Caching templates to allow for dynamic template generation

Co-authored-by: rbeard0330 <@dul2k3BKW6m>

django_components/app_settings.py

@@ -15,6 +15,10 @@ class AppSettings:
     def LIBRARIES(self):
         return self.settings.setdefault("libraries", [])
 
+    @property
+    def TEMPLATE_CACHE_SIZE(self):
+        return self.settings.setdefault("template_cache_size", 128)
+
 
 app_settings = AppSettings()
 app_settings.__name__ = __name__

django_components/component.py

@@ -1,5 +1,6 @@
 import warnings
 from copy import copy
+from functools import lru_cache
 from itertools import chain
 
 from django.conf import settings
@@ -11,12 +12,15 @@ from django.utils.safestring import mark_safe
 # Allow "component.AlreadyRegistered" instead of having to import these everywhere
 from django_components.component_registry import AlreadyRegistered, ComponentRegistry, NotRegistered  # noqa
 
+TEMPLATE_CACHE_SIZE = getattr(settings, "COMPONENTS", {}).get('TEMPLATE_CACHE_SIZE', 128)
+
 
 class Component(metaclass=MediaDefiningClass):
 
     def __init__(self, component_name):
         self.__component_name = component_name
         self.instance_template = None
+        self.slots = {}
 
     def context(self):
         return {}
@@ -43,15 +47,16 @@ class Component(metaclass=MediaDefiningClass):
     def slots_in_template(template):
         return {node.name: node.nodelist for node in template.template.nodelist if is_slot_node(node)}
 
-    def compile_instance_template(self, slots_for_instance):
+    @lru_cache(maxsize=TEMPLATE_CACHE_SIZE)
+    def compile_instance_template(self, template_name):
         """Use component's base template and the slots used for this instance to compile
         a unified template for this instance."""
 
-        component_template = get_template(self.template({}))
+        component_template = get_template(template_name)
         slots_in_template = self.slots_in_template(component_template)
 
         defined_slot_names = set(slots_in_template.keys())
-        filled_slot_names = set(slots_for_instance.keys())
+        filled_slot_names = set(self.slots.keys())
         unexpected_slots = filled_slot_names - defined_slot_names
         if unexpected_slots:
             if settings.DEBUG:
@@ -61,21 +66,25 @@ class Component(metaclass=MediaDefiningClass):
                     )
                 )
             for unexpected_slot in unexpected_slots:
-                del slots_for_instance[unexpected_slot]
+                del self.slots[unexpected_slot]
 
-        combined_slots = dict(slots_in_template, **slots_for_instance)
+        combined_slots = dict(slots_in_template, **self.slots)
         if combined_slots:
             # Replace slot nodes with their nodelists, then combine into a single, flat nodelist
             node_iterator = ([node] if not is_slot_node(node) else combined_slots[node.name]
                              for node in component_template.template.nodelist)
 
-            self.instance_template = copy(component_template.template)
+            instance_template = copy(component_template.template)
-            self.instance_template.nodelist = NodeList(chain.from_iterable(node_iterator))
+            instance_template.nodelist = NodeList(chain.from_iterable(node_iterator))
         else:
-            self.instance_template = component_template.template
+            instance_template = component_template.template
+
+        return instance_template
 
     def render(self, context):
-        return self.instance_template.render(context)
+        template_name = self.template(context)
+        instance_template = self.compile_instance_template(template_name)
+        return instance_template.render(context)
 
     class Media:
         css = {}

django_components/templatetags/component_tags.py

@@ -100,7 +100,7 @@ class ComponentNode(Node):
         if slots:
             for slot in slots:
                 slot_dict[slot.name].extend(slot.nodelist)
-        self.component.compile_instance_template(slot_dict)
+        self.component.slots = slot_dict
 
     def __repr__(self):
         return "<Component Node: %s. Contents: %r>" % (self.component, self.component.instance_template.nodelist)

tests/django_test_setup.py

@@ -10,7 +10,10 @@ if not settings.configured:
             TEMPLATES=[{
                 'BACKEND': 'django.template.backends.django.DjangoTemplates',
                 'DIRS': ["tests/templates/"],
-            }]
+            }],
+            COMPONENTS={
+                'TEMPLATE_CACHE_SIZE': 128
+            },
         )
     else:
         settings.configure(

tests/test_component.py

@@ -2,11 +2,11 @@ from textwrap import dedent
 
 from django.template import Context
 
-from django_components import component
-
 from .django_test_setup import *  # NOQA
 from .testutils import Django111CompatibleSimpleTestCase as SimpleTestCase
 
+from django_components import component
+
 
 class ComponentRegistryTest(SimpleTestCase):
     def test_empty_component(self):
@@ -32,7 +32,6 @@ class ComponentRegistryTest(SimpleTestCase):
 
         comp = SimpleComponent("simple_component")
         context = Context(comp.context(variable="test"))
-        comp.compile_instance_template({})
 
         self.assertHTMLEqual(comp.render_dependencies(), dedent("""
             <link href="style.css" type="text/css" media="all" rel="stylesheet">
@@ -71,7 +70,6 @@ class ComponentRegistryTest(SimpleTestCase):
 
         comp = FilteredComponent("filtered_component")
         context = Context(comp.context(var1="test1", var2="test2"))
-        comp.compile_instance_template({})
 
         self.assertHTMLEqual(comp.render(context), dedent("""
             Var1: <strong>test1</strong>

tests/test_context.py

@@ -1,8 +1,9 @@
 from django.template import Context, Template
 
+from .django_test_setup import *  # NOQA
+
 from django_components import component
 
-from .django_test_setup import *  # NOQA
 from .testutils import Django111CompatibleSimpleTestCase as SimpleTestCase
 
 

tests/test_registry.py

@@ -1,5 +1,6 @@
 import unittest
 
+from .django_test_setup import *  # NOQA
 from django_components import component
 
 

tests/test_templatetags.py

@@ -2,9 +2,9 @@ from textwrap import dedent
 
 from django.template import Context, Template
 
+from .django_test_setup import *  # NOQA
 from django_components import component
 
-from .django_test_setup import *  # NOQA
 from .testutils import Django111CompatibleSimpleTestCase as SimpleTestCase
 
 

tests/testutils.py

@@ -1,3 +1,4 @@
+from django import setup
 from django.test import SimpleTestCase
 
 
@@ -5,3 +6,5 @@ class Django111CompatibleSimpleTestCase(SimpleTestCase):
     def assertHTMLEqual(self, left, right):
         left = left.replace(' type="text/javascript"', '')
         super(Django111CompatibleSimpleTestCase, self).assertHTMLEqual(left, right)
+
+setup()