Need to create an API on the basis of ForeignKey in dotnet core - .net-core

Question

Here is my Schema and with two Foreign Key in an intermediate table. I am beginner in Core dotnet so unable to crate API to show the department in the school.
public class DepartmentSchool
{
public int Id { get; set; }
public int DepartmentID { get; set; }
[ForeignKey("DepartmentID")]
public virtual Department Department{ get; set; }
public int SchoolsId { get; set; }
[ForeignKey("SchoolsId")]
public virtual Schools Schools { get; set; }
Here I want to get all department related to school id, how can i get all the department though the School id in dotnetcore API.
Here is the school class entity schema.
public partial class Schools
{
public int ID { get; set; }
public string UicCode { get; set; }
public int SchoolSystemsId { get; set; }
public string BannerUrl { get; set; }
public string Name { get; set; }
public string Description { get; set; }
public string ImageUrl { get; set; }
public int UserID { get; set; }
public int? Status { get; set; }
public DateTime? CreatedAt { get; set; }
public int? CreatedBy { get; set; }
public DateTime UpdatedAt { get; set; }
public int? ModifiedBy { get; set; }
[ForeignKey("SchoolSystemsId")]
public PrivateSchoolSystem PrivateSchoolSystems { get; set; }
And more here is the department schema.
public partial class Department
{
public int Id { get; set; }
public string Title { get; set; }
public DateTime CreatedAt { get; set; }
public DateTime UpdatedAt { get; set; }
public int CreatedBy { get; set; }
public int UpdatedBy { get; set; }
public int SchoolSystemsID { get; set; }
[ForeignKey("SchoolSystemsID")]
public virtual PrivateSchoolSystem PrivateSchoolSystems { get; set; }
And I am trying to get a department list in the query in the following controller.
[Route("api/[controller]")]
[ApiController]
public class DepartmentSchoolController : ControllerBase
{
private readonly learning_gpsContext _learning_GpsContext;
public DepartmentSchoolController(learning_gpsContext learning_GpsContext)
{
_learning_GpsContext = learning_GpsContext;
}

Answer 1

[HttpGet("school/{schoolId}/departments")]
public IActionResult GetDepartmentsFromSchool(int schoolId)
{
var school = _learning_GpsContext.Schools.Where(e=>e.Id == schoolId).FirstOrDefault();
if (school == null)
return NotFound();
var departments = _learning_GpsContext.DepartmentSchool
.Where(e=>e.SchoolsId == schoolId).Select(e=>e.Department);
return Ok(departments);
}
For further learning check this tutorial. You should also understand what REST is and for basic questions always take a look at the official documenation.