jsonresponse.py

import logging

try:
    import json
except ImportError:
    import simplejson as json


log = logging.getLogger(__name__)


class JSONResponse(object):
    """JSONResponse provides a standard method of responding to all JSON ajax
    requests.

    So that we can determine success/failure, related messages, and any html
    data payload we wish to send back to the client

    """
    success = False
    message = ""
    payload = {}

    def __init__(self, success=False, message=None, payload=None):
        """Create JSONResponse

        Check for success, message, payload and make sure payload is a dict
        object
        """

        if success:
            self.success = True

        if message is not None:
            self.message = str(message)
        else:
            self.message = ""

        if payload is not None and isinstance(payload, dict):
            self.payload = payload
        else:
            self.payload = {}

    def jsonify(self):
        """Return a json string of the response """
        return json.dumps(self.dict_response())

    def json_response(self, response):
        """Return a json response with headers set manually

            If we want to combine a single json/html response in one controller
            we can't use the jsonify decorator. We need to do the work that the
            jsonify decorator does in here

        """
        response.headers['Content-Type'] = 'application/json'
        return self.jsonify()

    def dict_response(self):
        """Build a dictionary of the response object """
        return {"success": self.success,
                "message": self.message,
                "payload": self.payload}

from decorator import decorator
def mijson():
    """Action decorator that formats output for JSON

    Given a function that will return content, this decorator will turn
    the result into JSON, with a content-type of 'application/json' and
    output it.

    adds a method to the controller
    self.accepts_json()
    
    It checks if the request comes in accepting json and returns a JSONResponse
    object pulling from:
        self.json.success
        self.json.message
        self.json.payload

    returned html content is placed into json.payload.html

    Otherwise it just returns the html output returned.

    A template variable is set so that the template can conditionaly inherit
    or not
        c.request_ajax = Bool 

    Sample Controller:
        @myjson()
        def pause(self, id):
            result = SomeObj.pause()
            if result:
                self.json.success = True
                self.json.message = 'Paused'
            else:
                self.json.success = False
                self.json.message = 'Failed'

            self.json.payload['job_id'] = id

            return '<h1>Result was: %s</h1>' % message
        
    Response:
        {'success': true, 
            'message': 'Paused', 
            'payload': {'html': '<h1>Result was: Paused</h1>'}}

    """
    def wrapper(func, self, *args, **kwargs):
        request = self._py_object.request
        response = self._py_object.response

        def controller_accepts_json():
            return 'application/json' in request.headers.get('accept', '')


        is_json = False
        self._py_object.c.request_ajax = False
        self.accepts_json = controller_accepts_json

        # go ahead and put this on the controller
        # but we'll only use it if this is a json request
        self.json = JSONResponse()
        self.json.success = False
        self.json.message = ""
        self.json.payload = {}

        if self.accepts_json():
            is_json = True

            # let the template know it's an ajax request
            self._py_object.c.request_ajax = True

        html = func(self, *args, **kwargs)

        if is_json:
            response.headers['Content-Type'] = 'application/json'

            # grab the returned html content and place it in the payload under the
            # key html
            self.json.payload['html'] = html 

            log.debug("Returning JSON wrapped action output")
            return self.json.jsonify()
        else:
            return html
        return func(self, *args, **kwargs)
    return decorator(wrapper)