c# - WPF combobox update other combobox based on selection of first one -

my wpf application has 2 comboboxes follows

<combobox height="23" name="projectnamecombobox" width="215" itemssource="{binding}" displaymemberpath="name" selectionchanged="projectselection_changed" />  <combobox height="25" name="langaugecombobox"  width="108" itemssource="{binding}" displaymemberpath="name"  /> 

and code behind binding using database as

projectnamecombobox.datacontext = dbconnector.getprojectnames(); langaugecombobox.datacontext = dbconnector.getlanguages(); 

project combobox contains list of projects

langauges combobox contains list of langauges.

i want updated langauges combobox based on project selection.

based on project selection able langauges project database, how set in langauge combobox.

langaugecombobox.selectedvalue = dt.rows[0][0].tostring(); not working.

and suggestion/help?

i advice start migrating events binding , change notifications. more wpf way.

so code 2 comboboxes become this, removed selectionchanged event handler , i'll remove name unless required

<combobox height="23" width="215" itemssource="{binding projects}" displaymemberpath="name" selecteditem="{binding selectedproject}" /> <combobox height="25" width="108" itemssource="{binding languages}" displaymemberpath="name" selecteditem="{binding selectedlanguage}" /> 

then (instead of) code behind class following properties, instance of class goes datacontext view

    public observablecollection<project> projects     {         { return (observablecollection<project>)getvalue(projectsproperty); }         set { setvalue(projectsproperty, value); }     }      // using dependencyproperty backing store projects.  enables animation, styling, binding, etc...     public static readonly dependencyproperty projectsproperty =         dependencyproperty.register("projects", typeof(observablecollection<project>), typeof(viewmodel), new propertymetadata(null));      public observablecollection<language> languages     {         { return (observablecollection<language>)getvalue(languagesproperty); }         set { setvalue(languagesproperty, value); }     }      // using dependencyproperty backing store languages.  enables animation, styling, binding, etc...     public static readonly dependencyproperty languagesproperty =         dependencyproperty.register("languages", typeof(observablecollection<language>), typeof(viewmodel), new propertymetadata(null));      public project selectedproject     {         { return (project)getvalue(selectedprojectproperty); }         set { setvalue(selectedprojectproperty, value); }     }      // using dependencyproperty backing store selectedproject.  enables animation, styling, binding, etc...     public static readonly dependencyproperty selectedprojectproperty =         dependencyproperty.register("selectedproject", typeof(project), typeof(viewmodel), new propertymetadata(null, onselectedprojectchanged));      public language selectedlanguage     {         { return (language)getvalue(selectedlanguageproperty); }         set { setvalue(selectedlanguageproperty, value); }     }      // using dependencyproperty backing store selectedlanguage.  enables animation, styling, binding, etc...     public static readonly dependencyproperty selectedlanguageproperty =         dependencyproperty.register("selectedlanguage", typeof(language), typeof(viewmodel), new propertymetadata(null)); 

then property change handler

    private static void onselectedprojectchanged(dependencyobject d, dependencypropertychangedeventargs e)     {         view v = d view;         v.selectedlanguage = //your logic here eg. v.selectedproject.language;     } 

so binding in place language combo box update selected item based on value set selectedlanguage.