From f81ca786427db40b648b5bcc0e67044163215457 Mon Sep 17 00:00:00 2001
From: Thorsten <51322849+tfranzel-cashlink@users.noreply.github.com>
Date: Wed, 12 Feb 2020 20:35:54 +0100
Subject: [PATCH] Add file option to generateschema (#7130)

---
 docs/api-guide/schemas.md                       |  2 +-
 .../management/commands/generateschema.py       |  8 +++++++-
 tests/schemas/test_managementcommand.py         | 17 +++++++++++++++++
 3 files changed, 25 insertions(+), 2 deletions(-)

diff --git a/docs/api-guide/schemas.md b/docs/api-guide/schemas.md
index e33a2a611..e63fd83e6 100644
--- a/docs/api-guide/schemas.md
+++ b/docs/api-guide/schemas.md
@@ -30,7 +30,7 @@ into the commonly used YAML-based OpenAPI format.
 If your schema is static, you can use the `generateschema` management command:
 
 ```bash
-./manage.py generateschema > openapi-schema.yml
+./manage.py generateschema --file openapi-schema.yml
 ```
 
 Once you've generated a schema in this way you can annotate it with any
diff --git a/rest_framework/management/commands/generateschema.py b/rest_framework/management/commands/generateschema.py
index a7763492c..024306b65 100644
--- a/rest_framework/management/commands/generateschema.py
+++ b/rest_framework/management/commands/generateschema.py
@@ -25,6 +25,7 @@ class Command(BaseCommand):
             parser.add_argument('--format', dest="format", choices=['openapi', 'openapi-json'], default='openapi', type=str)
         parser.add_argument('--urlconf', dest="urlconf", default=None, type=str)
         parser.add_argument('--generator_class', dest="generator_class", default=None, type=str)
+        parser.add_argument('--file', dest="file", default=None, type=str)
 
     def handle(self, *args, **options):
         if options['generator_class']:
@@ -40,7 +41,12 @@ class Command(BaseCommand):
         schema = generator.get_schema(request=None, public=True)
         renderer = self.get_renderer(options['format'])
         output = renderer.render(schema, renderer_context={})
-        self.stdout.write(output.decode())
+
+        if options['file']:
+            with open(options['file'], 'wb') as f:
+                f.write(output)
+        else:
+            self.stdout.write(output.decode())
 
     def get_renderer(self, format):
         if self.get_mode() == COREAPI_MODE:
diff --git a/tests/schemas/test_managementcommand.py b/tests/schemas/test_managementcommand.py
index 6cdf7f8b1..115f871e5 100644
--- a/tests/schemas/test_managementcommand.py
+++ b/tests/schemas/test_managementcommand.py
@@ -1,4 +1,6 @@
 import io
+import os
+import tempfile
 
 import pytest
 from django.conf.urls import url
@@ -73,6 +75,21 @@ class GenerateSchemaTests(TestCase):
         out_json = yaml.safe_load(self.out.getvalue())
         assert out_json == CustomSchemaGenerator.SCHEMA
 
+    def test_writes_schema_to_file_on_parameter(self):
+        fd, path = tempfile.mkstemp()
+        try:
+            call_command('generateschema', '--file={}'.format(path), stdout=self.out)
+            # nothing on stdout
+            assert not self.out.getvalue()
+
+            call_command('generateschema', stdout=self.out)
+            expected_out = self.out.getvalue()
+            # file output identical to stdout output
+            with os.fdopen(fd) as fh:
+                assert expected_out and fh.read() == expected_out
+        finally:
+            os.remove(path)
+
     @pytest.mark.skipif(yaml is None, reason='PyYAML is required.')
     @override_settings(REST_FRAMEWORK={'DEFAULT_SCHEMA_CLASS': 'rest_framework.schemas.AutoSchema'})
     def test_coreapi_renders_default_schema_with_custom_title_url_and_description(self):