Option 2 looks nice. Than you Ikai. From: "Ikai Lan (Google)" <ikai.l+gro...@google.com> Reply-To: <google-appengine-java@googlegroups.com> Date: Mon, 1 Nov 2010 15:28:54 -0700 To: <google-appengine-java@googlegroups.com> Subject: Re: [appengine-java] Mapreduce, mutationPool, and child entities
You've got a few options here: 1. Use named keys. You can then use KeyFactory and KeyFactory.Builder to create an entire Key hierarchy. 2. Use KeyRange to generate a range of IDs you can use, and use this as the key of the parent entity http://code.google.com/appengine/docs/java/javadoc/com/google/appengine/api/ datastore/KeyRange.html -- Ikai On Mon, Nov 1, 2010 at 8:11 AM, Cyrille Vincey <crll...@gmail.com> wrote: > I am trying to figure out how to put 2 parent/child entities into the > mutationPool, inside a MapReduce job. > Here is my issue : in my understanding, as the mutationPool is asynchronous , > I cannot expect to get the parent entity key back from the mutationPool.put() > method. > > Or can I ? > According to you, would the following code work or not ? > > [Š] > //Creation of the parent entity > Entity parent = new Entity("ParentClass"); > parent.setProperty("fieldA", valueA); > mutationPool.put(parent); > > //Creation of the child entity > Entity child = new Entity("ChildClass", parent.getKey()); //Q: Can I expect > that the key is returned directly after the mutationPool.put() method ? > child.setProperty("fieldX", valueX); > mutationPool.put(child); > [Š] > > From: "Ikai Lan (Google)" <ikai.l+gro...@google.com> > Reply-To: <google-appengine-java@googlegroups.com> > Date: Mon, 13 Sep 2010 14:15:30 -0700 > To: <google-appengine-java@googlegroups.com> > Subject: Re: [appengine-java] query for null <missing> properties > > You can't. Empty properties are the equivalent of unindexed properties. You'll > need to iterate over all the Entities in your datastore and update them. The > Mapper API is a very good tool for this: > > http://code.google.com/p/appengine-mapreduce/ > > On Mon, Sep 13, 2010 at 12:20 PM, Benjamin <bsaut...@gmail.com> wrote: >> Brain freeze guys - >> >> I added a property to my object and persisted in the datastore. The >> older object have now have a column that when viewed in the control >> panel have a value of <missing>. I need to query those objects so i >> can update them - propname == null , propname == "" - I can't seem >> to find the right syntax for this. >> >> -- >> You received this message because you are subscribed to the Google Groups >> "Google App Engine for Java" group. >> To post to this group, send email to google-appengine-j...@googlegroups.com. >> To unsubscribe from this group, send email to >> google-appengine-java+unsubscr...@googlegroups.com >> <mailto:google-appengine-java%2bunsubscr...@googlegroups.com> . >> For more options, visit this group at >> http://groups.google.com/group/google-appengine-java?hl=en. >> > > > -- > You received this message because you are subscribed to the Google Groups > "Google App Engine for Java" group. > To post to this group, send email to google-appengine-j...@googlegroups.com. > To unsubscribe from this group, send email to > google-appengine-java+unsubscr...@googlegroups.com. > For more options, visit this group at > http://groups.google.com/group/google-appengine-java?hl=en. > > -- > You received this message because you are subscribed to the Google Groups > "Google App Engine for Java" group. > To post to this group, send email to google-appengine-j...@googlegroups.com. > To unsubscribe from this group, send email to > google-appengine-java+unsubscr...@googlegroups.com > <mailto:google-appengine-java%2bunsubscr...@googlegroups.com> . > For more options, visit this group at > http://groups.google.com/group/google-appengine-java?hl=en. -- You received this message because you are subscribed to the Google Groups "Google App Engine for Java" group. To post to this group, send email to google-appengine-j...@googlegroups.com. To unsubscribe from this group, send email to google-appengine-java+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/google-appengine-java?hl=en. -- You received this message because you are subscribed to the Google Groups "Google App Engine for Java" group. To post to this group, send email to google-appengine-j...@googlegroups.com. To unsubscribe from this group, send email to google-appengine-java+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/google-appengine-java?hl=en.
