ContentControl with DataTemplateSelector - help needed

Question

I got an enoying problem... Maybe someone can (please!) help. I am using a model that has and enumeration of types and a property that should hold UI models for each selected type from enumeration: Let's define them like:

class ViewModel
   {
     Types selectedType{get;set;}
     UiModelBase editedModel{get;set;}
   }

I want to have a content control that use datatemplateselector to change his view each time I change the selectedType.

    <ListBox x:Name="RuleTypeList" ItemsSource="{Binding Source={StaticResource Types}}" SelectedItem="{Binding Path=selectedType}"/>     
    <!--Content control-->
    <ContentControl ContentTemplateSelector="{StaticResource ruleEditTemplateSelector}" 
             Content="{Binding SelectedItem, ElementName=RuleTypeList}"/>

the PROBLEM: In DataTemplates that I create to be returned by ruleEditTemplateSelector the DataContext is Type (agree with that) but I need access to the editedModel to create my DataTemplate...I do not know how to deal with it

Thanks in advance!

Unbrace

Answer 1

The solution was not very hard....

 DataContext="{Binding RelativeSource={RelativeSource AncestorType=ContentControl},Path=DataContext}"

In this way the context of template is the same with the content of his parent and I can acces his members. I think I tryind to do that but I didn't code correct... Thanks Cstein for involving !

Unbrace

thanks! I was looking for this solution for a long time. – Edirne

Answer 2

If I understand you right you want to create your DataTemplate inside the templateselector, while the datatemplate is based on the editedModel property.

I would solve this problem this way:

Windows.xaml:

<Window.Resources>
    <local:Selector x:Key="sel"/>

    <DataTemplate x:Key="templateA">
        <TextBlock Text="{Binding editedModel.PropertyName}"/>
    </DataTemplate>

    <DataTemplate x:Key="templateB">
        <TextBlock Text="{Binding editedModel.PropertyName}"/>
    </DataTemplate>

    <DataTemplate x:Key="templateC">
        <TextBlock Text="{Binding editedModel.PropertyName}"/>
    </DataTemplate>

</Window.Resources>

Contentcontrol and listbox stay the same.

DataTemplateSelector:

public class Selector : DataTemplateSelector
{
    public override DataTemplate SelectTemplate(object item, DependencyObject container)
    {
        if (item is ClassA)
            return (container as FrameworkElement).FindResource("TemplateA") as DataTemplate;
        else if (item is ClassB)
            return (container as FrameworkElement).FindResource("TemplateB") as DataTemplate;
        else if (item is ClassC)
            return (container as FrameworkElement).FindResource("TemplateC") as DataTemplate;
        return null;
    }
}

This return an existing datatemplate depending on the item's type. I hope I understood you right and it helps you.

Blacklist

No...this is not my problem. I know the workflow. the problem is inside templateA, B,C. because editedModel.PropertyName is not found. (the data context is selectedType...) – Unbrace

If your Window.xaml's datacontext is your viewmodel and you put your datatemplates into Window.Resources tag then you can access your editedModel.PropertyName from your DataTemplate – Blacklist

Yes I have the DataTemplate in Windows.Resources and no...unfortunately it said it does not find any: editedModel.PropertyName in sectedType ....witch is true... – Unbrace

Yes it finds no property with that name as long as you don't declare it. Or did I missunderstand you? – Blacklist

I'm affraid I might not understand what you are saying... an instance of editedModel.PropertyName it already exists in code behind...why should I declare it again...I want to alter the instance that already exist. I am understanding wrong? – Unbrace