{"id":543,"date":"2012-02-29T11:36:31","date_gmt":"2012-02-29T10:36:31","guid":{"rendered":"https:\/\/ridgesolutions.ie\/?p=543"},"modified":"2012-02-29T11:54:26","modified_gmt":"2012-02-29T10:54:26","slug":"get_value_for_datastore-example","status":"publish","type":"post","link":"https:\/\/www.ridgesolutions.ie\/index.php\/2012\/02\/29\/get_value_for_datastore-example\/","title":{"rendered":"get_value_for_datastore() example"},"content":{"rendered":"

When using a db.ReferenceProperty<\/a> in google app engine, the function get_value_for_datastore()<\/a> can be used to get the key of a referenced datastore model without causing GAE to automatically fetch the model – this can be very handy if you are trying to optimise the performance of your cloud code.<\/p>\n

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\r\n\r\nfrom google.appengine.ext import db\r\n\r\nclass A(db.Model):\r\n    b = db.ReferenceProperty(B)\r\n\r\nclass B(db.Model):\r\n    name = db.StringProperty()\r\n\r\n<\/code> \r\n<\/pre>\n
In the above code, A contains a reference to B, given a model of type A, b’s key can be retrieved as follows:<\/p>\n
 <\/div>\n
\r\n\r\na = A().get_by_id(1234354)\r\nb_key = A.b.get_value_for_datastore(a)\r\n<\/code> \r\n<\/pre>\n
This will get b’s key without fetching its model!<\/p>\n
 <\/div>\n","protected":false},"excerpt":{"rendered":"
When using a db.ReferenceProperty in google app engine, the function get_value_for_datastore() can be used to get the key of a referenced datastore model without causing GAE to automatically fetch the model – this can be very handy if you are trying to optimise the performance of your cloud code.   from google.appengine.ext import db class […]<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[4],"tags":[115,152,95,97],"class_list":["post-543","post","type-post","status-publish","format-standard","hentry","category-tech-stuff","tag-cloud","tag-datastore","tag-gae","tag-google-app-engine"],"aioseo_notices":[],"aioseo_head":"\n\t\t\n\t\n\t\n\t\n\t\n\t\n\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t