Feed exports¶
New in version 0.10.
One of the most frequently required features when implementing scrapers is being able to store the scraped data properly and, quite often, that means generating an “export file” with the scraped data (commonly called “export feed”) to be consumed by other systems.
Scrapy provides this functionality out of the box with the Feed Exports, which allows you to generate a feed with the scraped items, using multiple serialization formats and storage backends.
Serialization formats¶
For serializing the scraped data, the feed exports use the Item exporters. These formats are supported out of the box:
But you can also extend the supported format through the
FEED_EXPORTERS
setting.
JSON¶
FEED_FORMAT
:json
- Exporter used:
JsonItemExporter
- See this warning if you’re using JSON with large feeds.
JSON lines¶
FEED_FORMAT
:jsonlines
- Exporter used:
JsonLinesItemExporter
CSV¶
FEED_FORMAT
:csv
- Exporter used:
CsvItemExporter
- To specify columns to export and their order use
FEED_EXPORT_FIELDS
. Other feed exporters can also use this option, but it is important for CSV because unlike many other export formats CSV uses a fixed header.
XML¶
FEED_FORMAT
:xml
- Exporter used:
XmlItemExporter
Pickle¶
FEED_FORMAT
:pickle
- Exporter used:
PickleItemExporter
Marshal¶
FEED_FORMAT
:marshal
- Exporter used:
MarshalItemExporter
Storages¶
When using the feed exports you define where to store the feed using a URI
(through the FEED_URI
setting). The feed exports supports multiple
storage backend types which are defined by the URI scheme.
The storages backends supported out of the box are:
- Local filesystem
- FTP
- S3 (requires boto)
- Standard output
Some storage backends may be unavailable if the required external libraries are not available. For example, the S3 backend is only available if the boto library is installed.
Storage URI parameters¶
The storage URI can also contain parameters that get replaced when the feed is being created. These parameters are:
%(time)s
- gets replaced by a timestamp when the feed is being created%(name)s
- gets replaced by the spider name
Any other named parameter gets replaced by the spider attribute of the same
name. For example, %(site_id)s
would get replaced by the spider.site_id
attribute the moment the feed is being created.
Here are some examples to illustrate:
- Store in FTP using one directory per spider:
ftp://user:password@ftp.example.com/scraping/feeds/%(name)s/%(time)s.json
- Store in S3 using one directory per spider:
s3://mybucket/scraping/feeds/%(name)s/%(time)s.json
Storage backends¶
Local filesystem¶
The feeds are stored in the local filesystem.
- URI scheme:
file
- Example URI:
file:///tmp/export.csv
- Required external libraries: none
Note that for the local filesystem storage (only) you can omit the scheme if
you specify an absolute path like /tmp/export.csv
. This only works on Unix
systems though.
FTP¶
The feeds are stored in a FTP server.
- URI scheme:
ftp
- Example URI:
ftp://user:pass@ftp.example.com/path/to/export.csv
- Required external libraries: none
S3¶
The feeds are stored on Amazon S3.
- URI scheme:
s3
- Example URIs:
s3://mybucket/path/to/export.csv
s3://aws_key:aws_secret@mybucket/path/to/export.csv
- Required external libraries: boto
The AWS credentials can be passed as user/password in the URI, or they can be passed through the following settings:
Standard output¶
The feeds are written to the standard output of the Scrapy process.
- URI scheme:
stdout
- Example URI:
stdout:
- Required external libraries: none
Settings¶
These are the settings used for configuring the feed exports:
FEED_URI¶
Default: None
The URI of the export feed. See Storage backends for supported URI schemes.
This setting is required for enabling the feed exports.
FEED_FORMAT¶
The serialization format to be used for the feed. See Serialization formats for possible values.
FEED_EXPORT_FIELDS¶
Default: None
A list of fields to export, optional.
Example: FEED_EXPORT_FIELDS = ["foo", "bar", "baz"]
.
Use FEED_EXPORT_FIELDS option to define fields to export and their order.
When FEED_EXPORT_FIELDS is empty or None (default), Scrapy uses fields
defined in dicts or Item
subclasses a spider is yielding.
If an exporter requires a fixed set of fields (this is the case for CSV export format) and FEED_EXPORT_FIELDS is empty or None, then Scrapy tries to infer field names from the exported data - currently it uses field names from the first item.
FEED_STORAGES¶
Default:: {}
A dict containing additional feed storage backends supported by your project. The keys are URI schemes and the values are paths to storage classes.
FEED_STORAGES_BASE¶
Default:
{
'': 'scrapy.extensions.feedexport.FileFeedStorage',
'file': 'scrapy.extensions.feedexport.FileFeedStorage',
'stdout': 'scrapy.extensions.feedexport.StdoutFeedStorage',
's3': 'scrapy.extensions.feedexport.S3FeedStorage',
'ftp': 'scrapy.extensions.feedexport.FTPFeedStorage',
}
A dict containing the built-in feed storage backends supported by Scrapy.
FEED_EXPORTERS¶
Default:: {}
A dict containing additional exporters supported by your project. The keys are URI schemes and the values are paths to Item exporter classes.
FEED_EXPORTERS_BASE¶
Default:
FEED_EXPORTERS_BASE = {
'json': 'scrapy.exporters.JsonItemExporter',
'jsonlines': 'scrapy.exporters.JsonLinesItemExporter',
'csv': 'scrapy.exporters.CsvItemExporter',
'xml': 'scrapy.exporters.XmlItemExporter',
'marshal': 'scrapy.exporters.MarshalItemExporter',
}
A dict containing the built-in feed exporters supported by Scrapy.