How to filter a ttk.treeview in Python?

Question

I have a python tkinter application that contains a ttk.treeview widget.

The widget displays a list of files found on a specific directory tree with a specific extension - this was trivial to build with tt.treeview widget.

There is a request to enable "on-the-fly" filtering of the tree - e.g., the user types in an Entry some string, and as he/she types, the tree removes elements that don't match the typed string so far.

I was exploring the Treeview documentation, tried the detach and reattach methods but with no luck.

detach indeed removes the non-matched elements from the tree, but if the user hit Backspace, I can no longer iterate correctly on the tree to restore those detached elements as get_children method will not return them.

def filter_tree(self):
    search_by = self.search_entry.get()
    self.tree_detach_leaf_by_regex(self.current_loaded_folder, search_by, "")

def tree_detach_leaf_by_regex(self, root, regex, parent):
    if self.treeview.get_children(root):
        for child in self.treeview.get_children(root):
            self.tree_detach_leaf_by_regex(child, regex, root)
    else:
        if not re.match(regex, self.treeview.item(root)["text"]):
            self.elements_index_within_parent[root] = self.treeview.index(root)
            self.elements_parents[parent] = 1
            self.treeview.detach(root)
        else:
            self.treeview.reattach(root, parent, self.elements_index_within_parent[root])

Looking forward to read your advice.

Answer 1

To make my answer reusable by anybody, I have to tell more than directly answering your question. If you directly want to see how I do to get detached items (thus without using the method get_children which cannot get detached items' id), jump to the definition of the method whose name is _columns_searcher.

---

Introduction

Let's first define some attributes.

@property
def _to_search(self):
    key = 'to_search'
    if key not in self._cache:
        self._cache[key] = tk.StringVar()
    return self._cache[key] 

def _set_search_entry(self):  
    ent = ttk.Entry(
        self.root, # or canvas, or frame ...
        #...
        textvariable=self._to_search
    )
    ent.grid(
        #...
    )
    ent.bind(
        '<Return>',
        self._columns_searcher
    )
    return ent

@property
def search_entry(self):
    key = 'search_entry'
    if key not in self._cache:
        self._cache[key] = self._set_search_entry()
    return self._cache[key]

---

Core answer

What follows is the part which directly show how to re-attach user-detached items. First note that, as the OP mentions, get_children only return ids of attached items. Second note that the only thing you need to re-attach detached items is their id. Which implies thus to trace/save them when they are detached so as to be able to re-attach them.

_detached = set()
def _columns_searcher(self, event):
    #              originally a set            returns a tuple
    children = list(self._detached) + list(self.tree.get_children())
    self._detached = set()
    query = self._to_search.get()

    self._brut_searcher(children, query.lower())

Note that children above contains all items, be them detached.

def _brut_searcher(self, children, query):
    i_r = -1
    for item_id in children:
        text = self.tree.item(item_id)['text'] # already contains the strin-concatenation (over columns) of the row's values
        if query in text:
            i_r += 1
            self.tree.reattach(item_id, '', i_r)
        else:
            self._detached.add(item_id)
            self.tree.detach(item_id)