GAEp クックパッド (2018/2/23)

いま流行の Flask で。

• プロジェクトの作成 ~ デプロイ
  Getting Started with Flask on App Engine Standard Environment 
• NDB Key Class : Context, Future, Key, Model, Query, PolyModel, Metadata, Function, Exceptions
  
• Entity Property Reference : BlobKeyProperty, BlobProperty, BooleanProperty, ComputedProperty, DateProperty, DateTimeProperty, FloatProperty, GenericProperty, GeoPtProperty, IntegerProperty, JsonProperty, KeyProperty, LocalStructuredProperty, PickleProperty, StringProperty, StructuredProperty, TextProperty, TimeProperty, UserProperty
• Template Designer Documentation ; Jinja2 Documentation (2.10)

Windows で Flask を使うおまじない。appengine_config.py

# coding: utf-8

# https://issuetracker.google.com/issues/72043776#comment7
import os
import sys
on_appengine = os.environ.get('SERVER_SOFTWARE','').startswith('Development')

if on_appengine and os.name == 'nt':
  sys.platform = "Not Windows"

from google.appengine.ext import vendor

# Add any libraries installed in the "lib" folder.
vendor.add('lib') 

エラー発生時に、コンソール画面へスタックトレースを表示したい

# https://stackoverflow.com/a/46914462
app = Flask(__name__)

import os
production_environment = os.getenv('SERVER_SOFTWARE').startswith('Google App Engine/')

if not production_environment:
  app.debug = True 

空のレスポンス

    # https://stackoverflow.com/a/24295616
    return ('', 201)

Key のパースエラーを包み隠す

  try:
    key = ndb.Key(urlsafe = request.args.get('k'))
  except Exception, e:
    # https://github.com/googlecloudplatform/datastore-ndb-python/issues/143#issuecomment-110869342
    if e.__class__.__name__ == 'ProtocolBufferDecodeError':
      return ('', 404)
    raise

Content-Type を設定

  resp = Response("\n".join(lines))
  resp.headers["content-type"] = 'text/plain'
  return resp

Jinja2 で三項演算子。loop.first ? 'true' : 'false' 。参考

{{ 'true' if loop.first else 'false' }}

?? 演算子も。

{{ value or 'fallback' }}

JSON を返す。参考

from flask import jsonify

return jsonify(root)

自分の URL 参考

from flask import request

request.base_url

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