Data Conversion

Data conversion divides into two type:

• Request conversion: Depend on request content-type, map raw data into Python object. For example, map JSON string into Python dictionary. In default, Clink convert JSON string and URL Encode to dictionary or list, etc. This handlers must extend from Lv3Handler - Pre-Main Handling.
• Response conversion: Depend on response content-type, convert Python object into string, because send handler accept string as body of response message. In default, Clink convert dictionary, list, etc to JSON string. This handlers must extend from Lv5Handler - Responding Handling

Now, let create data conversion handlers to know “How it work?”. We create two handlers:

• ReqTextHandler converts ‘text/plain’ to list of words.
• ResTextHandler joins list of words to string

And we create main handler to converts list of words to uppercase: TextCtl.process_text

Example

data_conversion.py

# STEP 1: get clink library
from clink import stamp, mapper, App, AppConf, Controller
from clink.iface import ILv3Handler, ILv5Handler
from clink.mime.type import MIME_PLAINTEXT


# STEP 2: get an WSGI server
from wsgiref.simple_server import make_server


# STEP 3: create application configuration and application
conf = AppConf('book-api', 'Hell Corporation', '1st, Hell street')
app = App(conf)


# STEP 4: define components
# ===[BEGIN] ADD DATA CONVERSION HANDLERS ====================================
@stamp()
class ReqTextHandler(ILv3Handler):
    def handle(self, req, res):
        if req.content_type != MIME_PLAINTEXT:
            return
        if req.body is None:
            req.body = []
        else:
            req.body = req.body.decode('utf-8').split(' ')


@stamp()
class ResTextHandler(ILv5Handler):
    def handle(self, req, res):
        if res.content_type != MIME_PLAINTEXT:
            return
        if res.body is None:
            res.body = ''
        else:
            res.body = ' '.join(res.body).encode('utf-8')


@stamp()
@mapper.path('/text')
class TextCtl(Controller):
    @mapper.post('/', MIME_PLAINTEXT)
    def process_text(self, req, res):
        res.body = [w.upper() for w in req.body]
        res.content_type = MIME_PLAINTEXT
# ===[END] ADD DATA CONVERSION HANDLERS ======================================


# STEP 5: add components to application
app.add_handler(ReqTextHandler)
app.add_handler(ResTextHandler)
app.add_ctl(TextCtl)

# STEP 6: load components
app.load()

# STEP 7: serve application on WSGI server
address = 'localhost'
port = 8080
print('Prepare API on http://%s:%i/text' % (address, port))
httpd = make_server(address, port, app)
httpd.serve_forever()

Testing

$ python data_conversion.py &> /dev/null &
[1] 6456

$ curl -X POST -H "Content-Type: text/plain" \
  -d "my name is kevin" localhost:8080/text; echo
MY NAME IS KEVIN

$ kill %1