4.5.3.1 Request Methods
Description: Request Methods
Keywords: modpython

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4.5.3.1 Request Methods

`add_common_vars`( | )

  Calls the Apache `ap_add_common_vars()` function. After a call to this method, `req.subprocess_env` will contain a lot of CGI information.

`add_handler`( | htype, handler[, dir])

  Allows dynamic handler registration. htype is a string containing the name of any of the apache request (but not filter or connection) handler directives, e.g. "`PythonHandler`". handler is a string containing the name of the module and the handler function. Optional dir is a string containing the name of the directory to be added to the pythonpath. If no directory is specified, then, if there is already a handler of the same type specified, its directory is inherited, otherwise the directory of the presently executing handler is used. If there is a `PythonPath` directive in effect, then `sys.path` will be set exactly according to it (no directories added, the dir argument is ignored).

  A handler added this way only persists throughout the life of the request. It is possible to register more handlers while inside the handler of the same type. One has to be careful as to not to create an infinite loop this way.

  Dynamic handler registration is a useful technique that allows the code to dynamically decide what will happen next. A typical example might be a `PythonAuthenHandler` that will assign different `PythonHandlers` based on the authorization level, something like:

      if manager:
          req.add_handler("PythonHandler", "menu::admin")
      else:
          req.add_handler("PythonHandler", "menu::basic")

  Note: If you pass this function an invalid handler, an exception will be generated at the time an attempt is made to find the handler.

`allow_methods`( | methods[, reset])

  Adds methods to the `req.allowed_methods` list. This list will be passed in `Allowed:` header if `HTTP_METHOD_NOT_ALLOWED` or `HTTP_NOT_IMPLEMENTED` is returned to the client. Note that Apache doesn't do anything to restrict the methods, this list is only used to construct the header. The actual method-restricting logic has to be provided in the handler code.

  methods is a sequence of strings. If reset is 1, then the list of methods is first cleared.

`document_root`( | )

  Returns DocumentRoot setting.

`get_basic_auth_pw`( | )

  Returns a string containing the password when Basic authentication is used.

`get_config`( | )

  Returns a reference to the table object containing the mod_python configuration in effect for this request except for `Python*Handler` and `PythonOption` (The latter can be obtained via `req.get_options()`. The table has directives as keys, and their values, if any, as values.

`get_remote_host`( | [type, str_is_ip])

  This method is used to determine remote client's DNS name or IP number. The first call to this function may entail a DNS look up, but subsequent calls will use the cached result from the first call.

  The optional type argument can specify the following:

  - `apache.REMOTE_HOST` Look up the DNS name. Return None if Apache directive `HostNameLookups` is `off` or the hostname cannot be determined.

  - `apache.REMOTE_NAME` (Default) Return the DNS name if possible, or the IP (as a string in dotted decimal notation) otherwise.

  - `apache.REMOTE_NOLOOKUP` Don't perform a DNS lookup, return an IP. Note: if a lookup was performed prior to this call, then the cached host name is returned.

  - `apache.REMOTE_DOUBLE_REV` Force a double-reverse lookup. On failure, return None.

  If str_is_ip is `None` or unspecified, then the return value is a string representing the DNS name or IP address.

  If the optional str_is_ip argument is not `None`, then the return value is an `(address, str_is_ip)` tuple, where str_is_ip is non-zero if `address` is an IP address string.

  On failure, `None` is returned.

`get_options`( | )

  Returns a reference to the table object containing the options set by the `PythonOption` directives.

`internal_redirect`( | new_uri)

  Internally redirects the request to the new_uri. new_uri must be a string.

  The httpd server handles internal redirection by creating a new request object and processing all request phases. Within an internal redirect, `req.prev` will contain a reference to a request object from which it was redirected.

`log_error`( | message[, level])

  An interface to the Apache `ap_log_rerror` function. message is a string with the error message, level is one of the following flags constants:

          APLOG_EMERG
          APLOG_ALERT
          APLOG_CRIT
          APLOG_ERR
          APLOG_WARNING
          APLOG_NOTICE
          APLOG_INFO
          APLOG_DEBUG
          APLOG_NOERRNO

  If you need to write to log and do not have a reference to a request object, use the `apache.log_error` function.

`meets_conditions`( | )

  Calls the Apache `ap_meets_conditions()` function which returns a status code. If status is `apache.OK`, generate the content of the response normally. If not, simply return status. Note that `req.headers_out` should be set prior to calling this function. The same goes for `req.status` if the status differs from `apache.OK`.

  Example:

      ...
      r.headers_out['ETag'] = "1130794f-3774-4584-a4ea-0ab19e684268"
      r.headers_out['Last-Modified'] = 'Wed, 23 Feb 2005 00:00:00 GMT'
      r.headers_out['Expires'] = 'Mon, 18 Apr 2005 17:30:00 GMT'

      status = r.meets_conditions()
      if status != apache.OK:
        return status

      ... do expensive generation of the response content ...

`requires`( | )

  Returns a tuple of strings of arguments to `require` directive.

  For example, with the following apache configuration:

      AuthType Basic
      require user joe
      require valid-user

  `requires()` would return `('user joe', 'valid-user')`.

`read`( | [len])

  Reads at most len bytes directly from the client, returning a string with the data read. If the len argument is negative or omitted, reads all data given by the client.

  This function is affected by the `Timeout` Apache configuration directive. The read will be aborted and an `IOError` raised if the `Timeout` is reached while reading client data.

  This function relies on the client providing the `Content-length` header. Absence of the `Content-length` header will be treated as if `Content-length: 0` was supplied.

  Incorrect `Content-length` may cause the function to try to read more data than available, which will make the function block until a `Timeout` is reached.

`readline`( | [len])

  Like `read()` but reads until end of line.

  Note: In accordance with the HTTP specification, most clients will be terminating lines with "`\r\n`" rather than simply "`\n`".

`readlines`( | [sizehint])

  Reads all or up to sizehint bytes of lines using `readline` and returns a list of the lines read.

`register_cleanup`( | callable[, data])

  Registers a cleanup. Argument callable can be any callable object, the optional argument data can be any object (default is `None`). At the very end of the request, just before the actual request record is destroyed by Apache, callable will be called with one argument, data.

  It is OK to pass the request object as data, but keep in mind that when the cleanup is executed, the request processing is already complete, so doing things like writing to the client is completely pointless.

  If errors are encountered during cleanup processing, they should be in error log, but otherwise will not affect request processing in any way, which makes cleanup bugs sometimes hard to spot.

  If the server is shut down before the cleanup had a chance to run, it's possible that it will not be executed.

`sendfile`( | path[, offset, len])

  Sends len bytes of file path directly to the client, starting at offset offset using the server's internal API. offset defaults to 0, and len defaults to -1 (send the entire file).

  Returns the number of bytes sent, or raises an IOError exception on failure.

  This function provides the most efficient way to send a file to the client.

`write`( | string[, flush=1])

  Writes string directly to the client, then flushes the buffer, unless flush is 0.

`flush`( | )

  Flushes the output buffer.

`set_content_length`( | len)

  Sets the value of `req.clength` and the "`Content-Length`" header to len. Note that after the headers have been sent out (which happens just before the first byte of the body is written, i.e. first call to `req.write()`), calling the method is meaningless.