StudentDbContext is null using Asp.net Core Web api - asp.net-mvc

Question

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);
}
}

Answer 1

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.