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106 lines
3.0 KiB
Python
106 lines
3.0 KiB
Python
"""Blockly Demo: Storage
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Copyright 2012 Google LLC
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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"""
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"""Store and retrieve XML with App Engine.
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"""
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__author__ = "q.neutron@gmail.com (Quynh Neutron)"
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import cgi
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import hashlib
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from random import randint
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from google.cloud import ndb
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class Xml(ndb.Model):
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# A row in the database.
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xml_hash = ndb.IntegerProperty()
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xml_content = ndb.TextProperty()
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last_accessed = ndb.DateTimeProperty(auto_now=True)
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def keyGen():
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# Generate a random string of length KEY_LEN.
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KEY_LEN = 6
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CHARS = "abcdefghijkmnopqrstuvwxyz23456789" # Exclude l, 0, 1.
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max_index = len(CHARS) - 1
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return "".join([CHARS[randint(0, max_index)] for x in range(KEY_LEN)])
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def xmlToKey(xml_content):
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# Store XML and return a generated key.
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xml_hash = int(hashlib.sha1(xml_content.encode("utf-8")).hexdigest(), 16)
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xml_hash = int(xml_hash % (2 ** 64) - (2 ** 63))
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client = ndb.Client()
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with client.context():
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lookup_query = Xml.query(Xml.xml_hash == xml_hash)
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lookup_result = lookup_query.get()
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if lookup_result:
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xml_key = lookup_result.key.string_id()
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else:
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trials = 0
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result = True
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while result:
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trials += 1
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if trials == 100:
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raise Exception("Sorry, the generator failed to get a key for you.")
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xml_key = keyGen()
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result = Xml.get_by_id(xml_key)
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row = Xml(id = xml_key, xml_hash = xml_hash, xml_content = xml_content)
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row.put()
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return xml_key
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def keyToXml(key_provided):
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# Retrieve stored XML based on the provided key.
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# Normalize the string.
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key_provided = key_provided.lower().strip()
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# Check datastore for a match.
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client = ndb.Client()
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with client.context():
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result = Xml.get_by_id(key_provided)
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if not result:
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xml = ""
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else:
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# Put it back into the datastore immediately, which updates the last
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# accessed time.
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with client.context():
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result.put()
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xml = result.xml_content
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# Add a poison line to prevent raw content from being served.
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xml = "{[(< UNTRUSTED CONTENT >)]}\n" + xml
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return xml
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def app(environ, start_response):
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headers = [
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("Content-Type", "text/plain")
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]
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if environ["REQUEST_METHOD"] != "POST":
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start_response("405 Method Not Allowed", headers)
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return ["Storage only accepts POST".encode('utf-8')]
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forms = cgi.FieldStorage(fp=environ["wsgi.input"], environ=environ)
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if "xml" in forms:
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out = xmlToKey(forms["xml"].value)
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elif "key" in forms:
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out = keyToXml(forms["key"].value)
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else:
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out = ""
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start_response("200 OK", headers)
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return [out.encode("utf-8")]
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