Deferred static files (#77)

- Deferred static file components
- Docs for deferred static files
- Bump minimum IDOM version
- Create PR templates
- Sync issue form template with `idom-team/idom`
- Pin selenium to 4.2 for compatibility
- Bump django-idom to v1.1.0
- Docstring for component template tag
- Minor readme wordsmithing

Author: Archmonger

Diff for: .github/ISSUE_TEMPLATE/issue-form.yml

@@ -14,10 +14,3 @@ body:
     description: Describe what ought to be done, and why that will address the reasons for action mentioned above.
   validations:
     required: false
-- type: textarea
-  attributes:
-    label: Work Items
-    description: |
-      An itemized list or detailed description of the work to be done to based on the proposed actions above.
-  validations:
-    required: false

Diff for: .github/pull_request_template.md

@@ -0,0 +1,11 @@
+# Description
+
+A summary of the changes.
+
+# Checklist:
+
+Please update this checklist as you complete each item:
+
+-   [ ] Tests have been included for all bug fixes or added functionality.
+-   [ ] The `changelog.rst` has been updated with any significant changes, if necessary.
+-   [ ] GitHub Issues which may be closed by this PR have been linked.

Diff for: CHANGELOG.md

@@ -24,6 +24,16 @@ Types of changes are to be listed in this order
 
 -   Nothing (yet)
 
+## [1.1.0] - 2022-06-25
+
+### Added
+
+-   `django_css` and `django_js` components to defer loading CSS & JS files until needed.
+
+### Changed
+
+-   Bumped the minimum IDOM version to 0.39.0
+
 ## [1.0.0] - 2022-05-22
 
 ### Added
@@ -103,6 +113,7 @@ Types of changes are to be listed in this order
 -   Support for IDOM within the Django
 
 [unreleased]: https://github.com/idom-team/django-idom/compare/1.0.0...HEAD
+[1.1.0]: https://github.com/idom-team/django-idom/compare/1.0.0...1.1.0
 [1.0.0]: https://github.com/idom-team/django-idom/compare/0.0.5...1.0.0
 [0.0.5]: https://github.com/idom-team/django-idom/compare/0.0.4...0.0.5
 [0.0.4]: https://github.com/idom-team/django-idom/compare/0.0.3...0.0.4

Diff for: README.md

@@ -19,8 +19,6 @@ Any Python web framework with Websockets can support IDOM. See below for what fr
 
 <!--intro-end-->
 
----
-
 # At a Glance
 
 ## `my_app/components.py`
@@ -46,7 +44,7 @@ def HelloWorld(recipient: str):
 
 <!--html-header-start-->
 
-In your **Django app**'s HTML located within your `templates` folder, you can now embed your IDOM component using the `component` template tag. Within this tag, you will need to type in your dotted path to the component function as the first argument.
+In your **Django app**'s HTML template, you can now embed your IDOM component using the `component` template tag. Within this tag, you will need to type in your dotted path to the component function as the first argument.
 
 Additonally, you can pass in keyword arguments into your component function. For example, after reading the code below, pay attention to how the function definition for `HelloWorld` (_in the previous example_) accepts a `recipient` argument.
 
@@ -65,8 +63,6 @@ Additonally, you can pass in keyword arguments into your component function. For
 
 <!--html-code-end-->
 
----
-
 # Resources
 
 <!--resources-start-->

Diff for: docs/features/components.md

@@ -0,0 +1,121 @@
+## Django CSS
+
+Allows you to defer loading a CSS stylesheet until a component begins rendering. This stylesheet must be stored within [Django's static files](https://docs.djangoproject.com/en/dev/howto/static-files/).
+
+```python title="components.py"
+from idom import component, html
+from django_idom.components import django_css
+
+@component
+def MyComponent():
+    return html.div(
+        django_css("css/buttons.css"),
+        html.button("My Button!"),
+    )
+```
+
+??? question "Should I put `django_css` at the top of my component?"
+
+    Yes, if the stylesheet contains styling for your component.
+
+??? question "Can I load static CSS using `html.link` instead?"
+
+    While you can load stylesheets with `html.link`, keep in mind that loading this way **does not** ensure load order. Thus, your stylesheet will be loaded after your component is displayed. This would likely cause some visual jankiness, so use this at your own discretion.
+
+    Here's an example on what you should avoid doing for Django static files:
+
+    ```python
+    from idom import component, html
+    from django.templatetags.static import static
+
+    @component
+    def MyComponent():
+        return html.div(
+            html.link({"rel": "stylesheet", "href": static("css/buttons.css")}),
+            html.button("My Button!"),
+        )
+    ```
+
+??? question "How do I load external CSS?"
+
+    `django_css` can only be used with local static files.
+
+    For external CSS, substitute `django_css` with `html.link`.
+
+    ```python
+    from idom import component, html
+
+    @component
+    def MyComponent():
+        return html.div(
+            html.link({"rel": "stylesheet", "href": "https://example.com/external-styles.css"}),
+            html.button("My Button!"),
+        )
+    ```
+
+??? question "Why not load my CSS in `#!html <head>`?"
+
+    Traditionally, stylesheets are loaded in your `#!html <head>` using the `#!jinja {% load static %}` template tag.
+
+    To help improve webpage load times, you can use the `django_css` component to defer loading your stylesheet until it is needed.
+
+## Django JS
+
+Allows you to defer loading JavaScript until a component begins rendering. This JavaScript must be stored within [Django's static files](https://docs.djangoproject.com/en/dev/howto/static-files/).
+
+```python title="components.py"
+from idom import component, html
+from django_idom.components import django_js
+
+@component
+def MyComponent():
+    return html.div(
+        html.button("My Button!"),
+        django_js("js/scripts.js"),
+    )
+```
+
+??? question "Should I put `django_js` at the bottom of my component?"
+
+    Yes, if your scripts are reliant on the contents of the component.
+
+??? question "Can I load static JavaScript using `html.script` instead?"
+
+    While you can load JavaScript with `html.script`, keep in mind that loading this way **does not** ensure load order. Thus, your JavaScript will likely be loaded at an arbitrary time after your component is displayed.
+
+    Here's an example on what you should avoid doing for Django static files:
+
+    ```python
+    from idom import component, html
+    from django.templatetags.static import static
+
+    @component
+    def MyComponent():
+        return html.div(
+            html.script({"src": static("js/scripts.js")}),
+            html.button("My Button!"),
+        )
+    ```
+
+??? question "How do I load external JS?"
+
+    `django_js` can only be used with local static files.
+
+    For external JavaScript, substitute `django_js` with `html.script`.
+
+    ```python
+    from idom import component, html
+
+    @component
+    def MyComponent():
+        return html.div(
+            html.script({"src": static("https://example.com/external-scripts.js")}),
+            html.button("My Button!"),
+        )
+    ```
+
+??? question "Why not load my JS in `#!html <head>`?"
+
+    Traditionally, JavaScript is loaded in your `#!html <head>` using the `#!jinja {% load static %}` template tag.
+
+    To help improve webpage load times, you can use the `django_js` component to defer loading your JavaScript until it is needed.

Diff for: docs/features/hooks.md

@@ -18,7 +18,7 @@ def MyComponent():
     return html.div(my_websocket)
 ```
 
----
+
 
 ## Use Scope
 
@@ -34,7 +34,6 @@ def MyComponent():
     return html.div(my_scope)
 ```
 
----
 
 ## Use Location
 

Diff for: docs/stylesheets/extra.css

@@ -6,3 +6,7 @@
 .md-header {
 	background-color: var(--md-footer-bg-color--dark);
 }
+
+.md-typeset :is(.admonition, details) {
+	margin: 1em 0;
+}

Diff for: mkdocs.yml

@@ -9,6 +9,7 @@ nav:
           - 4. Render Your View: getting-started/render-view.md
           - 5. Learn More: getting-started/learn-more.md
     - Exclusive Features:
+          - Components: features/components.md
           - Hooks: features/hooks.md
           - Template Tag: features/templatetag.md
     - Contribute:

Diff for: requirements/pkg-deps.txt

@@ -1,3 +1,3 @@
 channels >=3.0.0
-idom >=0.38.0, <0.39.0
+idom >=0.39.0, <0.40.0
 aiofile >=3.0

Diff for: requirements/test-env.txt

@@ -1,3 +1,3 @@
 django
-selenium
+selenium <= 4.2.0
 twisted

Diff for: src/django_idom/__init__.py

@@ -1,7 +1,7 @@
-from . import hooks
+from . import components, hooks
 from .websocket.consumer import IdomWebsocket
 from .websocket.paths import IDOM_WEBSOCKET_PATH
 
 
-__version__ = "1.0.0"
-__all__ = ["IDOM_WEBSOCKET_PATH", "IdomWebsocket", "hooks"]
+__version__ = "1.1.0"
+__all__ = ["IDOM_WEBSOCKET_PATH", "IdomWebsocket", "hooks", "components"]

Diff for: src/django_idom/components.py

@@ -0,0 +1,61 @@
+import os
+
+from django.contrib.staticfiles.finders import find
+from idom import component, html
+
+from django_idom.config import IDOM_CACHE
+
+
+@component
+def django_css(static_path: str):
+    """Fetches a CSS static file for use within IDOM. This allows for deferred CSS loading.
+
+    Args:
+        static_path: The path to the static file. This path is identical to what you would
+        use on a `static` template tag.
+    """
+    return html._(
+        html.script(
+            """
+            let parentTag = document.currentScript;
+            console.log(parentTag);
+            //parentTag.attachShadow({ mode: 'open' });
+            """
+        ),
+        html.style(_cached_static_contents(static_path)),
+    )
+
+
+@component
+def django_js(static_path: str):
+    """Fetches a JS static file for use within IDOM. This allows for deferred JS loading.
+
+    Args:
+        static_path: The path to the static file. This path is identical to what you would
+        use on a `static` template tag.
+    """
+    return html.script(_cached_static_contents(static_path))
+
+
+def _cached_static_contents(static_path: str):
+    # Try to find the file within Django's static files
+    abs_path = find(static_path)
+    if not abs_path:
+        raise FileNotFoundError(
+            f"Could not find static file {static_path} within Django's static files."
+        )
+
+    # Fetch the file from cache, if available
+    # Cache is preferrable to `use_memo` due to multiprocessing capabilities
+    last_modified_time = os.stat(abs_path).st_mtime
+    cache_key = f"django_idom:static_contents:{static_path}"
+    file_contents = IDOM_CACHE.get(cache_key, version=last_modified_time)
+    if file_contents is None:
+        with open(abs_path, encoding="utf-8") as static_file:
+            file_contents = static_file.read()
+        IDOM_CACHE.delete(cache_key)
+        IDOM_CACHE.set(
+            cache_key, file_contents, timeout=None, version=last_modified_time
+        )
+
+    return file_contents

Diff for: src/django_idom/templatetags/idom.py

@@ -15,6 +15,21 @@
 
 @register.inclusion_tag("idom/component.html")
 def component(_component_id_, **kwargs):
+    """
+    This tag is used to embed an existing IDOM component into your HTML template.
+
+    The first argument within this tag is your dotted path to the component function.
+
+    Subsequent values are keyworded arguments are passed into your component::
+
+        {% load idom %}
+        <!DOCTYPE html>
+        <html>
+        <body>
+            {% component "example_project.my_app.components.HelloWorld" recipient="World" %}
+        </body>
+        </html>
+    """
     _register_component(_component_id_)
 
     class_ = kwargs.pop("class", "")

Diff for: tests/test_app/components.py

@@ -71,3 +71,27 @@ def UseLocation():
         f"UseLocation: {location}",
         idom.html.hr(),
     )
+
+
+@idom.component
+def StaticCSS():
+    return idom.html.div(
+        {"id": "static-css"},
+        django_idom.components.django_css("static-css-test.css"),
+        idom.html.div({"style": {"display": "inline"}}, "StaticCSS: "),
+        idom.html.button("This text should be blue."),
+        idom.html.hr(),
+    )
+
+
+@idom.component
+def StaticJS():
+    success = False
+    return idom.html._(
+        idom.html.div(
+            {"id": "static-js", "data-success": success},
+            f"StaticJS: {success}",
+            django_idom.components.django_js("static-js-test.js"),
+        ),
+        idom.html.hr(),
+    )

Diff for: tests/test_app/static/static-css-test.css

@@ -0,0 +1,3 @@
+#static-css button {
+    color: rgba(0, 0, 255, 1);
+}

Diff for: tests/test_app/static/static-js-test.js

@@ -0,0 +1,3 @@
+let el = document.body.querySelector("#static-js");
+el.textContent = "StaticJS: True";
+el.dataset.success = "true";

Diff for: tests/test_app/templates/base.html

@@ -19,6 +19,8 @@ <h1>IDOM Test Page</h1>
   <div>{% component "test_app.components.UseWebsocket" %}</div>
   <div>{% component "test_app.components.UseScope" %}</div>
   <div>{% component "test_app.components.UseLocation" %}</div>
+  <div>{% component "test_app.components.StaticCSS" %}</div>
+  <div>{% component "test_app.components.StaticJS" %}</div>
 </body>
 
 </html>

Diff for: tests/test_app/tests/test_components.py

@@ -59,6 +59,16 @@ def test_use_location(self):
             element = self.driver.find_element_by_id("use-location")
             self.assertEqual(element.get_attribute("data-success"), "true")
 
+        def test_static_css(self):
+            element = self.driver.find_element_by_css_selector("#static-css button")
+            self.assertEqual(
+                element.value_of_css_property("color"), "rgba(0, 0, 255, 1)"
+            )
+
+        def test_static_js(self):
+            element = self.driver.find_element_by_id("static-js")
+            self.assertEqual(element.get_attribute("data-success"), "true")
+
 
 def make_driver(page_load_timeout, implicit_wait_timeout):
     options = webdriver.ChromeOptions()