From d9cad3036e33c9fa9c0a72ae9759c3599bcb0cfb Mon Sep 17 00:00:00 2001
From: Roger Hunwicks <roger@tonic-solutions.com>
Date: Thu, 15 Jul 2021 15:36:53 +0200
Subject: [PATCH] Support DatabaseStorage.path for files in database - see #44

---
 binary_database_files/storage.py     | 13 ++++++++++++-
 binary_database_files/tests/tests.py | 14 ++++++++++++--
 2 files changed, 24 insertions(+), 3 deletions(-)

diff --git a/binary_database_files/storage.py b/binary_database_files/storage.py
index b918e55..c6830a0 100644
--- a/binary_database_files/storage.py
+++ b/binary_database_files/storage.py
@@ -126,7 +126,18 @@ def path(self, name):
         """
         localpath = self._path(self.get_instance_name(name))
         if not os.path.exists(localpath):
-            raise NotImplementedError
+            try:
+                # Load file from database.
+                f = models.File.objects.get_from_name(name)
+                # Automatically write the file to the filesystem
+                # if it's missing and exists in the database.
+                # This happens if we're using multiple web servers connected
+                # to a common database behind a load balancer.
+                # One user might upload a file from one web server, and then
+                # another might access if from another server.
+                utils.write_file(name, f.content)
+            except models.File.DoesNotExist:
+                raise NotImplementedError
         return localpath
 
     def exists(self, name):
diff --git a/binary_database_files/tests/tests.py b/binary_database_files/tests/tests.py
index 8a4812d..47456e9 100644
--- a/binary_database_files/tests/tests.py
+++ b/binary_database_files/tests/tests.py
@@ -322,7 +322,6 @@ class Meta:
         self.assertTrue(t1.upload.storage.exists(t1.upload.name))
         os.remove(t1.upload.path)
         self.assertTrue(t1.upload.storage.exists(t1.upload.name))
-        self.assertRaises(NotImplementedError, lambda t1: t1.upload.path, t1)
         data2 = b"22222222"
         open(os.path.join(tmpdir, "dummy.txt"), "wb").write(data2)
         t2 = Location2Thing.objects.create(
@@ -330,7 +329,6 @@ class Meta:
         )
         os.remove(t2.upload.path)
         self.assertTrue(t2.upload.storage.exists(t2.upload.name))
-        self.assertRaises(NotImplementedError, lambda t2: t2.upload.path, t2)
         self.assertEqual(File.objects.count(), 2)
         self.assertEqual(Location2Thing.objects.get(pk=t2.pk).upload.file.read(), data2)
         self.assertEqual(Location1Thing.objects.get(pk=t1.pk).upload.file.read(), data1)
@@ -405,6 +403,18 @@ def test_reading_file(self):
         self.assertEqual(response["content-type"], "text/plain")
         self.assertEqual(response["content-length"], "10")
 
+    def test_path_for_file_from_database(self):
+        call_command("loaddata", "test_files.json")
+        self.assertEqual(File.objects.count(), 1)
+        test_fqfn = os.path.join(DIR, "media", "1.txt")
+        os.remove(test_fqfn)
+        # File only exists in the database at this point
+        self.assertFalse(os.path.exists(test_fqfn))
+        storage = DatabaseStorage()
+        self.assertEqual(storage.path("1.txt"), test_fqfn)
+        # File now exists in the filesystem so that it can be accessed directly
+        self.assertTrue(os.path.exists(test_fqfn))
+
     def test_serve_file_from_database(self):
         call_command("loaddata", "test_files.json")
         self.assertEqual(File.objects.count(), 1)