Controlling the Currency of Binded Controls

Controlling the Currency of Binded Controls

• hezkryvo

  this should help

  ms-help://MS.MSSDK.1033/MS.WinFXSDK.1033/wpf_conceptual/html/fcd37590-bce1-4ac9-8b74-3b96c7458b8a.htm

  
  
  

• Nands

  WOW....

  thank u guys very much....for ur help...

  but i have a problem in my code that DataContext returns a null when i call it

  here is my code:

  SqlConnection conn =

  new SqlConnection(@"Data Source=BIZCORE\BIZCORE2005;Initial Catalog=SismatixERP;Integrated Security=True");

  SqlDataAdapter adap =

  new SqlDataAdapter("select * from com_m_country", conn);

  ds = new DataSet();

  ds.Tables.Add(new DataTable("table1"));

  adap.Fill(ds, "table1");

  Binding bind = new Binding("NameEn");

  bind.Mode = BindingMode.TwoWay;

  bind.Source = ds.Tables[0];

  this.textBox2.SetBinding(TextBox.TextProperty, bind);

  in the previuos code i did the binding using code there no thin in the XAML file indecating that iam doing binding...

  but when i get the DataContext object either for the Form or for the TextBox object i used...i found DataContext Property is null....

  i realy find ur code is great but help me to use it...or tell me whats wrong with my code....or is there a missing code to fill the DataContext property...by the way i tried the following code but no result still null value:

  this.textBox2.DataContext = bind;

  so sorry for bothering but this is the case....

  
  
  

• Peter Smith

  Or you can just use the collectionview as the previous user suggested ;)
  
  

• T. Bolon

  Here is a way to do this.

  Create a custom collection class (maybe even generic)

  Add properties on the class that point to the "Current" object of the collection

  Add functions to the collection to move "Current" to first, previous, next, and last.

  Set the datacontext on your form to the Current property of your collection

  here is the code for the custom collection.

  using System;
  using System.Collections.Generic;
  using System.Collections.ObjectModel;
  using System.Text;
  using System.ComponentModel;
  
  namespace CursorCollectionSample
  {
  public class CursorCollection<T>:Collection<T>,INotifyPropertyChanged
  {
  public event PropertyChangedEventHandler PropertyChanged;
  
  #region Private Fields
  
  private int m_Current;
  
  #endregion
  
  #region Public Properties
  
  public T Current
  {
  get { return this[m_Current]; }
  set{this[m_Current] = value;}
  }
  
  #endregion
  
  public T GetNext()
  {
  T tmpCurrent;
  if (m_Current < Count - 1)
  {
  tmpCurrent = this[++m_Current];
  NotifyCurrentChanged();
  }
  else
  {
  tmpCurrent = this[m_Current];
  }
  return tmpCurrent;
  }
  
  public T GetPrevious()
  {
  T tmpCurrent;
  if (m_Current > 0)
  {
  tmpCurrent = this[--m_Current];
  NotifyCurrentChanged();
  }
  else
  {
  tmpCurrent= this[m_Current];
  }
  return tmpCurrent;
  }
  
  private void NotifyCurrentChanged()
  {
  if (PropertyChanged != null)
  {
  PropertyChanged(this, new PropertyChangedEventArgs("Current"));
  }
  }
  
  public void InsertAfter(T item)
  {
  if (m_Current == Count)
  {
  Add(item);
  }
  else
  {
  Insert(m_Current + 1, item);
  }
  }
  
  public void InsertBefore(T item)
  {
  Insert(m_Current, item);
  }
  }
  }

  I made it a generic class so that you can have type safety for any objects. To construct an instance

  CursorCollection<MyClass> myCollection=new CursorCollection<MyClass>();

  (Where MyClass is replaced with the class that will be inserted into the collection.)

  Your only remaining steps are to populate your collection with objects, bind your forms datacontext to your collection's Current property, and make your buttons call GetNext and GetPrevious.

  
  
  
• Controlling the Currency of Binded Controls