EF Core 一对多关系实例化 Object 内部 Object 构造函数

Question

I am very new to C# and EF Core. I have the following entity classes: One Doctor has many Patients. I am trying to create/post a new patient in Postman, and the Doctor property is required. When I create a patient and pass a DoctorId to be used for instantiating a patient, is there a way to get the DoctorId that is being passed to also instantiate the Doctor property (object) within the constructor at the same time? Basically, I need to save the existing instance of the Doctor using the DoctorId being passed in to create a patient as well. Is there a way to do this?

I need this piece of code (in Patient.cs) to tell Entity Framework that Doctor and Patient has one to many relationship when I add migration.

public Doctor Doctor { get; set; } = new Doctor();

Here are the model classes:

Doctor.cs:

public class Doctor : IdentityUser
{
    public string FirstName { get; set; }
    public string LastName { get; set; }
    public ICollection<Patient>? Patients { get; set; }

    public Doctor()
    {

    }

    public Doctor(string firstName, string lastName, ICollection<Patient>? patients)
    {
        FirstName = firstName;
        LastName = lastName;
        Patients = patients;
    }
}

Patient.cs

public class Patient
{
    public int PatientId { get; set; }
    public string FirstName { get; set; }
    public string LastName { get; set; }
    public DateTime DateOfBirth { get; set; }
    public int Age => this.CalculateAge(DateOfBirth);
    public Gender Gender { get; set; }
    public string DoctorId { get; set; }
    public Doctor Doctor { get; set; }
    public ICollection<Diagnosis>? Diagnoses { get; set; }
    
    //Get doctor id being passed and save it as doctor object

    public Patient()
    {
    }

    public Patient(int patientId, string firstName, string lastName, DateTime dateOfBirth, Gender gender, Doctor doctor, string doctorId, ICollection<Diagnosis>? diagnoses)
    {
        PatientId = patientId;
        FirstName = firstName;
        LastName = lastName;
        DateOfBirth = dateOfBirth;
        Gender = gender;
        Doctor = doctor;
        DoctorId = doctorId;
        Diagnoses = diagnoses;
    }

Answer 1

What if you inject the context and just query the db with that id? im sure this helps you:) https://docs.microsoft.com/en-us/ef/core/modeling/constructors