TACC
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diff --git a/‎taccsite_cms/contrib/_docs/taccsite_static_article.md‎
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diff --git a/‎taccsite_cms/contrib/helpers.py‎
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diff --git a/‎taccsite_cms/contrib/taccsite_static_article_list/README.md‎
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diff --git a/‎taccsite_cms/contrib/taccsite_static_article_list/__init__.py‎ b/‎taccsite_cms/contrib/taccsite_static_article_list/__init__.py‎
@@ -0,0 +1,11 @@
+# How to Conditionally Render Child Plugins
+
+```handlebars
+    {% for plugin_instance in instance.child_plugin_instances %}
+      {% if plugin_instance.plugin_type == 'LinkPlugin' %}
+        <a href="{{ link }}" <!-- ... -->>
+          <!-- ... -->
+        </a>
+      {% endif %}
+    {% endfor %}
+```
@@ -0,0 +1,62 @@
+# How to Handle "Non-Nullable" "Default Value"
+
+## Sample Error
+
+```text
+You are trying to add a non-nullable field '...'
+to choice without a default; we can't do that
+(the database needs something to populate existing rows).
+Please select a fix:
+ 1) Provide a one-off default now (will be set on all existing rows)
+ 2) Quit, and let me add a default in models.py
+Select an option:
+```
+
+## Explanations
+
+- (blog post) [What do you do when 'makemigrations' is telling you About your Lack of Default Value](https://chrisbartos.com/articles/what-do-you-do-when-makemigrations-is-telling-you-about-your-lack-of-default-value/)
+- (video) [You are trying to add a non-nullable field ' ' to ' ' without a default; we can't do that](https://www.youtube.com/watch?v=NgaTUEijQSQ)
+
+## Solutions
+
+### For `cmsplugin_ptr`
+
+1. ☑ Select option 1), then see:
+    - [Follow-Up Error](#follow-up-error)
+    - [Notes ▸ `cmsplugin_ptr`](#cmsplugin_ptr)
+
+### For Other Fields
+
+1. ⚠ Select option 1) and hope for the best.
+2. ☑ Select option 2) and provide a sensible default (_not_ `None` a.k.a. null).
+3. ⚠ (blog post) (hack) [Add A Migration For A Non-Null Foreignkey Field In Django](https://jaketrent.com/post/add-migration-nonnull-foreignkey-field-django)
+
+## Follow-Up Error
+
+If you allowed Null to be set as default, then you may have this new error:
+
+```text
+django.db.utils.IntegrityError: column "..." contains null values
+```
+
+Solutions:
+
+1. [delete _relevant_ migration files and rebuild migrations](https://stackoverflow.com/a/37244199/11817077)
+2. [delete _all_ migration files and rebuild migrations](https://stackoverflow.com/a/37242930/11817077)
+
+## Notes
+
+### `cmsplugin_ptr`
+
+  If the field is `cmsplugin_ptr` then know that
+
+  - [it is a database relationship field managed automatically by Django](https://github.com/nephila/djangocms-blog/issues/316#issuecomment-242292787),
+  - you may see it in workarounds for other plugins ([source a](https://github.com/django-cms/djangocms-link/blob/3.0.0/djangocms_link/models.py#L125), [source b](https://github.com/django-cms/djangocms-picture/blob/3.0.0/djangocms_picture/models.py#L208)),
+  - you should __not__ add or overwrite it unless you know what you are doing.
+
+  _W. Bomar learned everything in the intitial version of this document after trying to overwrite `cmsplugin_ptr` while extending its model from [source a](https://github.com/django-cms/djangocms-link/blob/3.0.0/djangocms_link/models.py#L125). His solution was [delete _all_ migration files and rebuild migrations](https://stackoverflow.com/a/37242930/11817077)._
+
+## Appendix
+
+- [Django CMS ▸ How to create Plugins ▸ Handling Relations](https://docs.django-cms.org/en/release-3.7.x/how_to/custom_plugins.html#handling-relations)
+- [[BUG] Plugins with models that don't directly inherit from CMSPlugin or an abstract model cannot be copied](https://github.com/django-cms/django-cms/issues/6987)
@@ -0,0 +1,66 @@
+# Static Article Plugins
+
+## Intention
+
+Support static addition of news articles that originate from a Core news site.
+
+A [dynamic solution that pulls form the Core news site](https://github.com/TACC/Core-CMS/issues/69) is preferable.
+
+But this is not available due to constrainst of architecture, time, or ability.
+
+## Architecture
+
+### (Currently) Add Image via Child Plugin Instead of Via Fields
+
+Instead, the image fields should be in the plugin, __not__ via a child plugin, but a solution has not yet been implemented.
+
+#### Hope for the Future
+
+The `AbstractLink` model was successfully extended.
+
+See:
+    - [./how-to-extend-django-cms-plugin.md](./how-to-extend-django-cms-plugin.md)
+    - [../taccsite_static_article_preview](../taccsite_static_article_preview)
+    - [../taccsite_static_article_list](../taccsite_static_article_list)
+
+#### Failed Attempt
+
+1. Build model so it extends `AbstractPicture` from `djangocms-picture`.
+2. Tweak model to sweep bugs under the rug.
+3. Quit when he was unable to resolve the error,
+    `TaccsiteStaticNewsArticlePreview has no field named 'cmsplugin_ptr_id'`
+    upon saving a plugin instance.
+4. Learn:
+    - [one should not try to reduce `AbstractPicture`](https://stackoverflow.com/a/3674714/11817077)
+    - [one should not subclass a subclass of `CMSPlugin`](https://github.com/django-cms/django-cms/blob/3.7.4/cms/models/pluginmodel.py#L104)
+
+#### Abandoned Code
+
+```python
+from djangocms_picture.models import AbstractPicture
+
+# To allow user to not set image
+# FAQ: Emptying the clean() method avoids picture validation
+# SEE: https://github.com/django-cms/djangocms-picture/blob/3.0.0/djangocms_picture/models.py#L278
+def skip_image_validation():
+    pass
+
+class TaccsiteStaticNewsArticlePreview(AbstractPicture):
+    #
+    # …
+    #
+
+    # Remove error-prone attribute from parent class
+    # FAQ: Avoid error when running `makemigrations`:
+    #      "You are trying to add a non-nullable field 'cmsplugin_ptr' […]"
+    # SEE: https://github.com/django-cms/djangocms-picture/blob/3.0.0/djangocms_picture/models.py#L212
+    # SEE: https://github.com/django-cms/djangocms-picture/blob/3.0.0/djangocms_picture/models.py#L234
+    cmsplugin_ptr = None
+
+    class Meta:
+        abstract = False
+
+    # Validate
+    def clean(self):
+        skip_image_validation()
+```
@@ -15,7 +15,23 @@ def get_choices(choice_dict):
 
 
 
-# GH-93, GH-142, GH-133: Upcoming functions here (ease merge conflict, maybe)
+# Filter Django `models.CharField` `choices`
+# SEE: get_choices
+def filter_choices_by_prefix(choices, prefix):
+    """Reduce sequence of choices to items whose values begin with given string
+    :param List[Tuple[str, str], ...] choices: the sequence to filter
+    :param str prefix: the starting text required of an item value to retain it
+    :returns: a sequence for django.db.models.CharField.choices
+    :rtype: List[Tuple[str, str], ...]
+    """
+    new_choices = []
+
+    for choice in choices:
+        should_keep = choice[0].startswith(prefix)
+        if should_keep:
+            new_choices.append(choice)
+
+    return new_choices
 
 
 
@@ -28,7 +44,26 @@ def concat_classnames(classes):
 
 
 
-# GH-93, GH-142, GH-133: Upcoming functions here (ease merge conflict, maybe)
+# Create a list clone that has another list shoved into it
+# SEE: https://newbedev.com/how-to-insert-multiple-elements-into-a-list
+def insert_at_position(position, list, list_to_insert):
+    """Insert list at position within another list
+    :returns: New list
+    """
+    return list[:position] + list_to_insert + list[position:]
+
+
+
+# Get the date from a list that is nearest
+# SEE: https://stackoverflow.com/a/32237949/11817077
+def get_nearest(items, pivot):
+    """Get nearest date (or other arithmatic value)
+    :returns: The item value nearest the given "pivot" value
+    """
+    return min(items, key=lambda x: abs(x - pivot))
+
+
+
 # Get list of indicies of items that start with text
 # SEE: https://stackoverflow.com/a/67393343/11817077
 def get_indices_that_start_with(text, list):
@@ -39,6 +74,129 @@ def get_indices_that_start_with(text, list):
     return [i for i in range(len(list)) if list[i].startswith(text)]
 
 
+
+# Populate class attribute of plugin instances
+def add_classname_to_instances(classname, plugin_instances):
+    """Add class names to class attribute of plugin instances"""
+    for instance in plugin_instances:
+        # A plugin must not have any class set
+        if not hasattr(instance.attributes, 'class'):
+            instance.attributes['class'] = ''
+
+        # The class should occur before any CMS or user classes
+        # FAQ: This keeps plugin author classes together
+        instance.attributes['class'] = instance.attributes['class'] + classname
+
+
+
+# Get date nearest today
+
+from datetime import date
+
+# HELP: Can this logic be less verbose?
+# HELP: Is the `preferred_time_period` parameter effectual?
+def which_date_is_nearest_today(date_a, date_b, preferred_time_period):
+    """
+    Returns whether each date is today or nearest today, and whether nearest date is past or today or future.
+    Only two dates are supported. You may prefer 'future' or 'past' date(s).
+    If both dates are the same date, then both are reported as True.
+    :param datetime date_a: a date "A" to compare
+    :param datetime date_b: a date "B" to compare
+    :param str preferred_time_period: whether to prefer 'future' or 'past' dates
+    :returns:
+        A tuple of tuples:
+        ((
+            ``boolean`` of whether ``date_a`` is nearest,
+            ``string`` of ``date_a`` time period ``past``/``today``/``future``
+        ),
+        (
+            ``boolean`` of whether ``date_b`` is nearest,
+            ``string`` of ``date_b`` time period ``past``/``today``/``future``
+        )),
+    :rtype: tuple
+    """
+    today = date.today()
+    is_a = False
+    is_b = False
+    a_time_period = 'today'
+    b_time_period = 'today'
+
+    # Match preferred time
+
+    if today in {date_a, date_b}:
+        is_a = True
+        is_b = True
+        a_time_period = 'today'
+        b_time_period = 'today'
+
+    elif preferred_time_period == 'future':
+        is_a = date_a and date_a >= today
+        is_b = date_b and date_b >= today
+        if is_a: a_time_period = 'future'
+        if is_b: b_time_period = 'future'
+        if not is_a and not is_b:
+            is_a = date_a and date_a < today
+            is_b = date_b and date_b < today
+            if is_a: a_time_period = 'past'
+            if is_b: b_time_period = 'past'
+
+    elif preferred_time_period == 'past':
+        is_a = date_a and date_a < today
+        is_b = date_b and date_b < today
+        if is_a: a_time_period = 'past'
+        if is_b: b_time_period = 'past'
+        if not is_a and not is_b:
+            is_a = date_a and date_a >= today
+            is_b = date_b and date_b >= today
+            if is_a: a_time_period = 'future'
+            if is_b: b_time_period = 'future'
+
+    # Show nearest date
+    if is_a and is_b and date_a != date_b:
+        nearest_date = get_nearest((date_a, date_b), today)
+
+        if date_a == nearest_date:
+            is_b = False
+        if date_b == nearest_date:
+            is_a = False
+
+    return ((is_a, a_time_period), (is_b, b_time_period))
+
+
+
+# Allow plugins to set max number of nested children
+
+from django.shortcuts import render
+
+# SEE: https://github.com/django-cms/django-cms/issues/5102#issuecomment-597150141
+class AbstractMaxChildrenPlugin():
+    """
+    Abstract extension of `CMSPluginBase` that allows setting maximum amount of nested/child plugins.
+    Usage:
+    1. Extend this class,
+       after extending `CMSPluginBase` or a class that extends `CMSPluginBase`.
+    2. Set `max_children` to desired limit.
+    """
+
+    max_children = None
+
+    def add_view(self,request, form_url='', extra_context=None):
+
+        if self.max_children:
+            # FAQ: Placeholders do not have a parent, only plugins do
+            if self._cms_initial_attributes['parent']:
+                num_allowed = len([v for v in self._cms_initial_attributes['parent'].get_children() if v.get_plugin_instance()[0] is not None])
+            else:
+                num_allowed = len([v for v in self.placeholder.get_plugins() if v.get_plugin_instance()[0] is not None and v.get_plugin_name() == self.name])
+
+            if num_allowed >= self.max_children:
+                return render(request , "path/to/your/max_reached_template.html", {
+                    'max_children': self.max_children,
+                })
+        return super(AbstractMaxChildrenPlugin, self).add_view(request, form_url, extra_context)
+
+
+
 # Tweak validation on Django CMS `AbstractLink` for TACC
 
 from cms.models.pluginmodel import CMSPlugin
@@ -82,8 +240,9 @@ def clean(self):
         if len(err.messages):
             raise err
 
-# Get name of field from a given model
 
+
+# Get name of field from a given model
 # SEE: https://stackoverflow.com/a/14498938/11817077
 def get_model_field_name(model, field_name):
     model_field_name = model._meta.get_field(field_name).verbose_name.title()
 
@@ -0,0 +1,3 @@
+# Static Article List
+
+See [./_docs/taccsite_static_article.md](./_docs/taccsite_static_article.md).
Original file line number	Diff line number	Diff line change
`@@ -0,0 +1,3 @@`
	`1`	`+# Static Article List`
	`2`	`+`
	`3`	`+See [./_docs/taccsite_static_article.md](./_docs/taccsite_static_article.md).`