virtual DbSet<AuditoriaDAL> Auditorias { get; set; }
}
Or in OnModelCreating :
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
base.OnModelCreating(modelBuilder);
modelBuilder.Entity<AuditoriaDAL>().ToTable("Auditorias");
}
The name= isn't necessary. You should try [Table("Auditoria")].
I want an object to reference itself. How do I write this model? For eg.
public class Term
{
public int TermId { get; set; }
public string Name { get; set; }
public virtual Term PreviousTerm { get; set; }
public virtual int? PreviousTermId { get; set; }
}
The schema generated is:
TermId
Name
PreviousTermId
PreviousTerm_TermId
So apparently, PreviousTermId serves no purpose here as a relationship FK.
But when using automapper, I have to map to PreviousTermId, I cant create the new object PreviousTerm and assign the Id to that. How do I fix this?
Try specifying the mappings in onModel OnModelCreating event
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
modelBuilder.Entity<Term>().HasOptional(t =>t.PreviousTerm).WithMany().
HasForeignKey(t=>t.PreviousTermId);
}