google app engine - Is there a way to sort according to child entities properties in JDO (DataNucleus)? -


We have a parent - child unit models which include the following: 

  @ PersistenceCapable (Detachable = "true") public class field applied Serializable {@PrimaryKey private string name; @Passistent (mapped = "area") @ element (dependent = "true") private list & lt; Category & gt; Categories; } @PersistenceCapable (different = "true") applicable public class category does Serializable {@PrimaryKey @Persistent (valueStrategy = IdGeneratorStrategy.IDENTITY) @Extension (vendorName = "datanucleus", key = "gae.encoded-PK", value = " True ") Private string key; @print private sector area; }

When we recapture all the regions along with their categories, do we name the category?

I saw JDO query can be a setOrdering method, however Sort result unit is being applied to your baby unit and query properties.

We are currently operating like using tree-map, though, is that the JDO / GSQL would be much better to use.

No - including App Engine, questions so you can use a feature of the baby unit A basic unit can not query does not support. ().
If you can query the property of one, then you can think of what that would suit your usage case.

If your categories have unique names, then you can consider a different design where you use class name as the name of the class name followed by the name of the string, after that you have to enter each field unit (an indexed, multi- Properties can be stored as a property), a list of the string name string can be stored in it.
With this kind of design, you will manage the parent's relationship based on the list of the original key names, through the support of JDO for ownership relationships,


Comments

Post a Comment

Popular posts from this blog

Python SQLAlchemy：AttributeError: Neither 'Column' object nor 'Comparator' object has an attribute 'schema' -

I tried to create a new database in my project, but when I run the script, I get this error, I have another project, this type of definition worked before, but now it gets a single error. I am using Python 2.7.8 and the version of SQLAlchemy module is 0.9.8. By the way, using a project flask- SQLAlchemy, it works well, I'm confused. Traceback information is as follows: Traceback (most recent call final): File "D: / Projects / IOM / db_create.py", line 4, & lt; Module & gt; From the models the base file "D: \ Projects \ OO-IM \ models.py", in line 15, in the & lt; Module & gt; Column ( 'followed_id', int (), ForeignKey ( 'user.id')) file "C: \ Python27 \ lib \ site-packages \ SQLAlchemy \ SQL \ schema.py", line 369, __new__ schema = metadata. Schema file "C: \ Python27 \ lib \ site-packages \ SQLAlchemy \ SQL \ elements.py", line 662, AttributeError in __getattr__ key): Neither 'column' object nor ...
Read more

java - How not to audit a join table and related entities using Hibernate Envers? -

I use Eners to be hibernate to audit my institutions. I have an audit entity, Foo , which includes a list & lt; Bars & gt; However, I do not want to audit the bar institutions, in the form of properties, I have written that: @inti @edicated public class Foo {@JoinTable (name = "T_FOO_BAR", joinColumns = @JoinColumn (name = "FOO_ID"), inverseJoinColumns = @JoinColumn (Name = "BAR_ID")) @ManyToMany (Cascade = Persist) @ Indited (targetAuditMode = RelationTargetAuditMode.NOT_AUDITED ) Public listing & lt; Bars & gt; GetBars () {Return bars; }} Now, I want to retrieve an amendment of foo : AuditReader reader = AuditReaderFactory.get (GetEntityManager ()); FU modification = (FU) reader.CreativeTeA () .entensEtrevision (Foo Class, 42) .getSingleResult (); Unfortunately, when I want to retrieve all the data (i.e. when it loads lazy times ), error me ORA-00942: table or view is not present , because Tried to query this: Sel...
Read more

mongodb - CakePHP paginator ignoring order, but only for certain values -

While pagging my user model in kppp, I can sort with some values, but not others. For example, I can order results from created or email , for example, but username or reputation seems to come back order by arbitrary command for example with a list of users: $ this-> paginate = array ('condition' => array ( 'User.is_active' = & gt; true), 'border' => 24, 'order' => array ('User.created' => DESC)); Works as expected, but $ this - & gt; Paged = array ('conditions' = & gt; array (' user.isIactive '= & gt; true),' border '= & gt; 24,' command '= & gt; array (' user repeats' = ' & Gt; DESC ')); No, no. I first thought that this could be a database issue, but when I search the database directly, sorted as expected. Note: I am using Mangodebi with the Mongo DB plugin of Ichikawa for the KPPHP; Pagnetizing users are used to work properl...
Read more