I am new GAE and I need some help. Is it possible to query for
entities with a property value null using GAE JDO query?
I want something like
"Get me all the Files that don't have a parent"
In regular relational DBs, it can be queried some thing like this:
"select * from File where parentKey is null"
I have a class something like this:
public class File {
@Persistent
@PrimaryKey
private Key id;
@Persistent
String name;
@Persistent
private Key parentKey;
}
When I am querying for Files that have null parentKey, query returns
all Files including those with non-null parentKey value. Is this
possible to do with GAE?
Thanks!
On Dec 22, 1:33 pm, dantuluri <[email protected]> wrote:
> Hi,
>
> I have an entity that has the following structure:
>
> File which has Key as primary key and ParentKey that refers to
> another File which is parent of this File. Example data for this
> structure looks like this:
>
> Key: File(2)
> Name: Inbox
> parentKey: File(1)
>
> It is possible that File may not have a parentKey.
>
> I want to query the DataStore for Files that don't have parent file
> (parentKey == null). But when I am querying with parentKey == null, I
> am still getting all Files including those with parentsKeys. How can
> we do this with JDO query with App Store? I must be missing something
> basic here.
>
> Similarly I would like to get the child folders of a given folder
> (parentKey == File(1)).
>
> Any help would be appreciated!
>
> Thanks
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