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Date: Tue, 27 Sep 2011 07:34:59 -0500
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Subject: Re: OpenJPA querying on element collections
From: Rick Curtis <curtisr7@gmail.com>
To: users@openjpa.apache.org
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Howard -

Yes, it is possible. I'd recommend reading through the JPA 2.0 spec[1] for =
a
more thorough answer.

Try something like this: SELECT x FROM Item x WHERE KEY(m_properties)=3D 'x=
' <
'h'

Thanks,
Rick

[1] JPA 2.0 -- 4.4.4 Path Expressions -- snippet
..
In the following query, photos is a map from photo label to filename.
SELECT i.name, VALUE(p) FROM Item i JOIN i.photos p WHERE KEY(p) LIKE
=91%egret=92

In the above query the identification variable p designates an abstract
schema type corresponding to the
map value. The results of VALUE(p) and KEY(p) are the map value and the map
key associated with
p, respectively.

The following query is equivalent:
SELECT i.name, p FROM Item i JOIN i.photos p WHERE KEY(p) LIKE =91%egret=92

....


On Mon, Sep 26, 2011 at 1:21 PM, Howard Mak <hmak@antennasoftware.com>wrote=
:

> Hi,
>
> Does anyone know if OpenJPA supports queries on element collections?
>
> Given:
>                @Entity
>                @Table(name=3D"items")
>                public class Item implements Serializable {
>                                @Id
>                                @Column(name=3D"seq_no")
>                                private long m_seqNo;
>
>                                @ElementCollection(fetch=3DFetchType.LAZY)
>                                @CollectionTable(name=3D"properties",
> joinColumns=3D{ @JoinColumn(name=3D"seq_no") })
>                                @MapKeyColumn(name =3D "prop_name")
>                                @Column(name=3D"prop_val")
>                                private Map<String, String> m_properties;
>                }
> ... basically, 1-to-many from "items" to "properties" with schema
>                Table: items
>                Column: seq_no               // primary key
>
>                Table: properties
>                Column: seq_no               // foreign key to "items"
>                Column: prop_name      // m_properties keys
>                Column: prop_val            // m_properties values
>
> Then: running JPA query
>                SELECT x FROM Item x WHERE x.m_properties.get('x') < 'h'
> results in a parse exception for me on OpenJPA v2.0.0.
> Thanks.
>
> - Howard
>
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--=20
*Rick Curtis*

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