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render.py
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# -*- coding: utf-8 -*-)
"""
eve.render
~~~~~~~~~~
Implements proper, automated rendering for Eve responses.
:copyright: (c) 2016 by Nicola Iarocci.
:license: BSD, see LICENSE for more details.
"""
import re
import time
import datetime
import simplejson as json
from werkzeug import utils
from functools import wraps
from eve.methods.common import get_rate_limit
from eve.utils import date_to_str, date_to_rfc1123, config, \
debug_error_message
from flask import make_response, request, Response, current_app as app, abort
try:
from collections import OrderedDict # noqa
except ImportError:
# Python 2.6 needs this back-port
from ordereddict import OrderedDict
# mapping between supported mime types and render functions.
_MIME_TYPES = [
{'mime': ('application/json',), 'renderer': 'render_json', 'tag': 'JSON'},
{'mime': ('application/xml', 'text/xml', 'application/x-xml',),
'renderer': 'render_xml', 'tag': 'XML'}]
def raise_event(f):
""" Raises both general and resource-level events after the decorated
function has been executed. Returns both the flask.request object and the
response payload to the callback.
.. versionchanged:: 0.2
Renamed 'on_<method>' hooks to 'on_post_<method>' for coherence
with new 'on_pre_<method>' hooks.
.. versionchanged:: 0.1.0
Support for PUT.
.. versionchanged:: 0.0.9
To emphasize the fact that they are tied to a method, in `on_<method>`
events, <method> is now uppercase.
.. versionadded:: 0.0.6
"""
@wraps(f)
def decorated(*args, **kwargs):
r = f(*args, **kwargs)
method = request.method
if method in ('GET', 'POST', 'PATCH', 'DELETE', 'PUT'):
event_name = 'on_post_' + method
resource = args[0] if args else None
# general hook
getattr(app, event_name)(resource, request, r)
if resource:
# resource hook
getattr(app, event_name + '_' + resource)(request, r)
return r
return decorated
@raise_event
def send_response(resource, response):
""" Prepares the response for the client.
:param resource: the resource involved.
:param response: either a flask.Response object or a tuple. The former will
simply be forwarded to the client. If the latter a proper
response will be prepared, according to directives within
the tuple.
.. versionchanged:: 0.0.6
Support for HEAD requests.
.. versionchanged:: 0.0.5
Handling the case where response is None. Happens when the request
method is 'OPTIONS', most likely while processing a CORS 'preflight'
request.
.. versionchanged:: 0.0.4
Now a simple dispatcher. Moved the response preparation logic to
``_prepare_response``.
"""
if isinstance(response, Response):
return response
else:
return _prepare_response(resource, *response if response else [None])
def _prepare_response(resource, dct, last_modified=None, etag=None,
status=200, headers=None):
""" Prepares the response object according to the client request and
available renderers, making sure that all accessory directives (caching,
etag, last-modified) are present.
:param resource: the resource involved.
:param dct: the dict that should be sent back as a response.
:param last_modified: Last-Modified header value.
:param etag: ETag header value.
:param status: response status.
.. versionchanged:: 0.7
Add support for regexes in X_DOMAINS values. Closes #660.
ETag value now surrounded by double quotes. Closes #794.
.. versionchanged:: 0.6
JSONP Support.
.. versionchanged:: 0.4
Support for optional extra headers.
Fix #381. 500 instead of 404 if CORS is enabled.
.. versionchanged:: 0.3
Support for X_MAX_AGE.
.. versionchanged:: 0.1.0
Support for optional HATEOAS.
.. versionchanged:: 0.0.9
Support for Python 3.3.
.. versionchanged:: 0.0.7
Support for Rate-Limiting.
.. versionchanged:: 0.0.6
Support for HEAD requests.
.. versionchanged:: 0.0.5
Support for Cross-Origin Resource Sharing (CORS).
.. versionadded:: 0.0.4
"""
if request.method == 'OPTIONS':
resp = app.make_default_options_response()
else:
# obtain the best match between client's request and available mime
# types, along with the corresponding render function.
mime, renderer = _best_mime()
# invoke the render function and obtain the corresponding rendered item
rendered = globals()[renderer](dct)
# JSONP
if config.JSONP_ARGUMENT:
jsonp_arg = config.JSONP_ARGUMENT
if jsonp_arg in request.args and 'json' in mime:
callback = request.args.get(jsonp_arg)
rendered = "%s(%s)" % (callback, rendered)
# build the main wsgi rensponse object
resp = make_response(rendered, status)
resp.mimetype = mime
# extra headers
if headers:
for header, value in headers:
if header != 'Content-Type':
resp.headers.add(header, value)
# cache directives
if request.method in ('GET', 'HEAD'):
if resource:
cache_control = config.DOMAIN[resource]['cache_control']
expires = config.DOMAIN[resource]['cache_expires']
else:
cache_control = config.CACHE_CONTROL
expires = config.CACHE_EXPIRES
if cache_control:
resp.headers.add('Cache-Control', cache_control)
if expires:
resp.expires = time.time() + expires
# etag and last-modified
if etag:
resp.headers.add('ETag', '"' + etag + '"')
if last_modified:
resp.headers.add('Last-Modified', date_to_rfc1123(last_modified))
# CORS
origin = request.headers.get('Origin')
if origin and config.X_DOMAINS:
if isinstance(config.X_DOMAINS, str):
domains = [config.X_DOMAINS]
else:
domains = config.X_DOMAINS
if config.X_HEADERS is None:
headers = []
elif isinstance(config.X_HEADERS, str):
headers = [config.X_HEADERS]
else:
headers = config.X_HEADERS
if config.X_EXPOSE_HEADERS is None:
expose_headers = []
elif isinstance(config.X_EXPOSE_HEADERS, str):
expose_headers = [config.X_EXPOSE_HEADERS]
else:
expose_headers = config.X_EXPOSE_HEADERS
# The only accepted value for Access-Control-Allow-Credentials header
# is "true"
allow_credentials = config.X_ALLOW_CREDENTIALS is True
methods = app.make_default_options_response().headers.get('allow', '')
if '*' in domains:
resp.headers.add('Access-Control-Allow-Origin', origin)
resp.headers.add('Vary', 'Origin')
elif any(re.match(re.escape(domain), origin) for domain in domains):
resp.headers.add('Access-Control-Allow-Origin', origin)
else:
resp.headers.add('Access-Control-Allow-Origin', '')
resp.headers.add('Access-Control-Allow-Headers', ', '.join(headers))
resp.headers.add('Access-Control-Expose-Headers',
', '.join(expose_headers))
resp.headers.add('Access-Control-Allow-Methods', methods)
resp.headers.add('Access-Control-Max-Age', config.X_MAX_AGE)
if allow_credentials:
resp.headers.add('Access-Control-Allow-Credentials', "true")
# Rate-Limiting
limit = get_rate_limit()
if limit and limit.send_x_headers:
resp.headers.add('X-RateLimit-Remaining', str(limit.remaining))
resp.headers.add('X-RateLimit-Limit', str(limit.limit))
resp.headers.add('X-RateLimit-Reset', str(limit.reset))
return resp
def _best_mime():
""" Returns the best match between the requested mime type and the
ones supported by Eve. Along with the mime, also the corresponding
render function is returns.
.. versionchanged:: 0.3
Support for optional renderers via XML and JSON configuration keywords.
"""
supported = []
renders = {}
for mime in _MIME_TYPES:
# only mime types that have not been disabled via configuration
if app.config.get(mime['tag'], True):
for mime_type in mime['mime']:
supported.append(mime_type)
renders[mime_type] = mime['renderer']
if len(supported) == 0:
abort(500, description=debug_error_message(
'Configuration error: no supported mime types')
)
best_match = request.accept_mimetypes.best_match(supported) or \
supported[0]
return best_match, renders[best_match]
def render_json(data):
""" JSON render function
.. versionchanged:: 0.2
Json encoder class is now inferred by the active data layer, allowing
for customized, data-aware JSON encoding.
.. versionchanged:: 0.1.0
Support for optional HATEOAS.
"""
return json.dumps(data, cls=app.data.json_encoder_class,
sort_keys=config.JSON_SORT_KEYS)
def render_xml(data):
""" XML render function.
:param data: the data stream to be rendered as xml.
.. versionchanged:: 0.4
Support for pagination info (_meta).
.. versionchanged:: 0.2
Use the new ITEMS configuration setting.
.. versionchanged:: 0.1.0
Support for optional HATEOAS.
.. versionchanged:: 0.0.3
Support for HAL-like hyperlinks and resource descriptors.
"""
if isinstance(data, list):
data = {config.ITEMS: data}
xml = ''
if data:
xml += xml_root_open(data)
xml += xml_add_links(data)
xml += xml_add_meta(data)
xml += xml_add_items(data)
xml += xml_root_close()
return xml
def xml_root_open(data):
""" Returns the opening tag for the XML root node. If the datastream
includes informations about resource endpoints (href, title), they will
be added as node attributes. The resource endpoint is then removed to allow
for further processing of the datastream.
:param data: the data stream to be rendered as xml.
.. versionchanged:: 0.1.0
Support for optional HATEOAS.
.. versionchanged:: 0.0.6
Links are now properly escaped.
.. versionadded:: 0.0.3
"""
links = data.get(config.LINKS)
href = title = ''
if links and 'self' in links:
self_ = links.pop('self')
href = ' href="%s" ' % utils.escape(self_['href'])
if 'title' in self_:
title = ' title="%s" ' % self_['title']
return '<resource%s%s>' % (href, title)
def xml_add_meta(data):
""" Returns a meta node with page, total, max_results fields.
:param data: the data stream to be rendered as xml.
.. versionchanged:: 0.5
Always return ordered items (#441).
.. versionadded:: 0.4
"""
xml = ''
meta = []
if data.get(config.META):
ordered_meta = OrderedDict(sorted(data[config.META].items()))
for name, value in ordered_meta.items():
meta.append('<%s>%d</%s>' % (name, value, name))
if meta:
xml = '<%s>%s</%s>' % (config.META, ''.join(meta), config.META)
return xml
def xml_add_links(data):
""" Returns as many <link> nodes as there are in the datastream. The links
are then removed from the datastream to allow for further processing.
:param data: the data stream to be rendered as xml.
.. versionchanged:: 0.5
Always return ordered items (#441).
.. versionchanged:: 0.0.6
Links are now properly escaped.
.. versionadded:: 0.0.3
"""
xml = ''
chunk = '<link rel="%s" href="%s" title="%s" />'
links = data.pop(config.LINKS, {})
ordered_links = OrderedDict(sorted(links.items()))
for rel, link in ordered_links.items():
if isinstance(link, list):
xml += ''.join([chunk % (rel, utils.escape(d['href']),
utils.escape(d['title'])) for d in link])
else:
xml += ''.join(chunk % (rel, utils.escape(link['href']),
link['title']))
return xml
def xml_add_items(data):
""" When this function is called the datastream can only contain a `_items`
list, or a dictionary. If a list, each item is a resource which rendered as
XML. If a dictionary, it will be rendered as XML.
:param data: the data stream to be rendered as xml.
.. versionadded:: 0.0.3
"""
try:
xml = ''.join([xml_item(item) for item in data[config.ITEMS]])
except:
xml = xml_dict(data)
return xml
def xml_item(item):
""" Represents a single resource (member of a collection) as XML.
:param data: the data stream to be rendered as xml.
.. versionadded:: 0.0.3
"""
xml = xml_root_open(item)
xml += xml_add_links(item)
xml += xml_dict(item)
xml += xml_root_close()
return xml
def xml_root_close():
""" Returns the closing tag of the XML root node.
.. versionadded:: 0.0.3
"""
return '</resource>'
def xml_dict(data):
""" Renders a dict as XML.
:param data: the data stream to be rendered as xml.
.. versionchanged:: 0.5
Always return ordered items (#441).
.. versionchanged:: 0.2
Leaf values are now properly escaped.
.. versionadded:: 0.0.3
"""
xml = ''
ordered_items = OrderedDict(sorted(data.items()))
for k, v in ordered_items.items():
if isinstance(v, datetime.datetime):
v = date_to_str(v)
elif isinstance(v, (datetime.time, datetime.date)):
v = v.isoformat()
if not isinstance(v, list):
v = [v]
for value in v:
if isinstance(value, dict):
links = xml_add_links(value)
xml += "<%s>" % k
xml += xml_dict(value)
xml += links
xml += "</%s>" % k
else:
xml += "<%s>%s</%s>" % (k, utils.escape(value), k)
return xml