Show Foreign Key json object in http GET EntityFramework

Question

I'm currently learning ASP.NET and having some problems. I have 2 tables related to each other by Foreign Key.
Employee.cs

public class Employee
    {
        [Key]
        public int EmployeeId { get; set; }
        [Column(TypeName = "nvarchar(50)")]
        [Required]
        public string EmployeeFullName { get; set; }
        [Required]
        [ForeignKey("DepartmentId")]
        public virtual Department EmployeeDepartment { get; set; }
    }

Department.cs

public class Department
    {
        [Key]
        public int DepartmentId { get; set; }
        [Column(TypeName = "nvarchar(10)")]
        [Required]
        public string DepartmentName { get; set; }
    }

I use the HTTP POST JSON and normally get values at both tables:

{
  "employeeId": 0,
  "employeeFullName": "string",
  "employeeDepartment": {
    "departmentId": 0,
    "departmentName": "string"
  }
}

But when I use the GET HTTP. I got:

[
  {
    "employeeId": 1,
    "employeeFullName": "string",
    "employeeDepartment": null
  }
]

How can I show the employeeDepartment as JSON instead. Like this:

[
  {
    "employeeId": 1,
    "employeeFullName": "string",
    "employeeDepartment":{
    "departmentId":1,
    "departmentName":"string"
    }
  }
]

I use the API Controller

[HttpGet("{id}")]
        public async Task<ActionResult<Employee>> GetEmployee(int id)
        {
            var employee = await _context.Employees.FindAsync(id);

            if (employee == null)
            {
                return NotFound();
            }

            return employee;
        }

How can I use http GET to receive just some specific fields? For example, I just want to get the EmployeeId with EmployeeFullName only.

Serge · Accepted Answer · 2021-08-12 18:00:43Z

1

Try this

public async Task<ActionResult<Employee>> GetEmployee(int id)
 {
 
var employee = await _context.Employees
             .Include(i=> i.EmployeeDepartment)
             .Where(i=> i.EmployeeId == id)
             .FirstOrDefaultAsync();

            if (employee == null)
            {
                return NotFound();
            }

            return Ok(employee);
        }

UPDATE

if you want to get just employee name try this

public async Task<ActionResult<string>> GetEmployee(int id)
 {

var employeeName = await _context.Employees
             .Where(i=> i.EmployeeId == id)
             .Select (i=> i.EmployeeFullName)
             .FirstOrDefaultAsync();

            if (employeeName == null)
            {
                return NotFound();
            }

            return Ok( employeeName);
}

or

public async Task<ActionResult> GetEmployee(int id)
 {

var employeeName = await _context.Employees
        .Where(i=> i.EmployeeId == id)
      .Select (i=>  new { EmployeeFullName= i.EmployeeFullName})
      .FirstOrDefaultAsync();
.....
 
// or maybe if you want it inside of array
public async Task<ActionResult<IEnumerable<Employee>>> GetEmployee(int id)
 {

var employeeName = await _context.Employees
        .Where(i=> i.EmployeeId == id)
       .Select (i=>  new Employee {
 EmployeeId=  i.EmployeeId,
 EmployeeFullName=  i.EmployeeFullName})
             .ToArrayAsync();

var employeeName = await _context.Employees
        .Where(i=> i.EmployeeId == id)
       .Select (i=>  new {
 EmployeeId=  i.EmployeeId,
 EmployeeFullName=  i.EmployeeFullName})
             .ToArrayAsync();

or maybe if you want an array of all employees

public async Task<ActionResult> GetAll()
 {
var employeeNames = await _context.Employees
   .Select (i=>  new Employee { 
  EmployeeId=  i.EmployeeId,
 EmployeeFullName=  i.EmployeeFullName})
             .ToArrayAsync();

//or just array of all employee names
var employeeNames = await _context.Employees
        .Select (i=> i.EmployeeFullName)
             .ToArrayAsync();

you can try all of them and select what you need

edited Aug 12, 2021 at 18:00

answered Aug 12, 2021 at 16:16

Serge

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7 Comments

Đạt Nguyễn Over a year ago

Thanks! It works! Can I ask one another question? How can I show some specific fields only in http GET, like I want to post all the fields, but only get employeeFullName only for example. I'll update the question.

Serge Over a year ago

@ĐạtNguyễn I updated my answer pls check and let me know if it is what you want or I can make changes

Đạt Nguyễn Over a year ago

Can I get it as an object? Like this: [ {"employeeFullName":"string"} ]

Serge Over a year ago

where do you have this error ? inside of the action? and what query have you selected? try Task<ActionResult<IEnumerable<Employee>>> or Task<ActionResult<Employee>> one of them should work

Serge Over a year ago

@ĐạtNguyễn And try to use return Ok(employee) or Ok(employeeName);

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