Getting value and putting value to combobox

Question

I'm newbie with winforms and I'm using a combobox. I like to learn how to load from Database to Controls (Combobox) and how to SAVE values from Control (combobox) to Database field.

Below I need some help on process get from Combobox and put/select value to combobox... But don't know how to do...

Below I get all rows in a list and bind to a combobox. That works fine, but like to do some actions which I'm struggling.

Can someone advice how to do these action?

1. I'd like to "add on top" of comboboxList an empty value so they can also select an empty value in comboboxlist.

2. How to select a value in combobox when putting from DB to Control.. I'm doing like this comboboxAccount.SeletedText = _account.Number, but it's not selecting.

3. now it's showing "Number" in combobox, but I like to show Number + "-" Description. How to do this? now it's showin e.g. 4000 but I like to show "4000 - Description1"

4. I like to store the Account.Id into the Database not the Account.Number, but how can I do that because the combobox is showing the Number... so SelectedText is not which I want.

Code:

public class Account
{
    public Int32 Id { get; set; }             e.g. 1
    public string Number{ get; set; }         e.g. 4000 (alpha-numeric)
    public string Description1 { get; set; }  e.g. Customer
    public string Description2 {get; set;}    e.g. VAT account
    public string Language {get; set;}        e.g. EN 
}

  //returns all rows
  IList<Account> _account = new List<Account>(Account_repository.GetAll());
  comboboxAccount.DataSource = account;
  comboboxAccount.DisplayMember = "Number";
  comboboxAccount.Add(??); (see point 1)

  //saving to database
  Client _client = new Client();
  _client.Account = comboboxAccount.??; (see point 4)

Answer 1

1) I'd like to "add on top" of comboboxList an empty value so they can also select an empty value in comboboxlist.

An item can never be added directly to the comobbox items, if the DataSource property is set. So, the list(datasource) should be updated with empyt/dummy object before setting it as the DataSource. You might have to find a way to describe that your current object is a dummy object.

Example, you could introduce an EmptyItem property, and handle/filter it before saving:

    public class Account
    {
        public Account(bool isEmptyItem =false)
        {
            this.EmptyItem = isEmptyItem;
        }

        public Int32 Id { get; set; }
        public string Number { get; set; }
        public string Description1 { get; set; }
        public string Description2 { get; set; }
        public string Language { get; set; }

        public bool EmptyItem { get; private set; } 
    }

   IList<Account> _account = new List<Account>();
   _account.Add(new Account(true))
   _account.AddRange(Account_repository.GetAll());

.

2) *How to select a value in combobox when putting from DB to Control..I'm doing like this comboboxAccount.SeletedText = _account.Number, but it's not selecting.*

Since the comboBox is binded to an object, you cannot set its SelectedText instead you should use SelectedItem

Example://You need to write a logic to find out how to get this item.

this.comboboxAccount.SelectedItem = this.comboboxAccount.Items[1];

3) now it's showing "Number" in combobox, but I like to show Number + "-" Description. How to do this? now it's showin e.g. 4000 but I like to show "4000 - Description1"

You might have to expose another propety say DisplayText and bind it to DisplayMember of the combobox.

Example:

public class Account
{
    public string Number { get; set; }
    public string Description1 { get; set; }

    public bool EmptyItem { get; private set; }

    public string DisplayText
    {
        get{return this.Number + "-" + this.Description1}
    }
}

this.comboboxAccount.DisplayMember = "DisplayText";

4) I like to store the Account.Id into the Database not the Account.Number, but how can I do that because the combobox is showing the Number... so SelectedText is not which I want.

You should use SelectedItem since you have binded an object

var account = this.comboboxAccount.SelectedItem as Account;

var accountID = account.Id;

Answer 2

First, I think you shoul use something like a Dictionary or List> or DataTable.

1) You should insert your empty value in your List and then bind it to your combobox

    _account.Insert(0, "Empty");

2) Define your ValueMember also(you shoul have a List or a DataTable):

If you have a DataTabele:

    comboboxAccount.ValueMember = "columnID";
    comboboxAccount.DisplayMember = "columnValue";
    comboboxAccount.DataSource = yourDataTable;
    combobox.SelectedIndex = 0; //your empty value

3) You should create another property in your class and use this as DisplayMember;

    string NumberDescription{ get; set; };
    comboboxAccount.DisplayMember = "NumberDescription";

4) If you want to store the ID of the selected value you should use your previously defined ValueMember(the column ID):

    int value = Convert.ToInt32(cbomboboxAccount.SelectedValue);

    // if you want to save the text of the value selected in the combobox:
    string strValue = comboboxAccount.Text;