Question

I need to filter a hierarchical list like:

• Folder 1
• Folder 2
  • Document 1
  • Document 2
  • Folder 4
    • Document 3
    • Document 4
• Folder 3
  • Document

Each folder has folders and/or documents. Each document has a Status enum.
How can i get all empty Folders or with documents where the status from the document is on “Deleted”?

var folders = from f in context.Folders
              // where f.Documents.All( d => d.Status == DocumentStatus.Deleted )
              select f;

Lazy loading is enabled.

Answer 1

How about this:

Folders.Where(folder => folder.Documents.Any(document => document.Status == DocumentStatus.Deleted));

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Unfortunately you have a more complex structure, the above linq statement will work only of folders have documents and not other folders.

To do what you want to do you will have to define a Predicate manually and filter with that, because in the case that a folder has children which are folders themselves, you have to recursively call the filter method to see if the condition is true.