[ome-devel] Querying Annotations

[josh.moore at gmx.de]

Matthias Dunda writes:
 > Hi,

Hi Matthias,

 > I want to find all annotations to a Dataset. I added
 > CommentAnnotations before and am now willing to read them out
 > again...
 > 
 > First shot:
 > 
 > findAllByQuery("select a from Annotation a " +
 >                         "join DatasetAnnotationLink as dal " +
 >                         "where dal.parent = 1 ", null);
 > 
 > for dataset-ID = 1.
 > 
 > This gives me:
 > 
 > Exception in thread "main" omero.ApiUsageException serverStackTrace
 >     = "ome.conditions.ApiUsageException: Path expected for join!

...

 >     .......
 > 
 > What's the right way?

So, there's a bit of a trick here. If this were any other link like
DatasetImageLinks, the query you were trying to write would be:

... Image as i join i.datasetLinks as dil where dil.parent.id = 1

The important differences being:

 * after "join" you must use dot notation to form a path from the
   objects which are already defined. (In this case, "i")

 * Though the column in the database on Datasetimagelink is called
   "parent" it's not possible to di:

     dil.parent = 1

   but instead use:

     dil.parent.id = 1


*However*, annotation links are different. They are unidirectional,
meaning the annotation doesn't have back-references to all of the many
types which it can be attached, too. Therefore, it's not possible to
use dot notation such as:

   Annotation a join a.datasetLinks ...

but rather you must approache the query from either the Dataset table
or from the DatasetAnnotationLink table.

To make a long story short, you're looking for something along the
lines of:

       select a
         from DatasetAnnotationLink as dal
   join fetch dal.child as a
        where dal.parent.id = 1


 > Thanks
 > Matthias


Very welcome,
~Josh.