Ladonize

Access WSGI environ from service methods

If you define your service method so it accepts keyword args (**kwargs) you can recieve the environ dict directly from the WSGI framework that is serving your application. Also some Ladon specific information is passed via the keyword arguments:

Ladon Environ Key	Description
LADON_METHOD_TC	The request specific TypeConverter (dependent on client encodings)
LADON_ACCEPT_LANGUAGES	List of languages accepted by the caller, most important first
attachments	Direct access to all request attachments (list)
attachments_by_id	Direct access to all request attachments by id (dict)

Example:

from ladon.ladonizer import ladonize

class ClientProbeService(object):

                @ladonize(rtype=str)
                def extract_remote_addr(self,**exports):
                                """
                                Fetch the client's remote address
                                @rtype: The address
                                """
                                return exports['REMOTE_ADDR']

In the above example the WSGI environ variable ‘REMOTE_ADDR’ is used to extract the clients IP-address.

Writing Python 2/3 compatible services

Let’s study another example:

from ladon.ladonizer import ladonize
from firm.customerstore import getCustomerName

class CustomerService(object):

                @ladonize(int,rtype=unicode)
                def getCustomerName(self,customer_no):
                                """
                                Lookup a customer number and resolve the customer name.
                                @rtype: The customer name
                                """
                                return getCustomerName(customer_no)

The example above is clearly not Python 3 compatible as it uses the unicode type directly. In Python 3 the type you want to use if you need unicode support is str. Ladon has a simple solution to this problem if you wish to make use of it. Instead of stating the actual Python type names (bytes/str/unicode) use the type defines PORTABLE_BYTES and PORTABLE_STRING from ladon.compat. This will make the Ladon framework resolv string/bytes types according to the Python version.

So if you use the PORTABLE_STRING definition in your service implementation and start your service with Python 2 it will resolve to unicode, if you start it with Python 3 it will resolve to str

Example made portable:

from ladon.ladonizer import ladonize
from firm.customerstore import getCustomerName
from ladon.compat import PORTABLE_STRING

class CustomerService(object):

                @ladonize(int,rtype=PORTABLE_STRING)
                def getCustomerName(self,customer_no):
                                """
                                Lookup a customer number and resolve the customer name.
                                @rtype: The customer name
                                """
                                return getCustomerName(customer_no)

I the re-written example unicode has been replaced with PORTABLE_STRING. So given that the pseudo module firm.customerstore is also version independent everything should work.