Merge pull request #2456 from elacuesta/feed_export_beautify

[MRG+1] Feed exports: beautify JSON and XML

docs/topics/exporters.rst

@@ -140,7 +140,7 @@ output examples, which assume you're exporting these two items::
 BaseItemExporter
 ----------------
 
-.. class:: BaseItemExporter(fields_to_export=None, export_empty_fields=False, encoding='utf-8')
+.. class:: BaseItemExporter(fields_to_export=None, export_empty_fields=False, encoding='utf-8', indent=0)
 
    This is the (abstract) base class for all Item Exporters. It provides
    support for common features used by all (concrete) Item Exporters, such as
@@ -149,7 +149,7 @@ BaseItemExporter
 
    These features can be configured through the constructor arguments which
    populate their respective instance attributes: :attr:`fields_to_export`,
-   :attr:`export_empty_fields`, :attr:`encoding`.
+   :attr:`export_empty_fields`, :attr:`encoding`, :attr:`indent`.
 
    .. method:: export_item(item)
 
@@ -216,6 +216,15 @@ BaseItemExporter
       encoding). Other value types are passed unchanged to the specific
       serialization library.
 
+   .. attribute:: indent
+
+      Amount of spaces used to indent the output on each level. Defaults to ``0``.
+
+      * ``indent=None`` selects the most compact representation,
+        all items in the same line with no indentation
+      * ``indent<=0`` each item on its own line, no indentation
+      * ``indent>0`` each item on its own line, indented with the provided numeric value
+
 .. highlight:: none
 
 XmlItemExporter

docs/topics/feed-exports.rst

@@ -209,6 +209,7 @@ These are the settings used for configuring the feed exports:
  * :setting:`FEED_STORE_EMPTY`
  * :setting:`FEED_EXPORT_ENCODING`
  * :setting:`FEED_EXPORT_FIELDS`
+ * :setting:`FEED_EXPORT_INDENT`
 
 .. currentmodule:: scrapy.extensions.feedexport
 
@@ -266,6 +267,22 @@ If an exporter requires a fixed set of fields (this is the case for
 is empty or None, then Scrapy tries to infer field names from the
 exported data - currently it uses field names from the first item.
 
+.. setting:: FEED_EXPORT_INDENT
+
+FEED_EXPORT_INDENT
+------------------
+
+Default: ``0``
+
+Amount of spaces used to indent the output on each level. If ``FEED_EXPORT_INDENT``
+is a non-negative integer, then array elements and object members will be pretty-printed
+with that indent level. An indent level of ``0`` (the default), or negative,
+will put each item on a new line. ``None`` selects the most compact representation.
+
+Currently implemented only by :class:`~scrapy.exporters.JsonItemExporter`
+and :class:`~scrapy.exporters.XmlItemExporter`, i.e. when you are exporting
+to ``.json`` or ``.xml``.
+
 .. setting:: FEED_STORE_EMPTY
 
 FEED_STORE_EMPTY

scrapy/exporters.py

@@ -36,6 +36,7 @@ class BaseItemExporter(object):
         self.encoding = options.pop('encoding', None)
         self.fields_to_export = options.pop('fields_to_export', None)
         self.export_empty_fields = options.pop('export_empty_fields', False)
+        self.indent = options.pop('indent', None)
         if not dont_fail and options:
             raise TypeError("Unexpected options: %s" % ', '.join(options.keys()))
 
@@ -98,21 +99,33 @@ class JsonItemExporter(BaseItemExporter):
     def __init__(self, file, **kwargs):
         self._configure(kwargs, dont_fail=True)
         self.file = file
+        # there is a small difference between the behaviour or JsonItemExporter.indent
+        # and ScrapyJSONEncoder.indent. ScrapyJSONEncoder.indent=None is needed to prevent
+        # the addition of newlines everywhere
+        json_indent = self.indent if self.indent is not None and self.indent > 0 else None
+        kwargs.setdefault('indent', json_indent)
         kwargs.setdefault('ensure_ascii', not self.encoding)
         self.encoder = ScrapyJSONEncoder(**kwargs)
         self.first_item = True
 
+    def _beautify_newline(self):
+        if self.indent is not None:
+            self.file.write(b'\n')
+
     def start_exporting(self):
-        self.file.write(b"[\n")
+        self.file.write(b"[")
+        self._beautify_newline()
 
     def finish_exporting(self):
-        self.file.write(b"\n]")
+        self._beautify_newline()
+        self.file.write(b"]")
 
     def export_item(self, item):
         if self.first_item:
             self.first_item = False
         else:
-            self.file.write(b',\n')
+            self.file.write(b',')
+            self._beautify_newline()
         itemdict = dict(self._get_serialized_fields(item))
         data = self.encoder.encode(itemdict)
         self.file.write(to_bytes(data, self.encoding))
@@ -128,33 +141,52 @@ class XmlItemExporter(BaseItemExporter):
             self.encoding = 'utf-8'
         self.xg = XMLGenerator(file, encoding=self.encoding)
 
+    def _beautify_newline(self, new_item=False):
+        if self.indent is not None and (self.indent > 0 or new_item):
+            self._xg_characters('\n')
+
+    def _beautify_indent(self, depth=1):
+        if self.indent:
+            self._xg_characters(' ' * self.indent * depth)
+
     def start_exporting(self):
         self.xg.startDocument()
         self.xg.startElement(self.root_element, {})
+        self._beautify_newline(new_item=True)
 
     def export_item(self, item):
+        self._beautify_indent(depth=1)
         self.xg.startElement(self.item_element, {})
+        self._beautify_newline()
         for name, value in self._get_serialized_fields(item, default_value=''):
-            self._export_xml_field(name, value)
+            self._export_xml_field(name, value, depth=2)
+        self._beautify_indent(depth=1)
         self.xg.endElement(self.item_element)
+        self._beautify_newline(new_item=True)
 
     def finish_exporting(self):
         self.xg.endElement(self.root_element)
         self.xg.endDocument()
 
-    def _export_xml_field(self, name, serialized_value):
+    def _export_xml_field(self, name, serialized_value, depth):
+        self._beautify_indent(depth=depth)
         self.xg.startElement(name, {})
         if hasattr(serialized_value, 'items'):
+            self._beautify_newline()
             for subname, value in serialized_value.items():
-                self._export_xml_field(subname, value)
+                self._export_xml_field(subname, value, depth=depth+1)
+            self._beautify_indent(depth=depth)
         elif is_listlike(serialized_value):
+            self._beautify_newline()
             for value in serialized_value:
-                self._export_xml_field('value', value)
+                self._export_xml_field('value', value, depth=depth+1)
+            self._beautify_indent(depth=depth)
         elif isinstance(serialized_value, six.text_type):
             self._xg_characters(serialized_value)
         else:
             self._xg_characters(str(serialized_value))
         self.xg.endElement(name)
+        self._beautify_newline()
 
     # Workaround for http://bugs.python.org/issue17606
     # Before Python 2.7.4 xml.sax.saxutils required bytes;

scrapy/extensions/feedexport.py

@@ -172,6 +172,9 @@ class FeedExporter(object):
         self.store_empty = settings.getbool('FEED_STORE_EMPTY')
         self._exporting = False
         self.export_fields = settings.getlist('FEED_EXPORT_FIELDS') or None
+        self.indent = None
+        if settings.get('FEED_EXPORT_INDENT') is not None:
+            self.indent = settings.getint('FEED_EXPORT_INDENT')
         uripar = settings['FEED_URI_PARAMS']
         self._uripar = load_object(uripar) if uripar else lambda x, y: None
 
@@ -188,7 +191,7 @@ class FeedExporter(object):
         storage = self._get_storage(uri)
         file = storage.open(spider)
         exporter = self._get_exporter(file, fields_to_export=self.export_fields,
-            encoding=self.export_encoding)
+            encoding=self.export_encoding, indent=self.indent)
         if self.store_empty:
             exporter.start_exporting()
             self._exporting = True

scrapy/settings/default_settings.py

@@ -161,6 +161,7 @@ FEED_EXPORTERS_BASE = {
     'marshal': 'scrapy.exporters.MarshalItemExporter',
     'pickle': 'scrapy.exporters.PickleItemExporter',
 }
+FEED_EXPORT_INDENT = 0
 
 FILES_STORE_S3_ACL = 'private'
 

tests/test_feedexport.py

@@ -319,14 +319,14 @@ class FeedExportTest(unittest.TestCase):
     @defer.inlineCallbacks
     def test_export_no_items_store_empty(self):
         formats = (
-            ('json', b'[\n\n]'),
+            ('json', b'[]'),
             ('jsonlines', b''),
             ('xml', b'<?xml version="1.0" encoding="utf-8"?>\n<items></items>'),
             ('csv', b''),
         )
 
         for fmt, expctd in formats:
-            settings = {'FEED_FORMAT': fmt, 'FEED_STORE_EMPTY': True}
+            settings = {'FEED_FORMAT': fmt, 'FEED_STORE_EMPTY': True, 'FEED_EXPORT_INDENT': None}
             data = yield self.exported_no_data(settings)
             self.assertEqual(data, expctd)
 
@@ -425,25 +425,177 @@ class FeedExportTest(unittest.TestCase):
         header = ['foo']
 
         formats = {
-            'json': u'[\n{"foo": "Test\\u00d6"}\n]'.encode('utf-8'),
+            'json': u'[{"foo": "Test\\u00d6"}]'.encode('utf-8'),
             'jsonlines': u'{"foo": "Test\\u00d6"}\n'.encode('utf-8'),
             'xml': u'<?xml version="1.0" encoding="utf-8"?>\n<items><item><foo>Test\xd6</foo></item></items>'.encode('utf-8'),
             'csv': u'foo\r\nTest\xd6\r\n'.encode('utf-8'),
         }
 
-        for format in formats:
-            settings = {'FEED_FORMAT': format}
+        for format, expected in formats.items():
+            settings = {'FEED_FORMAT': format, 'FEED_EXPORT_INDENT': None}
             data = yield self.exported_data(items, settings)
-            self.assertEqual(formats[format], data)
+            self.assertEqual(expected, data)
 
         formats = {
-            'json': u'[\n{"foo": "Test\xd6"}\n]'.encode('latin-1'),
+            'json': u'[{"foo": "Test\xd6"}]'.encode('latin-1'),
             'jsonlines': u'{"foo": "Test\xd6"}\n'.encode('latin-1'),
             'xml': u'<?xml version="1.0" encoding="latin-1"?>\n<items><item><foo>Test\xd6</foo></item></items>'.encode('latin-1'),
             'csv': u'foo\r\nTest\xd6\r\n'.encode('latin-1'),
         }
 
-        for format in formats:
-            settings = {'FEED_FORMAT': format, 'FEED_EXPORT_ENCODING': 'latin-1'}
+        settings = {'FEED_EXPORT_INDENT': None, 'FEED_EXPORT_ENCODING': 'latin-1'}
+        for format, expected in formats.items():
+            settings['FEED_FORMAT'] = format
             data = yield self.exported_data(items, settings)
-            self.assertEqual(formats[format], data)
+            self.assertEqual(expected, data)
+
+    @defer.inlineCallbacks
+    def test_export_indentation(self):
+        items = [
+            {'foo': ['bar']},
+            {'key': 'value'},
+        ]
+
+        test_cases = [
+            # JSON
+            {
+                'format': 'json',
+                'indent': None,
+                'expected': b'[{"foo": ["bar"]},{"key": "value"}]',
+            },
+            {
+                'format': 'json',
+                'indent': -1,
+                'expected': b"""[
+{"foo": ["bar"]},
+{"key": "value"}
+]""",
+            },
+            {
+                'format': 'json',
+                'indent': 0,
+                'expected': b"""[
+{"foo": ["bar"]},
+{"key": "value"}
+]""",
+            },
+            {
+                'format': 'json',
+                'indent': 2,
+                'expected': b"""[
+{
+  "foo": [
+    "bar"
+  ]
+},
+{
+  "key": "value"
+}
+]""",
+            },
+            {
+                'format': 'json',
+                'indent': 4,
+                'expected': b"""[
+{
+    "foo": [
+        "bar"
+    ]
+},
+{
+    "key": "value"
+}
+]""",
+            },
+            {
+                'format': 'json',
+                'indent': 5,
+                'expected': b"""[
+{
+     "foo": [
+          "bar"
+     ]
+},
+{
+     "key": "value"
+}
+]""",
+            },
+
+            # XML
+            {
+                'format': 'xml',
+                'indent': None,
+                'expected': b"""<?xml version="1.0" encoding="utf-8"?>
+<items><item><foo><value>bar</value></foo></item><item><key>value</key></item></items>""",
+            },
+            {
+                'format': 'xml',
+                'indent': -1,
+                'expected': b"""<?xml version="1.0" encoding="utf-8"?>
+<items>
+<item><foo><value>bar</value></foo></item>
+<item><key>value</key></item>
+</items>""",
+            },
+            {
+                'format': 'xml',
+                'indent': 0,
+                'expected': b"""<?xml version="1.0" encoding="utf-8"?>
+<items>
+<item><foo><value>bar</value></foo></item>
+<item><key>value</key></item>
+</items>""",
+            },
+            {
+                'format': 'xml',
+                'indent': 2,
+                'expected': b"""<?xml version="1.0" encoding="utf-8"?>
+<items>
+  <item>
+    <foo>
+      <value>bar</value>
+    </foo>
+  </item>
+  <item>
+    <key>value</key>
+  </item>
+</items>""",
+            },
+            {
+                'format': 'xml',
+                'indent': 4,
+                'expected': b"""<?xml version="1.0" encoding="utf-8"?>
+<items>
+    <item>
+        <foo>
+            <value>bar</value>
+        </foo>
+    </item>
+    <item>
+        <key>value</key>
+    </item>
+</items>""",
+            },
+            {
+                'format': 'xml',
+                'indent': 5,
+                'expected': b"""<?xml version="1.0" encoding="utf-8"?>
+<items>
+     <item>
+          <foo>
+               <value>bar</value>
+          </foo>
+     </item>
+     <item>
+          <key>value</key>
+     </item>
+</items>""",
+            },
+        ]
+
+        for row in test_cases:
+            settings = {'FEED_FORMAT': row['format'], 'FEED_EXPORT_INDENT': row['indent']}
+            data = yield self.exported_data(items, settings)
+            print(row['format'], row['indent'])
+            self.assertEqual(row['expected'], data)