Fixed #25753 -- Made get_format() cache the formats from Django settings

django/utils/formats.py

@@ -112,32 +112,40 @@ def get_format(format_type, lang=None, use_l10n=None):
     be localized (or not), overriding the value of settings.USE_L10N.
     """
     format_type = force_str(format_type)
-    if use_l10n or (use_l10n is None and settings.USE_L10N):
-        if lang is None:
+    use_l10n = use_l10n or (use_l10n is None and settings.USE_L10N)
+    if use_l10n and lang is None:
         lang = get_language()
     cache_key = (format_type, lang)
     try:
-            cached = _format_cache[cache_key]
-            if cached is not None:
-                return cached
+        return _format_cache[cache_key]
     except KeyError:
+        pass
+
+    # The requested format_type has not been cached yet. Try to find it in any
+    # of the format_modules for the given lang if l10n is enabled. If it's not
+    # there or if l10n is disabled, fall back to the project settings.
+    val = None
+    if use_l10n:
         for module in get_format_modules(lang):
             try:
                 val = getattr(module, format_type)
+                if val is not None:
+                    break
+            except AttributeError:
+                pass
+    if val is None:
+        if format_type not in FORMAT_SETTINGS:
+            return format_type
+        val = getattr(settings, format_type)
+    elif format_type in ISO_INPUT_FORMATS.keys():
+        # If a list of input formats from one of the format_modules was
+        # retrieved, make sure the ISO_INPUT_FORMATS are in this list.
+        val = list(val)
         for iso_input in ISO_INPUT_FORMATS.get(format_type, ()):
             if iso_input not in val:
-                            if isinstance(val, tuple):
-                                val = list(val)
                 val.append(iso_input)
     _format_cache[cache_key] = val
     return val
-                except AttributeError:
-                    pass
-            _format_cache[cache_key] = None
-    if format_type not in FORMAT_SETTINGS:
-        return format_type
-    # Return the general setting by default
-    return getattr(settings, format_type)
 
 
 get_format_lazy = lazy(get_format, six.text_type, list, tuple)