將Google Appengine 的資料轉成 JSON格式輸出

將以下程式加入程式中
 
from google.appengine.ext import db
from google.appengine.ext.db import BadValueError
import datetime, time
from google.appengine.api import users

SIMPLE_TYPES = (int, long, float, bool, dict, basestring, list)

def to_dict(model):
    output = {}
    if isinstance(model, db.Query):
        output = []
        for v in model:
            output.append(to_dict(v))
        return output
    elif isinstance(model, list):
        output = []
        for v in model:
            output.append(to_dict(v))
        return output
 
    for key, prop in model.properties().iteritems():
        value = getattr(model, key)

        if value is None or isinstance(value, SIMPLE_TYPES):
            output[key] = value
        elif isinstance(value, datetime.date):
            output[key] = value.strftime("%Y/%m/%d %H:%M")
        elif isinstance(value, db.GeoPt):
            output[key] = {'lat': value.lat, 'lon': value.lon}
        elif isinstance(value, db.Model):
            output[key] = to_dict(value)
        elif isinstance(value, users.User):
            output = {}
            methods = ['nickname', 'email', 'auth_domain']
            for method in methods:
                output[method] = getattr(value, method)()
            return output  

        else:
            raise ValueError('cannot encode ' + repr(prop))
    return output

使用範例

import model


rooms= model.Room.all()
self.response.out.write(model.to_dict(rooms))

參考資料

GAE返回JSON数据
How to serialize db.Model objects to json
JSON serialization of Google App Engine models