Proof of concept

.gitignore

@@ -0,0 +1,2 @@
+__pycache__
+*.pyc

byostorage/__init__.py

@@ -1 +1,2 @@
-__VERSION__ = 0.1
+__version__ = 0.1
+default_app_config = 'byostorage.apps.BYOStorageConfig'

byostorage/apps.py

@@ -1,6 +1,6 @@
 from django.apps import AppConfig
 
 
-class ByostorageConfig(AppConfig):
+class BYOStorageConfig(AppConfig):
     name = 'byostorage'
     verbose_name = 'Bring your own storage'

byostorage/local_settings.py

@@ -0,0 +1,6 @@
+INSTALLED_APPS = [
+    'django.contrib.auth',
+    'django.contrib.contenttypes',
+    'byostorage'
+]
+SECRET_KEY = 'shh!'

byostorage/migrations/0002_auto_20210311_1826.py

@@ -0,0 +1,18 @@
+# Generated by Django 3.1.7 on 2021-03-11 18:26
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('byostorage', '0001_initial'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='userstorage',
+            name='storage',
+            field=models.CharField(choices=[], help_text='Storage class for this instance', max_length=255),
+        ),
+    ]

byostorage/migrations/0003_auto_20210311_1917.py

@@ -0,0 +1,23 @@
+# Generated by Django 3.1.7 on 2021-03-11 19:17
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('byostorage', '0002_auto_20210311_1826'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='userstorage',
+            name='name',
+            field=models.SlugField(help_text='Storage tag', max_length=20, unique=True),
+        ),
+        migrations.AlterField(
+            model_name='userstorage',
+            name='storage',
+            field=models.CharField(choices=[('django.core.files.storage.FileSystemStorage', 'django.core.files.storage.FileSystemStorage')], help_text='Storage class for this instance', max_length=255),
+        ),
+    ]

byostorage/models.py

@@ -1,13 +1,34 @@
+from django.conf import settings
 from django.db import models
 from django.core.files.storage import get_storage_class
 import json
 
+STORAGE_CLASSES = getattr(settings, 'STORAGE_CLASSES', [])
+
+STORAGE_CLASSES.extend([
+    'django.core.files.storage.FileSystemStorage',
+])
+
+try:
+    import storages
+    STORAGE_CLASSES.append('storages.backends.s3boto3.S3Boto3Storage')
+except ImportError:
+    pass
+
+STORAGE_CLASS_OPTIONS = [ (x, x) for x in STORAGE_CLASSES ]
+
 class UserStorage(models.Model):
     """ A user defined storage
     """
-    owner = models.ForeignKey('auth.User', on_delete=models.CASCADE, null=True, blank=True)
-    name = models.SlugField(max_length=20, help_text="Storage tag")
-    storage = models.CharField(max_length=255, help_text="Storage class for this instance")
+    owner = models.ForeignKey('auth.User',
+            on_delete=models.CASCADE,
+            null=True, blank=True)
+    name = models.SlugField(max_length=20,
+            unique=True,
+            help_text="Storage tag")
+    storage = models.CharField(max_length=255,
+            choices=STORAGE_CLASS_OPTIONS,
+            help_text="Storage class for this instance")
     settings_data = models.TextField(help_text="JSON dict with key/value settings")
 
     def instance(self):
@@ -15,4 +36,14 @@ class UserStorage(models.Model):
 
     @property
     def settings(self):
-        return json.loads(self.settings_data)
+        if not self.settings_data:
+            return {}
+        return json.loads(self.settings_data)
+
+    def save(self, *args, **kwargs):
+        # check the settings are valid
+        self.settings
+        super(UserStorage, self).save(*args, **kwargs)
+
+    def __str__(self):
+        return self.name

byostorage/storage.py

@@ -1,4 +1,9 @@
 from django.core.files.storage import Storage
+from django.conf import settings
+
+'''
+TODO: Create a signal to remove instances from cache if modified
+'''
 
 class MultiStorage(Storage):
     ''' Django storage class that proxies multiple storage classes.
@@ -17,21 +22,51 @@ class MultiStorage(Storage):
         return self._cache[name]
 
     def split(self, name):
-        return name.split(":", 1)
-
-    def _open(self, name, mode='rb'):
-        storage, p = self.split(name)
-        return self.get_storage(storage)._open(p, mode)
+        return name.split("/", 1)
 
     def _proxy(self, method, name, *args, **kwargs):
+        print('PROXY', method, name, *args, **kwargs)
         storage, p = self.split(name)
-        sname = getattr(self.get_storage(storage), method)(name, *args, **kwargs)
-        if sname is not None:
-            return f"{storage}:{sname}"
+        result =  getattr(self.get_storage(storage), method)(p, *args, **kwargs)
+        print("RESULT", result)
+        return result
 
+    def _proxy_name(self, method, name, *args, **kwargs):
+        print('PROXY_NAME', method, name, *args, **kwargs)
+        storage, p = self.split(name)
+        result = getattr(self.get_storage(storage), method)(p, *args, **kwargs)
+        print("RESULT", result)
+        return f"{storage}/{result}"
+
+    def _open(self, name, mode='rb'):
+        return self._proxy('_open', name, mode)
 
     def _save(self, name, content, max_length=None):
-        return self._proxy('save', name, content, max_length)
+        return self._proxy_name('_save', name, content, max_length)
+
+    def exists(self, name):
+        return self._proxy('exists', name)
+
+    def delete(self, name):
+        return self._proxy('delete', name)
+
+    def url(self, name):
+        return self._proxy('url', name)
+
+    def get_accessed_time(self, name):
+        return self._proxy('get_accessed_time', name)
+
+    def get_alternative_name(self, file_root, file_ext):
+        return self._proxy_name('get_alternative_name', file_root, file_ext)
+
+    def get_available_name(self, name, max_length=None):
+        return self._proxy_name('get_available_name', name, max_length)
+
+    def get_modified_time(self, name):
+        return self._proxy('get_modified_time', name)
+
+    def get_valid_name(self, name):
+        return self._proxy_name('get_valid_name', name)
 
 class BYOStorage(MultiStorage):
     ''' Database driven Bring-Your-Own-Storage

manage.py

@@ -0,0 +1,11 @@
+#!/usr/bin/env python
+import sys, os
+
+
+INSTALLED_APPS = ['byostorage']
+
+if __name__ == "__main__":
+    from django.core.management import execute_from_command_line
+
+    os.environ.setdefault('DJANGO_SETTINGS_MODULE', 'byostorage.local_settings')
+    execute_from_command_line(sys.argv)