How can a custom type loaded through XAML obtain a reference to the root object

Question

I am attempting to use XAML to represent and load a graph of custom types that form a semantic model for a business domain.

One thing I would like to do is to be able to obtain a reference to the "root object" of the graph from an object deeper in the tree. I cannot find any straightforward way of doing this other than resorting to barbarous practices like having the root object as a singleton.

Any ideas?

Answer 1

I don't know that this is a problem unique to XAML. All XAML is doing is instantiating your "child" objects and adding them to a collection property on the "parent" object. So if you had something like:

<my:Category Name="Products">
    <my:Category.Subcategories>
        <my:Category Name="Clothing" />
        <my:Category Name="Jewellery" />
    </my:Category.Subcategories>
</my:Category>

... then you'd end up with a "Products" category with two subcategories. It'd be up to you to code up your "Category" class in such a way that adding a subcategory saves a reference to the "owner" of that subcategory somewhere. I'd probably use a custom collection type (override the Add and Remove methods so that they set the "Parent" or "Owner" property on the object being added).