data binding - WPF Dependency Property Question -

i'm new wpf, , i'm trying thought simple task - display value of field in business object changes during program. know how "force" change manually changing textbox.text property in c#, i'm learning wpf want "right" way, , means databinding.

question #1: far understand it, choice either use dependencyproperty or implement inotifypropertychanged in business object, right?

question #2: here generic version of code in attempted go dependencyproperty route.

markup:

button x:name="nextbutton" content="click"  grid.row="2" click="nextbutton_click" /> textbox x:name="mytextbox" grid.row="1" text="{binding source=mytest, path=name, updatesourcetrigger=propertychanged, notifyonsourceupdated=true}"/>

code-behind:

namespace dependencytest2 {     ///      /// interaction logic mainwindow.xaml     ///      public partial class mainwindow : window     {         private int i;          private testsphere mytest;          public mainwindow()         {             initializecomponent();              = 0;              mytest = new testsphere();         }          private void nextbutton_click(object sender, routedeventargs e)         {             switch (i)             {                 case 0:                     mytest.name = "string1";                     break;                 case 1:                     mytest.name = "string2";                     break;                 case 2:                     mytest.name = "string3";                     break;             }              i++;         }     }      class testsphere : dependencyobject     {          public string name         {             { return (string)getvalue(nameproperty); }             set { setvalue(nameproperty, value); }         }          public static readonly dependencyproperty nameproperty =             dependencyproperty.register("name", typeof(string), typeof(testsphere));           public testsphere()         {             name = "default";         }     } } 

when run program, nothing appears in text box, though bound property has value - there else need alert binding source value has changed? thought using dependencyproperty source take care of that, again, i'm wpf rookie. thanks!

• steve

ok, tried implement inotifypropertychanged using wrapper class found on codeproject follows:

     class testsphere : notifyproperychangedbase     {         private string _name;          public string name         {             { return _name; }             set              {                 this.checkpropertychanged("name", ref _name, ref value);             }         }          public testsphere()         {             name = "default";         }     }      public abstract class notifyproperychangedbase : inotifypropertychanged     {         #region inotifypropertychanged members         public event propertychangedeventhandler propertychanged;         #endregion         #region methods         protected bool checkpropertychanged(string propertyname, ref t oldvalue, ref t newvalue)         {             if (oldvalue == null && newvalue == null)             {                 return false;             }              if ((oldvalue == null && newvalue != null) || !oldvalue.equals((t)newvalue))             {                 oldvalue = newvalue;                 firepropertychanged(propertyname);                 return true;             }              return false;         }          protected void firepropertychanged(string propertyname)         {             if (this.propertychanged != null)             {                 this.propertychanged(this, new propertychangedeventargs(propertyname));             }         }          #endregion 

here new markup, too:

     grid name="mygrid">         grid.rowdefinitions>             rowdefinition height="30"/>             rowdefinition height="30"/>             rowdefinition height="30"/>             rowdefinition height="*"/>         /grid.rowdefinitions>         label x:name="mylabel" grid.row="0" foreground="black"  />         button x:name="nextbutton" content="click"  grid.row="2" click="nextbutton_click" />         textbox x:name="mytextbox" grid.row="1" text="{binding path=mytest.name}"/>     /grid> 

i added line mygrid.datacontext = mytest; 'public mainwindow()' after instantiate mytest. when step through resulting program, value of this.propertychanged evaluates null, propertychanged never fires. sorry in advance must noob question.

• steve

you should need implement inotifypropertychanged on testsphere class, not dependencyobject. update value, call propertychanged(this, new propertychangedeventargs("name")).

second, need set datacontext window in code-behind. lets used in xaml root grid element:

<grid name="mainform"> 

then in code-behind, you'd this:

mainform.datacontext = this; 

finally, change mytest property public, , binding in xaml should need be

text="{binding path=mytest.name}"