When you create a Request object you can pass a dictionary of headers in. The following example makes the same request as above, but identifies itself as a version of Internet Explorer 4. The response also has two useful methods. See the section on info and geturl which comes after we have a look at what happens when things go wrong.
The exception classes are exported from the urllib. Sometimes the status code indicates that the server is unable to fulfil the request. Because the default handlers handle redirects codes in the range , and codes in the — range indicate success, you will usually only see error codes in the — range.
The dictionary is reproduced here for convenience. When an error is raised the server responds by returning an HTTP error code and an error page. This means that as well as the code attribute, it also has read, geturl, and info, methods as returned by the urllib.
I prefer the second approach. The response returned by urlopen or the HTTPError instance has two useful methods info and geturl and is defined in the module urllib. This is useful because urlopen or the opener object used may have followed a redirect.
It is currently an http. HTTPMessage instance. When you fetch a URL you use an opener an instance of the perhaps confusingly-named urllib. Normally we have been using the default opener - via urlopen - but you can create custom openers. Openers use handlers. You will want to create openers if you want to fetch URLs with specific handlers installed, for example to get an opener that handles cookies, or to get an opener that does not handle redirections.
To create an opener, instantiate an OpenerDirector , and then call. Other sorts of handlers you might want to can handle proxies, authentication, and other common but slightly specialised situations.
For more precise control, you may want to instantiate and use a Request object directly. As the examples above illustrate, the default User-agent header value is made up of the constant Python-urllib , followed by the Python interpreter version. Using a custom agent also allows them to control crawlers using a robots. The last line of the output shows our custom value. You can set the outgoing data on the Request to post it to the server.
Each call replaces the previous data. Encoding files for upload requires a little more work than simple forms. Allowed characters are any alphabetic characters, numerals, and a few special characters that have meaning in the URL string. This section of error handling is based on the information from Voidspace. When an error is raised the server responds by returning an HTTP error code and an error page. This means that as well as the code attribute, it also has read, geturl, and info, methods.
Over 15 hours of video content with guided instruction for beginners. These are now a part of the urllib package in Python 3. The current version of urllib is made up of the following modules:. We will be covering each part individually except for urllib. The official documentation actually recommends that you might want to check out the 3rd party library, requests , for a higher-level HTTP client interface.
However, we believe that it can be useful to know how to open URLs and interact with them without using a 3rd party and it may also help you appreciate why the requests package is so popular.
Note : This urllib. In the earlier snippet, we first import the urllib. Next, we create a variable url that contains the path of the file to be downloaded. Keep in mind that you can pass any filename as the second parameter and that is the location and name that your file will have, assuming you have the correct permissions. The open method accepts two parameters, the path to the local file and the mode in which data will be written.
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