# The fetch Function - Google App Engine - Google Code

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# The fetch Function

The `fetch()` function makes a synchronous request to fetch a URL. This function is provided by the `google.appengine.api.urlfetch` package.

See also Asychronous Requests.

fetch(url, payload=None, method=GET, headers={}, allow_truncated=False, follow_redirects=True, deadline=None, validate_certificate=None)

  Fetches a document at the URL given in url, and returns an object containing the details of the response. See Response Objects for details about the return value.

  The fetch action is synchronous. fetch() will not return until the server responds. A slow remote server may cause your application's own request to time out.

  Arguments:

  url
    An `http` or `https` URL. If the URL is invalid, a InvalidURLError is raised.
  payload
    Body content for a `POST` or `PUT` request.
  method
    The HTTP method to use for the request. Acceptable values include `GET`, `POST`, `HEAD`, `PUT`, and `DELETE`. These values are constants provided by the package. The value can also be a string equivalent to the name of the method.
  headers
    The set of HTTP headers to include with the request, as a mapping of names and values. For security reasons, some HTTP headers cannot be modified by the application. See the URL Fetch Service overview.
  allow_truncated
    If `False` and the response data exceeds the maximum allowed response size, a ResponseTooLargeError exception is raised. If `True`, no exception is raised, and the response's `content` is truncated to the maximum size, and the response object's `content_was_truncated` attribute is set to `True`. For more information on limits, see the URL Fetch Service overview.
  follow_redirects

    If `True`, responses that are HTTP redirects are followed, up to 5 consecutive redirects. The response data is from the final location, as if the data were for the requested location. If `False`, redirects are not followed, and a redirect response is returned directly to the application, including the header information that describes the redirect.

    Warning: Cookies are not handled upon redirection. If cookie handling is needed, set follow_redirects to `False` and handle both cookies and redirects manually.

  deadline

    The maximum amount of time to wait for a response from the remote host, as a number of seconds. If the remote host does not respond in this amount of time, a DownloadError is raised.

    Time spent waiting for a request does not count toward the CPU quota for the request. It does count toward the request timer. If the app request timer expires before the URL Fetch call returns, the call is canceled.

    The deadline can be up to a maximum of 60 seconds for request handlers and 10 minutes for tasks queue and cron job handlers. If deadline is `None`, the deadline is set to 5 seconds.

  validate_certificate

    A value of `True` instructs the application to send a request to the server only if the certificate is valid and signed by a trusted CA, and also includes a hostname that matches the certificate. A value of `False` instructs the application to perform no certificate validation. A value of `None` defaults to the underlying implementation of URL Fetch. The underlying implementation currently defaults to `False`, but will default to `True` in the near future.