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

用于序列化所爬取的数据，feed exports使用Item exporters。原生支持这些格式︰

But you can also extend the supported format through the FEED_EXPORTERS setting.

JSON

JSON lines

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

Pickle

Marshal

Storages

使用feed输出时您可以通过使用 URI(通过 FEED_URI 设置) 来定义存储端。The feed exports supports multiple storage backend types which are defined by the URI scheme.

The storages backends supported out of the box are:

Some storage backends may be unavailable if the required external libraries are not available. 例如，S3只有在 botocore或boto库安装的情况下才可使用（Scrapy只支持Python 2上的boto）。

存储URI参数

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

本地文件系统

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

将feed存储在Amazon S3 。

  • URI scheme: s3
  • Example URIs:
    • s3://mybucket/path/to/export.csv
    • s3://aws_key:aws_secret@mybucket/path/to/export.csv
  • 需要的外部库：botocore或boto

The AWS credentials can be passed as user/password in the URI, or they can be passed through the following settings:

标准输出

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_ENCODING

Default: None

The encoding to be used for the feed.

If unset or set to None (default) it uses UTF-8 for everything except JSON output, which uses safe numeric encoding (\uXXXX sequences) for historic reasons.

Use utf-8 if you want UTF-8 for JSON too.

FEED_EXPORT_FIELDS

Default: None

A list of fields to export, optional. Example: FEED_EXPORT_FIELDS = ["foo", "bar", "baz"].

使用FEED_EXPORT_FIELDS选项可以定义输出的字段和它们的顺序。

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_STORE_EMPTY

Default: False

Whether to export empty feeds (ie. feeds with no items).

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. You can disable any of these backends by assigning None to their URI scheme in FEED_STORAGES. E.g., to disable the built-in FTP storage backend (without replacement), place this in your settings.py:

FEED_STORAGES = {
    'ftp': None,
}

FEED_EXPORTERS

Default: {}

包含项目支持的额外输出器(exporter)的字典。The keys are serialization formats and the values are paths to Item exporter classes.

FEED_EXPORTERS_BASE

Default:

{
    'json': 'scrapy.exporters.JsonItemExporter',
    'jsonlines': 'scrapy.exporters.JsonLinesItemExporter',
    'jl': 'scrapy.exporters.JsonLinesItemExporter',
    'csv': 'scrapy.exporters.CsvItemExporter',
    'xml': 'scrapy.exporters.XmlItemExporter',
    'marshal': 'scrapy.exporters.MarshalItemExporter',
    'pickle': 'scrapy.exporters.PickleItemExporter',
}

一个包含Scrapy支持的内置Feed Exporter的字典。You can disable any of these exporters by assigning None to their serialization format in FEED_EXPORTERS. E.g., to disable the built-in CSV exporter (without replacement), place this in your settings.py:

FEED_EXPORTERS = {
    'csv': None,
}