spaghetti_code
spaghetti_code

Reputation: 145

Populating a listbox from database with Entity Framework

I'm developing a .NET application, and I have a problem. I try to populate a listbox from a MySQL database with Entity Framework. Here is my code:

public MainForm()
        {
            InitializeComponent();
            try
            {
                hospitaldbEntities context = new hospitaldbEntities();
                PatientlistBoxId.DataSource = context.patients;
                PatientlistBoxId.DisplayMember = "FirstName";
            }
            catch (Exception ex)
            {
                Console.WriteLine(ex);
            }
        }

I attach a picture from the Solution Explorer: enter image description here

And finally here is my patient class:

public partial class patient
    {
        public patient()
        {
            this.examinations = new HashSet<examination>();
            this.diseases = new HashSet<disease>();
            this.drugsensitivities = new HashSet<drugsensitivity>();
        }

        public int PatientID { get; set; }
        public string FirstName { get; set; }
        public string LastName { get; set; }
        public System.DateTime DateOfBirth { get; set; }
        public string Gender { get; set; }
        public string Address { get; set; }
        public System.DateTime DateOfCreate { get; set; }
        public string Category { get; set; }
        public int CNP { get; set; }

        public virtual ICollection<examination> examinations { get; set; }
        public virtual ICollection<disease> diseases { get; set; }
        public virtual ICollection<drugsensitivity> drugsensitivities { get; set; }
    }

Thank you for the help in advance.

EDIT

When I try to run the application, it throws an error: enter image description here

Upvotes: 2

Views: 3628

Answers (1)

tschmit
tschmit

Reputation: 7800

You must at least use:

PatientlistBoxId.DataSource = context.patients.ToList();

Consider using a BindingList<T>

BTW:

Consider not using an Entity type as ItemType for the ListBox.

Consider using a using context to dispose your context, that is handle more clearly the scope of your context.

========== ==========

A little bit more details

//this class allows to separate the winform (equivalent to a view) from 
//the data layer, you can see it as a ViewModel
public class FormNamePatient {
    public Int32 Id { get; set;}
    public String FirstName { get; set;}
    public String LastName { get; set;}
}

private BindingList<FormNamePatient> _patients;
try {
   //the using guarantees the disposing of the resources 
   //(avoiding memory link and so on)
   using ( hospitaldbEntities context = new hospitaldbEntities() ) {
       _patients = new BindindList<FormNamePatient>(
           context.patients.Select(
              x => new FormNamePatient {
                  Id = x.Id,
                  FirstName = x.FirstName,
                  LastName = x.LastName,
              }).ToList() // this materialize the list
                          // in other (bad ?) words, this allows the list
                          //to live out of the context (<=> using)
       );       
   }
   PatientlistBoxId.DataSource ) = _patients;
   //now if you alter (not erase, but edit, change...) _patients you 
   //update the control
   PatientlistBoxId.DisplayMember = "FirstName";
} catch (Exception ex) {
  Console.WriteLine(ex);
}

Upvotes: 1

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