add a couple of filefield django code examples

mattmakai · mattmakai · commit 7a06f568efcc · 2019-10-13T09:14:19.000-04:00
diff --git a/content/pages/examples/django/django-db-models-filefield.markdown b/content/pages/examples/django/django-db-models-filefield.markdown
@@ -0,0 +1,158 @@
+title: django.db.models FileField Example Code
+category: page
+slug: django-db-models-filefield-examples
+sortorder: 50127
+toc: False
+sidebartitle: django.db.models FileField
+meta: Python code examples for the FileField class used in the Django ORM, found within the django.db.models module of the Django project. 
+
+
+[FileField](https://github.com/django/django/blob/master/django/db/models/fields/__init__.py)
+is a [Django ORM](/django-orm.html) field-to-column mapping for
+uploading files from the client to the [Django](/django.html)
+application.
+
+`FileField` is defined within the 
+[django.db.models.fields](https://github.com/django/django/blob/master/django/db/models/fields/__init__.py)
+module but is typically referenced from
+[django.db.models](https://github.com/django/django/tree/master/django/db/models)
+rather than including the `fields` module reference.
+
+
+## Example 1 from dccnsys
+[dccnsys](https://github.com/dccnconf/dccnsys) is a conference registration
+system built with [Django](/django.html). The code is open source under the
+[MIT license](https://github.com/dccnconf/dccnsys/blob/master/LICENSE).
+
+[**dccnsys / wwwdccn / submissions / models.py**](https://github.com/dccnconf/dccnsys/blob/master/wwwdccn/submissions/models.py)
+
+```python
+import os
+
+from django.conf import settings
+from django.utils.translation import ugettext_lazy as _
+from django.contrib.auth import get_user_model
+~~from django.db import models
+
+from conferences.models import Topic, SubmissionType, Conference
+
+User = get_user_model()
+
+
+TITLE_MAX_LENGTH = 250
+ABSTRACT_MAX_LENGTH = 2500  # 250 words
+
+
+def get_review_manuscript_full_path(instance, filename):
+    ext = filename.split('.')[-1]
+    root = settings.MEDIA_PRIVATE_ROOT
+    cpk = instance.conference.pk if instance.conference else 'unknown_conf'
+    path = f'{root}/{cpk}/submissions'
+    name = f'SID{instance.pk:05d}'
+    return f'{path}/{name}.{ext}'
+
+
+class Submission(models.Model):
+    SUBMITTED = 'SUBMIT'
+    UNDER_REVIEW = 'REVIEW'
+    REJECTED = 'REJECT'
+    ACCEPTED = 'ACCEPT'
+    IN_PRINT = 'PRINT'
+    PUBLISHED = 'PUBLISH'
+
+    STATUS_CHOICE = (
+        (SUBMITTED, _('Submitted')),
+        (UNDER_REVIEW, _('Review')),
+        (REJECTED, _('Rejected')),
+        (ACCEPTED, _('Accepted')),
+        (IN_PRINT, _('In-print')),
+        (PUBLISHED, _('Published')),
+    )
+
+    conference = models.ForeignKey(
+        Conference,
+        on_delete=models.SET_NULL,
+        null=True,
+    )
+
+    title = models.CharField(
+        max_length=TITLE_MAX_LENGTH,
+        default="",
+        verbose_name=_('Title'),
+    )
+
+    abstract = models.CharField(
+        max_length=ABSTRACT_MAX_LENGTH,
+        default="",
+        verbose_name=_('Abstract'),
+    )
+
+    topics = models.ManyToManyField(
+        Topic,
+        verbose_name=_('Topics'),
+    )
+
+    stype = models.ForeignKey(
+        SubmissionType,
+        related_name='submissions',
+        verbose_name=_('Submission type'),
+        on_delete=models.SET_NULL,
+        null=True,
+    )
+
+    status = models.CharField(
+        choices=STATUS_CHOICE,
+        default='SUBMIT',
+        max_length=10,
+    )
+
+~~    review_manuscript = models.FileField(
+~~        upload_to=get_review_manuscript_full_path,
+~~        blank=True,
+~~    )
+
+
+## ... source file continues with no further examples ...
+```
+
+
+## Example 2 from wagtail
+[wagtail](https://github.com/wagtail/wagtail)
+([project website](https://wagtail.io/)) is a fantastic
+[Django](/django.html)-based CMS with code that is open source
+under the
+[BSD 3-Clause "New" or "Revised" License](https://github.com/wagtail/wagtail/blob/master/LICENSE).
+
+[**wagtail / wagtail / images / signal_handlers.py**](https://github.com/wagtail/wagtail/blob/master/wagtail/images/signal_handlers.py)
+
+```python
+from django.conf import settings
+~~from django.db import transaction
+from django.db.models.signals import post_delete, pre_save
+
+from wagtail.images import get_image_model
+
+
+~~def post_delete_file_cleanup(instance, **kwargs):
+~~    # Pass false so FileField doesn't save the model.
+~~    transaction.on_commit(lambda: instance.file.delete(False))
+
+
+def pre_save_image_feature_detection(instance, **kwargs):
+    if getattr(settings, 'WAGTAILIMAGES_FEATURE_DETECTION_ENABLED', False):
+        # Make sure the image doesn't already have a focal point
+        if not instance.has_focal_point():
+            # Set the focal point
+            instance.set_focal_point(instance.get_suggested_focal_point())
+
+
+def register_signal_handlers():
+    Image = get_image_model()
+    Rendition = Image.get_rendition_model()
+
+    pre_save.connect(pre_save_image_feature_detection, sender=Image)
+    post_delete.connect(post_delete_file_cleanup, sender=Image)
+    post_delete.connect(post_delete_file_cleanup, sender=Rendition)
+
+```
+
diff --git a/content/pages/meta/00-change-log.markdown b/content/pages/meta/00-change-log.markdown
@@ -16,6 +16,10 @@ on GitHub.
 
 ## 2019
 ### October
+* Added new Django code example pages:
+    * [django.db.models FileField](/django-db-models-filefield-examples.html)
+* Rewrote some parts of the [Python 2 or 3](/python-2-or-3.html) page to
+  make it more clear that 3 is now the mandatory way to get started.
 * Updated [best videos](/best-python-videos.html) page with new EuroPython links.
 
 ### September
diff --git a/theme/templates/table-of-contents.html b/theme/templates/table-of-contents.html
@@ -252,6 +252,7 @@ <h4 class="bp">django.db.models
  <a href="/django-db-models-charfield-examples.html">CharField</a>,
  <a href="/django-db-models-datefield-examples.html">DateField</a>,
  <a href="/django-db-models-datetimefield-examples.html">DateTimeField</a>,
+ <a href="/django-db-models-filefield-examples.html">FileField</a>,
  <a href="/django-db-models-integerfield-examples.html">IntegerField</a>,
  <a href="/django-db-models-model-examples.html">Model</a>,
  <a href="/django-db-models-textfield-examples.html">TextField</a>
