google-cloud-datastore

问题 I'm using following query to retrieve some entities from google Datastore: var query = datastore.createQuery(namespace,tableName); query.select(['displayName','username']); datastore.getEntitySet(query,function(err,data){ if(err){ res.status(500).end(); } else{ res.send(data); } }); The above code works fine if I select only one property i.e. query.select('username'); But with multiple select its throwing 412 'Precondition Failed' error. my entity looks like the following: Entity properties

问题 I'm using following query to retrieve some entities from google Datastore: var query = datastore.createQuery(namespace,tableName); query.select(['displayName','username']); datastore.getEntitySet(query,function(err,data){ if(err){ res.status(500).end(); } else{ res.send(data); } }); The above code works fine if I select only one property i.e. query.select('username'); But with multiple select its throwing 412 'Precondition Failed' error. my entity looks like the following: Entity properties

问题 I'm using following query to retrieve some entities from google Datastore: var query = datastore.createQuery(namespace,tableName); query.select(['displayName','username']); datastore.getEntitySet(query,function(err,data){ if(err){ res.status(500).end(); } else{ res.send(data); } }); The above code works fine if I select only one property i.e. query.select('username'); But with multiple select its throwing 412 'Precondition Failed' error. my entity looks like the following: Entity properties

问题 I have several records in my database with the same parent. How can I get all of them by parent? 回答1: OK, looks like the following code works: items = ITEM.gql('WHERE ANCESTOR IS :parent', parent=parent_key).fetch(5) 来源： https://stackoverflow.com/questions/7868333/how-to-get-all-records-from-gae-datastore-with-particular-parent

问题 I have several records in my database with the same parent. How can I get all of them by parent? 回答1: OK, looks like the following code works: items = ITEM.gql('WHERE ANCESTOR IS :parent', parent=parent_key).fetch(5) 来源： https://stackoverflow.com/questions/7868333/how-to-get-all-records-from-gae-datastore-with-particular-parent

问题 Consider the classic example of blog data modelling, where we have a Blog entity with many properties, and we want to list the latest blogs in a page. It makes sense to denormalize the BlogPost entity into a BlogPostSummary entity which will be shown in the list view, avoiding fetching and deserializing many unwanted properties. class BlogPost(db.Model): title = db.StringProperty() content = db.TextProperty() created = db.DateProperty() ... class BlogPostSummary(db.Model): title = db

问题 I am developing a web application using Google AppEngine (GAE). I have make some examples using dataStore (free, non-relational) using Google AppEngine Launcher (GAEL). All is correct. However I'd like delete the datastore before to deploy an application. I have read that I have to use the command --clear_datastore I don't know like running the server to delete the data store when I deploy or re-deploy the application. I have chech some ways, for example I have write in the Application

问题 I have 2 models: class Parent (db.Model) : data = db.StringProperty() class Child1 (db.Model) : parent = db.ReferenceProperty(Parent) childData = db.StringProperty() class Child2 (db.Model) : parent = db.ReferenceProperty(Parent) childData2 = db.StringProperty() class Child3 (db.Model) : parent = db.ReferenceProperty(Parent) childData3 = db.StringProperty() .... I want a query which can give me a list of all parents which do not have a child yet. How do i do it? I do not want to maintain an

问题 How do I make a temporary backup of the local datastore in the AppEngine SDK for MacOSX And where are the files located? 回答1: Search for something called "local_db.bin" If you're using a plugin for Eclipse, you'll find this file in WEB-INF/appengine-generated 回答2: local_db.bin is the database file and it is located in your project directory, just make a copy of it. 来源： https://stackoverflow.com/questions/1734826/how-do-i-make-a-temporary-backup-of-the-local-datastore-in-the-appengine-sdk-for

问题 How do I make a temporary backup of the local datastore in the AppEngine SDK for MacOSX And where are the files located? 回答1: Search for something called "local_db.bin" If you're using a plugin for Eclipse, you'll find this file in WEB-INF/appengine-generated 回答2: local_db.bin is the database file and it is located in your project directory, just make a copy of it. 来源： https://stackoverflow.com/questions/1734826/how-do-i-make-a-temporary-backup-of-the-local-datastore-in-the-appengine-sdk-for