add

Author: baseplate-admin

django_ltree/managers.py

@@ -27,7 +27,6 @@ def create_child(self, parent=None, **kwargs):
         path_generator = PathGenerator(
             prefix,
             skip=paths_in_use.values_list("path", flat=True),
-            label_size=getattr(self.model, "label_size"),
         )
         kwargs["path"] = path_generator.next()
         return self.create(**kwargs)

django_ltree/paths.py

@@ -2,17 +2,22 @@
 from itertools import product
 
 from django_ltree.fields import PathValue
+import math
 
 
 class PathGenerator(object):
-    _default_label_size = 6  # Postgres limits this to 256
+    # _default_label_size = 6  # Postgres limits this to 256
+
+    def __init__(self, prefix=None, skip=None):
+        combinations = string.digits + string.ascii_letters
 
-    def __init__(self, prefix=None, skip=None, label_size=None):
         self.skip_paths = [] if skip is None else skip[:]
         self.path_prefix = prefix if prefix else []
         self.product_iterator = product(
-            string.digits + string.ascii_letters,
-            repeat=label_size or self._default_label_size,
+            combinations,
+            repeat=self.guess_the_label_size(
+                path_size=len(self.skip_paths), combination_size=len(combinations)
+            ),
         )
 
     def __iter__(self):
@@ -26,3 +31,25 @@ def __next__(self):
                 return path
 
     next = __next__
+
+    @staticmethod
+    def guess_the_label_size(path_size: int, combination_size: int):
+        # The theoritical limit for this at the time of writing is 2538557185841324496 (python 3.12.2)
+        calculated_path_size = 0
+        # The theoritical limit for this at the time of writing is 32 (python 3.12.2)
+        label_size = 0
+
+        # THIS IS AN VERY IMPORTANT CHECK
+        last = 0
+
+        while calculated_path_size < path_size:
+            possible_cominations = math.comb(combination_size, label_size)
+
+            if last > possible_cominations:
+                raise ValueError("We approached the limit of `math.comb`")
+
+            last = possible_cominations
+            calculated_path_size += possible_cominations
+            label_size += 1
+
+        return label_size

poetry.lock

@@ -4,15 +4,19 @@
 
 
 def test_create():
-    assert str(PathValue([1, 2, 3, 4, 5])) == '1.2.3.4.5'
-    assert str(PathValue((1, 3, 5, 7))) == '1.3.5.7'
-    assert str(PathValue('hello.world')) == 'hello.world'
+    assert str(PathValue([1, 2, 3, 4, 5])) == "1.2.3.4.5"
+    assert str(PathValue((1, 3, 5, 7))) == "1.3.5.7"
+    assert str(PathValue("hello.world")) == "hello.world"
     assert str(PathValue(5)) == "5"
 
     def generator():
-        yield '100'
-        yield 'bottles'
-        yield 'of'
-        yield 'beer'
+        yield "100"
+        yield "bottles"
+        yield "of"
+        yield "beer"
 
-    assert str(PathValue(generator())) == '100.bottles.of.beer'
+    assert str(PathValue(generator())) == "100.bottles.of.beer"
+
+
+def test_automatic_generation_of_label():
+    pass