url preview: Use in-memory caching in dev environment.

zerver/lib/url_preview/preview.py

@@ -1,6 +1,7 @@
 import re
 import requests
 
+from django.conf import settings
 from django.utils.encoding import smart_text
 from typing import Any, Optional, Dict
 from typing.re import Match
@@ -10,7 +11,10 @@ from zerver.lib.url_preview.oembed import get_oembed_data
 from zerver.lib.url_preview.parsers import OpenGraphParser, GenericParser
 
 
-CACHE_NAME = "database"
+# FIXME: Should we use a database cache or a memcached in production? What if
+# opengraph data is changed for a site?
+# Use an in-memory cache for development, to make it easy to develop this code
+CACHE_NAME = "database" if not settings.DEVELOPMENT else "in-memory"
 # Based on django.core.validators.URLValidator, with ftp support removed.
 link_regex = re.compile(
     r'^(?:http)s?://'  # http:// or https://

zerver/tests/test_link_embed.py

@@ -27,7 +27,11 @@ TEST_CACHES = {
     'database': {
         'BACKEND': 'django.core.cache.backends.locmem.LocMemCache',
         'LOCATION': 'url-preview',
-    }
+    },
+    'in-memory': {
+        'BACKEND': 'django.core.cache.backends.locmem.LocMemCache',
+        'LOCATION': 'url-preview',
+    },
 }
 
 @override_settings(INLINE_URL_EMBED_PREVIEW=True)

zproject/settings.py

@@ -682,6 +682,9 @@ CACHES = {
             'CULL_FREQUENCY': 10,
         }
     },
+    'in-memory': {
+        'BACKEND': 'django.core.cache.backends.locmem.LocMemCache',
+    },
 }
 
 ########################################################################