Grab Quickstart¶
Before working with Grab ensure that you have the latest version. The recommended way of installing Grab is by using pip:
pip install -U Grab
You should also manually install the lxml and pycurl libraries.
Let’s get started with some simple examples.
Make a request¶
First, you need to import the Grab class:
>>> from grab import Grab
Then you can build Grab instances and make simple network requests:
>>> from grab import Grab
>>> g = Grab()
>>> resp = g.go('http://livejournal.com/')
Now, we have a Response object which provides an interface to the response’s content, cookies, headers and other things.
We’ve just made a GET request. To make other request types, you need to configure the Grab instance via the setup method with the method argument:
>>> g.setup(method='put')
>>> g.setup(method='delete')
>>> g.setup(method='options')
>>> g.setup(method='head')
Let’s see a small example of HEAD request:
>>> g = Grab()
>>> g.setup(method='head')
>>> resp = g.go('http://google.com/robots.txt')
>>> print len(resp.body)
0
>>> print resp.headers['Content-Length']
1776
Creating POST requests¶
When you build site scrapers or work with network APIs it is a common task to create POST requests. You can build POST request using the post option:
>>> g = Grab()
>>> g.setup(post={'username': 'Root', 'password': 'asd7DD&*ssd'})
>>> g.go('http://example.com/log-in-form')
Another common task is to get a web form, fill it in and submit it. Grab provides an easy way to work with forms:
>>> g = Grab()
>>> g.go('http://example/com/log-in')
>>> g.set_input('username', 'Foo')
>>> g.set_input('password', 'Bar')
>>> g.submit()
When you call submit, Grab will build a POST request using the values passed in via set_input. If you did not specify values for some form elements then Grab will use their default values.
Grab also provides an interface to upload files:
>>> from grab import Grab, UploadFile
>>> g = Grab()
>>> g.setup(post={'name': 'Flower', 'file': UploadFile('/path/to/image.png')})
>>> g.submit()
Also you can upload files via the form API:
>>> from grab import Grab, UloadFile
>>> g = Grab()
>>> g.go('http://example.com/some-form')
>>> g.set_input('name', 'A flower')
>>> g.set_input('file', UploadFile('/path/to/image.png'))
>>> g.submit()
Response Content¶
Consider a simple page retrieving example:
>>> g = Grab()
>>> resp = g.go('http://google.com/')
To get the response content as unicode use:
>>> resp.unicode_body()
Note that grab will automatically detect the character set (charset for short) of the response content and convert it to unicode. You can detected the charset with:
>>> resp.charset
If you need the original response body then use:
>>> resp.body
Original content is useful if you need to save a binary file (e.g. an image):
>>> resp = g.go('http://example.com/some-log.png')
>>> open('logo.png', 'w').write(resp.body)
The gzip and deflate encodings are automatically decoded.
Response Status Code¶
TO BE CONTINUED