13 KiB
Downloading and processing files and images
System Message: ERROR/3 (<stdin>, line 7)
Unknown directive type "currentmodule".
.. currentmodule:: scrapy.pipelines.images
Scrapy provides reusable :doc:`item pipelines </topics/item-pipeline>` for downloading files attached to a particular item (for example, when you scrape products and also want to download their images locally). These pipelines share a bit of functionality and structure (we refer to them as media pipelines), but typically you'll either use the Files Pipeline or the Images Pipeline.
System Message: ERROR/3 (<stdin>, line 9); backlink
Unknown interpreted text role "doc".Both pipelines implement these features:
- Avoid re-downloading media that was downloaded recently
- Specifying where to store the media (filesystem directory, Amazon S3 bucket)
The Images Pipeline has a few extra functions for processing images:
- Convert all downloaded images to a common format (JPG) and mode (RGB)
- Thumbnail generation
- Check images width/height to make sure they meet a minimum constraint
The pipelines also keep an internal queue of those media URLs which are currently being scheduled for download, and connect those responses that arrive containing the same media to that queue. This avoids downloading the same media more than once when it's shared by several items.
Using the Files Pipeline
The typical workflow, when using the :class:`FilesPipeline` goes like this:
System Message: ERROR/3 (<stdin>, line 34); backlink
Unknown interpreted text role "class".In a Spider, you scrape an item and put the URLs of the desired into a file_urls field.
The item is returned from the spider and goes to the item pipeline.
When the item reaches the :class:`FilesPipeline`, the URLs in the file_urls field are scheduled for download using the standard Scrapy scheduler and downloader (which means the scheduler and downloader middlewares are reused), but with a higher priority, processing them before other pages are scraped. The item remains "locked" at that particular pipeline stage until the files have finish downloading (or fail for some reason).
System Message: ERROR/3 (<stdin>, line 42); backlink
Unknown interpreted text role "class".
When the files are downloaded, another field (files) will be populated with the results. This field will contain a list of dicts with information about the downloaded files, such as the downloaded path, the original scraped url (taken from the file_urls field) , and the file checksum. The files in the list of the files field will retain the same order of the original file_urls field. If some file failed downloading, an error will be logged and the file won't be present in the files field.
Using the Images Pipeline
Using the :class:`ImagesPipeline` is a lot like using the :class:`FilesPipeline`, except the default field names used are different: you use image_urls for the image URLs of an item and it will populate an images field for the information about the downloaded images.
System Message: ERROR/3 (<stdin>, line 61); backlink
Unknown interpreted text role "class".System Message: ERROR/3 (<stdin>, line 61); backlink
Unknown interpreted text role "class".The advantage of using the :class:`ImagesPipeline` for image files is that you can configure some extra functions like generating thumbnails and filtering the images based on their size.
System Message: ERROR/3 (<stdin>, line 66); backlink
Unknown interpreted text role "class".The Images Pipeline uses Pillow for thumbnailing and normalizing images to JPEG/RGB format, so you need to install this library in order to use it. Python Imaging Library (PIL) should also work in most cases, but it is known to cause troubles in some setups, so we recommend to use Pillow instead of PIL.
Usage example
In order to use a media pipeline first, :ref:`enable it <topics-media-pipeline-enabling>`.
System Message: ERROR/3 (<stdin>, line 83); backlink
Unknown interpreted text role "ref".Then, if a spider returns a dict with the URLs key ('file_urls' or 'image_urls', for the Files or Images Pipeline respectively), the pipeline will put the results under respective key ('files' or images').
If you prefer to use :class:`~.Item`, then define a custom item with the necessary fields, like in this example for Images Pipeline:
System Message: ERROR/3 (<stdin>, line 90); backlink
Unknown interpreted text role "class".import scrapy
class MyItem(scrapy.Item):
# ... other item fields ...
image_urls = scrapy.Field()
images = scrapy.Field()
If you need something more complex and want to override the custom pipeline behaviour, see :ref:`topics-media-pipeline-override`.
System Message: ERROR/3 (<stdin>, line 101); backlink
Unknown interpreted text role "ref".Enabling your Media Pipeline
System Message: ERROR/3 (<stdin>, line 109)
Unknown directive type "setting".
.. setting:: IMAGES_STORE
System Message: ERROR/3 (<stdin>, line 110)
Unknown directive type "setting".
.. setting:: FILES_STORE
To enable your media pipeline you must first add it to your project :setting:`ITEM_PIPELINES` setting.
System Message: ERROR/3 (<stdin>, line 112); backlink
Unknown interpreted text role "setting".For Images Pipeline, use:
ITEM_PIPELINES = {'scrapy.pipelines.images.ImagesPipeline': 1}
For Files Pipeline, use:
ITEM_PIPELINES = {'scrapy.pipelines.files.FilesPipeline': 1}
Note
You can also use both the Files and Images Pipeline at the same time.
Then, configure the target storage setting to a valid value that will be used for storing the downloaded images. Otherwise the pipeline will remain disabled, even if you include it in the :setting:`ITEM_PIPELINES` setting.
System Message: ERROR/3 (<stdin>, line 128); backlink
Unknown interpreted text role "setting".For the Files Pipeline, set the :setting:`FILES_STORE` setting:
System Message: ERROR/3 (<stdin>, line 132); backlink
Unknown interpreted text role "setting".FILES_STORE = '/path/to/valid/dir'
For the Images Pipeline, set the :setting:`IMAGES_STORE` setting:
System Message: ERROR/3 (<stdin>, line 136); backlink
Unknown interpreted text role "setting".IMAGES_STORE = '/path/to/valid/dir'
Supported Storage
File system is currently the only officially supported storage, but there is also (undocumented) support for storing files in Amazon S3.
File system storage
The files are stored using a SHA1 hash of their URLs for the file names.
For example, the following image URL:
http://www.example.com/image.jpg
Whose SHA1 hash is:
3afec3b4765f8f0a07b78f98c07b83f013567a0a
Will be downloaded and stored in the following file:
<IMAGES_STORE>/full/3afec3b4765f8f0a07b78f98c07b83f013567a0a.jpg
Where:
<IMAGES_STORE> is the directory defined in :setting:`IMAGES_STORE` setting for the Images Pipeline.
System Message: ERROR/3 (<stdin>, line 167); backlink
Unknown interpreted text role "setting".
full is a sub-directory to separate full images from thumbnails (if used). For more info see :ref:`topics-images-thumbnails`.
System Message: ERROR/3 (<stdin>, line 170); backlink
Unknown interpreted text role "ref".
Additional features
File expiration
System Message: ERROR/3 (<stdin>, line 180)
Unknown directive type "setting".
.. setting:: IMAGES_EXPIRES
System Message: ERROR/3 (<stdin>, line 181)
Unknown directive type "setting".
.. setting:: FILES_EXPIRES
The Image Pipeline avoids downloading files that were downloaded recently. To adjust this retention delay use the :setting:`FILES_EXPIRES` setting (or :setting:`IMAGES_EXPIRES`, in case of Images Pipeline), which specifies the delay in number of days:
System Message: ERROR/3 (<stdin>, line 183); backlink
Unknown interpreted text role "setting".System Message: ERROR/3 (<stdin>, line 183); backlink
Unknown interpreted text role "setting".# 90 days of delay for files expiration FILES_EXPIRES = 90 # 30 days of delay for images expiration IMAGES_EXPIRES = 30
Thumbnail generation for images
The Images Pipeline can automatically create thumbnails of the downloaded images.
System Message: ERROR/3 (<stdin>, line 202)
Unknown directive type "setting".
.. setting:: IMAGES_THUMBS
In order use this feature, you must set :setting:`IMAGES_THUMBS` to a dictionary where the keys are the thumbnail names and the values are their dimensions.
System Message: ERROR/3 (<stdin>, line 204); backlink
Unknown interpreted text role "setting".For example:
IMAGES_THUMBS = {
'small': (50, 50),
'big': (270, 270),
}
When you use this feature, the Images Pipeline will create thumbnails of the each specified size with this format:
<IMAGES_STORE>/thumbs/<size_name>/<image_id>.jpg
Where:
<size_name> is the one specified in the :setting:`IMAGES_THUMBS` dictionary keys (small, big, etc)
System Message: ERROR/3 (<stdin>, line 221); backlink
Unknown interpreted text role "setting".
<image_id> is the SHA1 hash of the image url
Example of image files stored using small and big thumbnail names:
<IMAGES_STORE>/full/63bbfea82b8880ed33cdb762aa11fab722a90a24.jpg <IMAGES_STORE>/thumbs/small/63bbfea82b8880ed33cdb762aa11fab722a90a24.jpg <IMAGES_STORE>/thumbs/big/63bbfea82b8880ed33cdb762aa11fab722a90a24.jpg
The first one is the full image, as downloaded from the site.
Filtering out small images
System Message: ERROR/3 (<stdin>, line 239)
Unknown directive type "setting".
.. setting:: IMAGES_MIN_HEIGHT
System Message: ERROR/3 (<stdin>, line 241)
Unknown directive type "setting".
.. setting:: IMAGES_MIN_WIDTH
When using the Images Pipeline, you can drop images which are too small, by specifying the minimum allowed size in the :setting:`IMAGES_MIN_HEIGHT` and :setting:`IMAGES_MIN_WIDTH` settings.
System Message: ERROR/3 (<stdin>, line 243); backlink
Unknown interpreted text role "setting".System Message: ERROR/3 (<stdin>, line 243); backlink
Unknown interpreted text role "setting".For example:
IMAGES_MIN_HEIGHT = 110 IMAGES_MIN_WIDTH = 110
Note: these size constraints don't affect thumbnail generation at all.
By default, there are no size constraints, so all images are processed.
Extending the Media Pipelines
System Message: ERROR/3 (<stdin>, line 261)
Unknown directive type "module".
.. module:: scrapy.pipelines.files :synopsis: Files Pipeline
See here the methods that you can override in your custom Files Pipeline:
System Message: ERROR/3 (<stdin>, line 268)
Unknown directive type "method".
.. method:: FilesPipeline.get_media_requests(item, info)
As seen on the workflow, the pipeline will get the URLs of the images to
download from the item. In order to do this, you can override the
:meth:`~get_media_requests` method and return a Request for each
file URL::
def get_media_requests(self, item, info):
for file_url in item['file_urls']:
yield scrapy.Request(file_url)
Those requests will be processed by the pipeline and, when they have finished
downloading, the results will be sent to the
:meth:`~item_completed` method, as a list of 2-element tuples.
Each tuple will contain ``(success, file_info_or_error)`` where:
* ``success`` is a boolean which is ``True`` if the image was downloaded
successfully or ``False`` if it failed for some reason
* ``file_info_or_error`` is a dict containing the following keys (if success
is ``True``) or a `Twisted Failure`_ if there was a problem.
* ``url`` - the url where the file was downloaded from. This is the url of
the request returned from the :meth:`~get_media_requests`
method.
* ``path`` - the path (relative to :setting:`FILES_STORE`) where the file
was stored
* ``checksum`` - a `MD5 hash`_ of the image contents
The list of tuples received by :meth:`~item_completed` is
guaranteed to retain the same order of the requests returned from the
:meth:`~get_media_requests` method.
Here's a typical value of the ``results`` argument::
[(True,
{'checksum': '2b00042f7481c7b056c4b410d28f33cf',
'path': 'full/0a79c461a4062ac383dc4fade7bc09f1384a3910.jpg',
'url': 'http://www.example.com/files/product1.pdf'}),
(False,
Failure(...))]
By default the :meth:`get_media_requests` method returns ``None`` which
means there are no files to download for the item.
System Message: ERROR/3 (<stdin>, line 315)
Unknown directive type "method".
.. method:: FilesPipeline.item_completed(results, items, info)
The :meth:`FilesPipeline.item_completed` method called when all file
requests for a single item have completed (either finished downloading, or
failed for some reason).
The :meth:`~item_completed` method must return the
output that will be sent to subsequent item pipeline stages, so you must
return (or drop) the item, as you would in any pipeline.
Here is an example of the :meth:`~item_completed` method where we
store the downloaded file paths (passed in results) in the ``file_paths``
item field, and we drop the item if it doesn't contain any files::
from scrapy.exceptions import DropItem
def item_completed(self, results, item, info):
file_paths = [x['path'] for ok, x in results if ok]
if not file_paths:
raise DropItem("Item contains no files")
item['file_paths'] = file_paths
return item
By default, the :meth:`item_completed` method returns the item.
System Message: ERROR/3 (<stdin>, line 341)
Unknown directive type "module".
.. module:: scrapy.pipelines.images :synopsis: Images Pipeline
See here the methods that you can override in your custom Images Pipeline:
The :class:`ImagesPipeline` is an extension of the :class:`FilesPipeline`, customizing the field names and adding custom behavior for images.
System Message: ERROR/3 (<stdin>, line 348); backlink
Unknown interpreted text role "class".System Message: ERROR/3 (<stdin>, line 348); backlink
Unknown interpreted text role "class".
System Message: ERROR/3 (<stdin>, line 351)
Unknown directive type "method".
.. method:: ImagesPipeline.get_media_requests(item, info) Works the same way as :meth:`FilesPipeline.get_media_requests` method, but using a different field name for image urls. Must return a Request for each image URL.
System Message: ERROR/3 (<stdin>, line 358)
Unknown directive type "method".
.. method:: ImagesPipeline.item_completed(results, items, info) The :meth:`ImagesPipeline.item_completed` method is called when all image requests for a single item have completed (either finished downloading, or failed for some reason). Works the same way as :meth:`FilesPipeline.item_completed` method, but using a different field names for storing image downloading results. By default, the :meth:`item_completed` method returns the item.
Custom Images pipeline example
Here is a full example of the Images Pipeline whose methods are examplified above:
import scrapy
from scrapy.pipelines.images import ImagesPipeline
from scrapy.exceptions import DropItem
class MyImagesPipeline(ImagesPipeline):
def get_media_requests(self, item, info):
for image_url in item['image_urls']:
yield scrapy.Request(image_url)
def item_completed(self, results, item, info):
image_paths = [x['path'] for ok, x in results if ok]
if not image_paths:
raise DropItem("Item contains no images")
item['image_paths'] = image_paths
return item