binder.py 5.65 KB
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# Tweepy
# Copyright 2009 Joshua Roesslein
# See LICENSE

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import httplib
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import urllib
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import time
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from . parsers import parse_error
from . error import TweepError
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try:
    import json #Python >= 2.6
except ImportError:
    try:
        import simplejson as json #Python < 2.6
    except ImportError:
        try:
            from django.utils import simplejson as json #Google App Engine
        except ImportError:
            raise ImportError, "Can't load a json library"

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def bind_api(path, parser, allowed_param=[], method='GET', require_auth=False,
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              timeout=None, host=None):
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    def _call(api, *args, **kargs):
        # If require auth, throw exception if credentials not provided
        if require_auth and not api.auth_handler:
            raise TweepError('Authentication required!')

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        # check for post data
        post_data = kargs.pop('post_data', None)
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        # check for retry request parameters
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        retry_count = kargs.pop('retry_count', api.retry_count)
        retry_delay = kargs.pop('retry_delay', api.retry_delay)
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        # check for headers
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        headers = kargs.pop('headers', {})
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        # build parameter dict
        if allowed_param:
            parameters = {}
            for idx, arg in enumerate(args):
                try:
                    parameters[allowed_param[idx]] = arg
                except IndexError:
                    raise TweepError('Too many parameters supplied!')
            for k, arg in kargs.items():
                if arg is None:
                    continue
                if k in parameters:
                    raise TweepError('Multiple values for parameter %s supplied!' % k)
                if k not in allowed_param:
                    raise TweepError('Invalid parameter %s supplied!' % k)
                parameters[k] = arg
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        else:
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            if len(args) > 0 or len(kargs) > 0:
                raise TweepError('This method takes no parameters!')
            parameters = None

        # Build url with parameters
        if parameters:
            url = '%s?%s' % (api.api_root + path, urllib.urlencode(parameters))
        else:
            url = api.api_root + path

        # Check cache if caching enabled and method is GET
        if api.cache and method == 'GET':
            cache_result = api.cache.get(url, timeout)
            # if cache result found and not expired, return it
            if cache_result:
                # must restore api reference
                if isinstance(cache_result, list):
                    for result in cache_result:
                        result._api = api
                else:
                    cache_result._api = api
                return cache_result

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        # get scheme and host
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        if api.secure:
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            scheme = 'https://'
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        else:
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            scheme = 'http://'
        _host = host or api.host
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        # Continue attempting request until successful
        # or maxium number of retries is reached.
        retries_performed = 0
        while retries_performed < retry_count + 1:
            # Open connection
            # FIXME: add timeout
            if api.secure:
                conn = httplib.HTTPSConnection(_host)
            else:
                conn = httplib.HTTPConnection(_host)

            # Apply authentication
            if api.auth_handler:
                api.auth_handler.apply_auth(
                        scheme + _host + url,
                        method, headers, parameters
                )

            # Build request
            conn.request(method, url, headers=headers, body=post_data)

            # Get response
            resp = conn.getresponse()

            # If request was successful, quit the loop
            if resp.status == 200:
                break

            # Sleep before retrying request again
            time.sleep(retry_delay)
            retries_performed += 1
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        # If an error was returned, throw an exception
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        api.last_response = resp
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        if resp.status != 200:
            try:
                error_msg = parse_error(resp.read())
            except Exception:
                error_msg = "Twitter error response: status code = %s" % resp.status
            raise TweepError(error_msg)

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        # Parse json respone body
        try:
            jobject = json.loads(resp.read())
        except Exception:
            raise TweepError("Failed to parse json response text")

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        # Parse cursor infomation
        if isinstance(jobject, dict):
            next_cursor = jobject.get('next_cursor')
            prev_cursor = jobject.get('previous_cursor')
        else:
            next_cursor = None
            prev_cursor = None

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        # Pass json object into parser
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        try:
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            if next_cursor is not None and prev_cursor is not None:
                out = parser(jobject, api), next_cursor, prev_cursor
            else:
                out = parser(jobject, api)
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        except Exception:
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            raise TweepError("Failed to parse json object")
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        conn.close()

        # validate result
        if api.validate:
            # list of results
            if isinstance(out, list) and len(out) > 0:
                if hasattr(out[0], 'validate'):
                    for result in out:
                        result.validate()
            # single result
            else:
                if hasattr(out, 'validate'):
                    out.validate()

        # store result in cache
        if api.cache and method == 'GET':
            api.cache.store(url, out)

        return out

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    # Set pagination mode
    if 'cursor' in allowed_param:
        _call.pagination_mode = 'cursor'
    elif 'page' in allowed_param:
        _call.pagination_mode = 'page'
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    return _call