Fixed #32291 -- Added fixtures compression support to dumpdata.

django/core/management/commands/dumpdata.py

@@ -1,3 +1,5 @@
+import gzip
+import os
 import warnings
 
 from django.apps import apps
@@ -6,6 +8,18 @@ from django.core.management.base import BaseCommand, CommandError
 from django.core.management.utils import parse_apps_and_model_labels
 from django.db import DEFAULT_DB_ALIAS, router
 
+try:
+    import bz2
+    has_bz2 = True
+except ImportError:
+    has_bz2 = False
+
+try:
+    import lzma
+    has_lzma = True
+except ImportError:
+    has_lzma = False
+
 
 class ProxyModelWarning(Warning):
     pass
@@ -184,7 +198,36 @@ class Command(BaseCommand):
             if output and self.stdout.isatty() and options['verbosity'] > 0:
                 progress_output = self.stdout
                 object_count = sum(get_objects(count_only=True))
-            stream = open(output, 'w') if output else None
+            if output:
+                file_root, file_ext = os.path.splitext(output)
+                compression_formats = {
+                    '.bz2': (open, {}, file_root),
+                    '.gz': (gzip.open, {}, output),
+                    '.lzma': (open, {}, file_root),
+                    '.xz': (open, {}, file_root),
+                    '.zip': (open, {}, file_root),
+                }
+                if has_bz2:
+                    compression_formats['.bz2'] = (bz2.open, {}, output)
+                if has_lzma:
+                    compression_formats['.lzma'] = (
+                        lzma.open, {'format': lzma.FORMAT_ALONE}, output
+                    )
+                    compression_formats['.xz'] = (lzma.open, {}, output)
+                try:
+                    open_method, kwargs, file_path = compression_formats[file_ext]
+                except KeyError:
+                    open_method, kwargs, file_path = (open, {}, output)
+                if file_path != output:
+                    file_name = os.path.basename(file_path)
+                    warnings.warn(
+                        f"Unsupported file extension ({file_ext}). "
+                        f"Fixtures saved in '{file_name}'.",
+                        RuntimeWarning,
+                    )
+                stream = open_method(file_path, 'wt', **kwargs)
+            else:
+                stream = None
             try:
                 serializers.serialize(
                     format, get_objects(), indent=indent,

docs/ref/django-admin.txt

@@ -364,6 +364,17 @@ standard output.
 When this option is set and ``--verbosity`` is greater than 0 (the default), a
 progress bar is shown in the terminal.
 
+Fixtures compression
+~~~~~~~~~~~~~~~~~~~~
+
+.. versionadded:: 3.2
+
+The output file can be compressed with one of the ``bz2``, ``gz``, ``lzma``, or
+``xz`` formats by ending the filename with the corresponding extension.
+For example, to output the data as a compressed JSON file::
+
+    django-admin dumpdata -o mydata.json.gz
+
 ``flush``
 ---------
 

docs/releases/3.2.txt

@@ -338,6 +338,9 @@ Management Commands
 * :djadmin:`loaddata` now supports fixtures stored in XZ archives (``.xz``) and
   LZMA archives (``.lzma``).
 
+* :djadmin:`dumpdata` now can compress data in the ``bz2``, ``gz``, ``lzma``,
+  or ``xz`` formats.
+
 * :djadmin:`makemigrations` can now be called without an active database
   connection. In that case, check for a consistent migration history is
   skipped.

tests/fixtures/tests.py

@@ -1,3 +1,4 @@
+import gzip
 import os
 import sys
 import tempfile
@@ -80,9 +81,26 @@ class DumpDataAssertMixin:
             primary_keys=primary_keys,
         )
         if filename:
-            with open(filename) as f:
+            file_root, file_ext = os.path.splitext(filename)
+            compression_formats = {
+                '.bz2': (open, file_root),
+                '.gz': (gzip.open, filename),
+                '.lzma': (open, file_root),
+                '.xz': (open, file_root),
+                '.zip': (open, file_root),
+            }
+            if HAS_BZ2:
+                compression_formats['.bz2'] = (bz2.open, filename)
+            if HAS_LZMA:
+                compression_formats['.lzma'] = (lzma.open, filename)
+                compression_formats['.xz'] = (lzma.open, filename)
+            try:
+                open_method, file_path = compression_formats[file_ext]
+            except KeyError:
+                open_method, file_path = open, filename
+            with open_method(file_path, 'rt') as f:
                 command_output = f.read()
-            os.remove(filename)
+            os.remove(file_path)
         else:
             command_output = new_io.getvalue().strip()
         if format == "json":
@@ -492,6 +510,66 @@ class FixtureLoadingTests(DumpDataAssertMixin, TestCase):
             filename='dumpdata.json'
         )
 
+    def test_dumpdata_with_file_gzip_output(self):
+        management.call_command('loaddata', 'fixture1.json', verbosity=0)
+        self._dumpdata_assert(
+            ['fixtures'],
+            '[{"pk": 1, "model": "fixtures.category", "fields": {"description": "Latest news stories", "title": '
+            '"News Stories"}}, {"pk": 2, "model": "fixtures.article", "fields": {"headline": "Poker has no place '
+            'on ESPN", "pub_date": "2006-06-16T12:00:00"}}, {"pk": 3, "model": "fixtures.article", "fields": '
+            '{"headline": "Time to reform copyright", "pub_date": "2006-06-16T13:00:00"}}]',
+            filename='dumpdata.json.gz',
+        )
+
+    @unittest.skipUnless(HAS_BZ2, 'No bz2 library detected.')
+    def test_dumpdata_with_file_bz2_output(self):
+        management.call_command('loaddata', 'fixture1.json', verbosity=0)
+        self._dumpdata_assert(
+            ['fixtures'],
+            '[{"pk": 1, "model": "fixtures.category", "fields": {"description": "Latest news stories", "title": '
+            '"News Stories"}}, {"pk": 2, "model": "fixtures.article", "fields": {"headline": "Poker has no place '
+            'on ESPN", "pub_date": "2006-06-16T12:00:00"}}, {"pk": 3, "model": "fixtures.article", "fields": '
+            '{"headline": "Time to reform copyright", "pub_date": "2006-06-16T13:00:00"}}]',
+            filename='dumpdata.json.bz2',
+        )
+
+    @unittest.skipUnless(HAS_LZMA, 'No lzma library detected.')
+    def test_dumpdata_with_file_lzma_output(self):
+        management.call_command('loaddata', 'fixture1.json', verbosity=0)
+        self._dumpdata_assert(
+            ['fixtures'],
+            '[{"pk": 1, "model": "fixtures.category", "fields": {"description": "Latest news stories", "title": '
+            '"News Stories"}}, {"pk": 2, "model": "fixtures.article", "fields": {"headline": "Poker has no place '
+            'on ESPN", "pub_date": "2006-06-16T12:00:00"}}, {"pk": 3, "model": "fixtures.article", "fields": '
+            '{"headline": "Time to reform copyright", "pub_date": "2006-06-16T13:00:00"}}]',
+            filename='dumpdata.json.lzma',
+        )
+
+    @unittest.skipUnless(HAS_LZMA, 'No lzma library detected.')
+    def test_dumpdata_with_file_xz_output(self):
+        management.call_command('loaddata', 'fixture1.json', verbosity=0)
+        self._dumpdata_assert(
+            ['fixtures'],
+            '[{"pk": 1, "model": "fixtures.category", "fields": {"description": "Latest news stories", "title": '
+            '"News Stories"}}, {"pk": 2, "model": "fixtures.article", "fields": {"headline": "Poker has no place '
+            'on ESPN", "pub_date": "2006-06-16T12:00:00"}}, {"pk": 3, "model": "fixtures.article", "fields": '
+            '{"headline": "Time to reform copyright", "pub_date": "2006-06-16T13:00:00"}}]',
+            filename='dumpdata.json.xz',
+        )
+
+    def test_dumpdata_with_file_zip_output(self):
+        management.call_command('loaddata', 'fixture1.json', verbosity=0)
+        msg = "Unsupported file extension (.zip). Fixtures saved in 'dumpdata.json'."
+        with self.assertWarnsMessage(RuntimeWarning, msg):
+            self._dumpdata_assert(
+                ['fixtures'],
+                '[{"pk": 1, "model": "fixtures.category", "fields": {"description": "Latest news stories", "title": '
+                '"News Stories"}}, {"pk": 2, "model": "fixtures.article", "fields": {"headline": "Poker has no place '
+                'on ESPN", "pub_date": "2006-06-16T12:00:00"}}, {"pk": 3, "model": "fixtures.article", "fields": '
+                '{"headline": "Time to reform copyright", "pub_date": "2006-06-16T13:00:00"}}]',
+                filename='dumpdata.json.zip',
+            )
+
     def test_dumpdata_progressbar(self):
         """
         Dumpdata shows a progress bar on the command line when --output is set,