added -o option to scrapy crawl, a convenient shortcut for using feed…

… exports

docs/faq.rst

@@ -197,15 +197,15 @@ Simplest way to dump all my scraped items into a JSON/CSV/XML file?
 
 To dump into a JSON file::
 
-    scrapy crawl myspider -s FEED_URI=items.json -s FEED_FORMAT=json
+    scrapy crawl myspider -o items.json -t json
 
 To dump into a CSV file::
 
-    scrapy crawl myspider -s FEED_URI=items.csv -s FEED_FORMAT=csv
+    scrapy crawl myspider -o items.csv -t csv
 
 To dump into a XML file::
 
-    scrapy crawl myspider -s FEED_URI=items.xml -s FEED_FORMAT=xml
+    scrapy crawl myspider -o items.xml -t xml
 
 For more information see :ref:`topics-feed-exports`
 

docs/intro/overview.rst

@@ -161,7 +161,7 @@ Run the spider to extract the data
 Finally, we'll run the spider to crawl the site an output file
 ``scraped_data.json`` with the scraped data in JSON format::
 
-    scrapy crawl mininova.org -s FEED_URI=scraped_data.json -s FEED_FORMAT=json
+    scrapy crawl mininova.org -o scraped_data.json -t json
 
 This uses :ref:`feed exports <topics-feed-exports>` to generate the JSON file.
 You can easily change the export format (XML or CSV, for example) or the

docs/intro/tutorial.rst

@@ -420,7 +420,7 @@ Storing the scraped data
 The simplest way to store the scraped data is by using the :ref:`Feed exports
 <topics-feed-exports>`, with the following command::
 
-    scrapy crawl dmoz -s FEED_URI=items.json -s FEED_FORMAT=json
+    scrapy crawl dmoz -o items.json -t json
 
 That will generate a ``items.json`` file containing all scraped items,
 serialized in `JSON`_.

scrapy/commands/crawl.py

@@ -16,13 +16,20 @@ def add_options(self, parser):
         ScrapyCommand.add_options(self, parser)
         parser.add_option("-a", dest="spargs", action="append", default=[], metavar="NAME=VALUE", \
             help="set spider argument (may be repeated)")
+        parser.add_option("-o", "--output", metavar="FILE", \
+            help="store scraped items into FILE (using feed exports)")
+        parser.add_option("-t", "--output-format", metavar="FORMAT", default="jsonlines", \
+            help="format to use in feed exports (default: %default)")
 
     def process_options(self, args, opts):
         ScrapyCommand.process_options(self, args, opts)
         try:
             opts.spargs = arglist_to_dict(opts.spargs)
         except ValueError:
             raise UsageError("Invalid -a value, use -a NAME=VALUE", print_help=False)
+        if opts.output:
+            self.settings.overrides['FEED_URI'] = opts.output
+            self.settings.overrides['FEED_FORMAT'] = opts.output_format
 
     def run(self, args, opts):
         if len(args) < 1: