DataTemplate.DataType = Collection<Entity>?
Is there a way to create a data template that handles a list of items?
I have Contact.Phones (EntityCollection<Phone>
) and I want the data template to handle the list - add remove edit etc.
开发者_开发百科Is there a way to set the DataType property of the DataTemplate to generic EntityCollection<Phone>
?
In my Emerald Data Foundation (EDF) tool I solved this by creating a more powerful MarkupExtension than x:Type that could specify generic types too. That way I could write:
<DataTemplate TargetType="{edf:Type generic:ICollection{local:Entity}}" />
Here's what I used:
[MarkupExtensionReturnType(typeof(Type))]
public class TypeExtension : MarkupExtension
{
public TypeExtension() { }
public TypeExtension(string typeName) { TypeName = typeName; }
public TypeExtension(Type type) { Type = type; }
public string TypeName { get; set; }
public Type Type { get; set; }
public override object ProvideValue(IServiceProvider serviceProvider)
{
if(Type==null)
{
IXamlTypeResolver typeResolver = serviceProvider.GetService(typeof(IXamlTypeResolver)) as IXamlTypeResolver;
if(typeResolver==null) throw new InvalidOperationException("EDF Type markup extension used without XAML context");
if(TypeName==null) throw new InvalidOperationException("EDF Type markup extension used without Type or TypeName");
Type = ResolveGenericTypeName(TypeName, (name) =>
{
Type result = typeResolver.Resolve(name);
if(result==null) throw new Exception("EDF Type markup extension could not resolve type " + name);
return result;
});
}
return Type;
}
public static Type ResolveGenericTypeName(string name, Func<string, Type> resolveSimpleName)
{
if(name.Contains('{'))
name = name.Replace('{', '<').Replace('}', '>'); // Note: For convenience working with XAML, we allow {} instead of <> for generic type parameters
if(name.Contains('<'))
{
var match = _genericTypeRegex.Match(name);
if(match.Success)
{
Type[] typeArgs = (
from arg in match.Groups["typeArgs"].Value.SplitOutsideParenthesis(',')
select ResolveGenericTypeName(arg, resolveSimpleName)
).ToArray();
string genericTypeName = match.Groups["genericTypeName"].Value + "`" + typeArgs.Length;
Type genericType = resolveSimpleName(genericTypeName);
if(genericType!=null && !typeArgs.Contains(null))
return genericType.MakeGenericType(typeArgs);
}
}
return resolveSimpleName(name);
}
static Regex _genericTypeRegex = new Regex(@"^(?<genericTypeName>\w+)<(?<typeArgs>\w+(,\w+)*)>$");
}
The generic type name parsing code is in a separate method because it is also used by some other code in EDF. You could combine it all into one method.
Wrap your generic list in a new class, which subclasses your generic list without adding anything. This makes it possible to bind to the list from XAML. This is described here: Can I specify a generic type in XAML (pre .NET 4 Framework)?
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