specific thumbnail generation view + manual refresh thumbnail generation, progress bar with error handling and thumbnail deletion

viewer/migrations/0006_file_thumbnail.py

@@ -0,0 +1,18 @@
+# Generated by Django 3.1.2 on 2020-11-01 03:11
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('viewer', '0005_serveddirectory_known_subdirectories'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='file',
+            name='thumbnail',
+            field=models.CharField(default=None, max_length=160, null=True, verbose_name='Thumbnail Filename'),
+        ),
+    ]

viewer/models.py

@@ -7,6 +7,8 @@ from django.db import models
 from django.urls import reverse
 from easy_thumbnails.alias import aliases
 
+from viewer import helpers
+
 if not aliases.get('small'):
     aliases.set('small', {'size': (150, 80), 'crop': True})
 
@@ -34,16 +36,22 @@ class ServedDirectory(models.Model):
         # TODO: Implement separate recursive file matching implementation
         # TODO: Implement RegEx filtering step
         directories = []
-        for file in os.listdir(self.path):
+        files = os.listdir(self.path)
+        for i, file in enumerate(files):
+            print(f'{i} / {len(files)}')
             file_path = os.path.join(self.path, file)
 
             if os.path.isfile(file_path):
                 # Check if the file has been entered before
+                entry: File
                 entry = self.files.filter(filename__exact=file).first()
                 if entry is None:
                     # create the file entry
                     entry = File.create(full_path=file_path, parent=self)
                     entry.save()
+                else:
+                    if entry.thumbnail is None:
+                        entry.generate_thumbnail()
             else:
                 # directory found, remember it
                 directories.append(file_path)
@@ -60,6 +68,7 @@ class File(models.Model):
     filename = models.CharField('Filename', max_length=160)
     mediatype = models.CharField('Mediatype', max_length=30)
     directory = models.ForeignKey(ServedDirectory, on_delete=models.CASCADE, related_name='files')
+    thumbnail = models.CharField('Thumbnail Filename', max_length=160, null=True, default=None)
 
     @classmethod
     def create(cls, full_path: str, parent: ServedDirectory) -> 'File':
@@ -75,6 +84,42 @@ class File(models.Model):
         """Retrieve the direct URL for a given file."""
         return reverse('file', args=(directory.id, self.filename))
 
+    def delete_thumbnail(self) -> None:
+        if self.thumbnail:
+            try:
+                os.remove(os.path.join(self.thumbs_dir, self.thumbnail))
+                self.thumbnail = None
+                self.save()
+            except FileNotFoundError:
+                pass
+
+    @property
+    def thumbnail_url(self):
+        if self.thumbnail:
+            return f'/thumbnails/{self.thumbnail}'
+        return ''
+
+    @property
+    def thumbs_dir(self):
+        return os.path.join(os.path.dirname(os.path.abspath(__file__)), 'static', 'thumbnails')
+
+    def generate_thumbnail(self) -> None:
+        #  TODO: Add django-background-task scheduling
+
+        self.delete_thumbnail()
+
+        thumb_file = f'{uuid.uuid4()}.jpeg'
+        self.thumbnail = thumb_file
+
+        # Generate thumbnail
+        try:
+            helpers.generate_thumbnail(self.path, os.path.join(self.thumbs_dir, self.thumbnail))
+        except Exception:
+            print(f'Could not thumbnail: {self.filename}')
+            self.delete_thumbnail()
+
+        self.save()
+
     @staticmethod
     def get_mediatype(path) -> str:
         """Simple media type categorization based on the given path."""

viewer/urls.py

@@ -7,6 +7,8 @@ urlpatterns = [
     path('add/', views.add, name='add'),
     path('add/submit', views.submit_new, name='add_submit'),
     path('<uuid:directory_id>/', views.browse, name='browse'),
+    path('<uuid:directory_id>/refresh', views.refresh, name='refresh'),
     path('<uuid:directory_id>/<str:file>/', views.file, name='file'),
-    path('<uuid:directory_id>/refresh', views.refresh, name='refresh')
+    path('<uuid:directory_id>/<str:file>/generate', views.generate_thumb, name='generate_thumb'),
+
 ]

viewer/views.py

@@ -4,7 +4,7 @@ from django.http import FileResponse, HttpResponseRedirect
 from django.shortcuts import render, get_object_or_404
 from django.urls import reverse
 
-from viewer.models import ServedDirectory
+from viewer.models import ServedDirectory, File
 
 
 def index(request):
@@ -93,3 +93,11 @@ def submit_new(request):
                                'message': 'The directory you specified was not a valid directory, either it doesn\'t '
                                           'exist or it isn\'t a directory.'})
     return HttpResponseRedirect(reverse('browse', args=(s.id,)))
+
+
+def generate_thumb(request, directory_id, file: str):
+    """View for regenerating a thumbnail for a specific file."""
+    directory = get_object_or_404(ServedDirectory, id=directory_id)
+    file = directory.files.filter(filename=file).first()
+    file.generate_thumbnail()
+    return HttpResponseRedirect(reverse('browse', args=(directory.id,)))