topic Re: Why? Variables of type ByteArray cannot be used to query in Alfresco Archive

Why? Variables of type ByteArray cannot be used to query

mgriffith — Mon, 08 Aug 2011 21:57:15 GMT

Hello all, I have a POJO that I am using to create some meta-data for a user task, so that I may be able to link back to it from a MVC controller like Spring or Struts. I was previously just doing this with a UUID, storing that in the task as a variable and using the task service to look up my task

Re: Why? Variables of type ByteArray cannot be used to query

ronald_van_kuij — Mon, 08 Aug 2011 23:05:21 GMT

Because it simply is meant for things that do not need to be queried… It never will be either. The uuid approach you used was better

Re: Why? Variables of type ByteArray cannot be used to query

mgriffith — Mon, 08 Aug 2011 23:23:02 GMT

How can I add additional fields or meta data to the task?

I don't see why the Pojo is allowed to be set if it can't be queried.

– MG

Re: Why? Variables of type ByteArray cannot be used to query

ronald_van_kuij — Tue, 09 Aug 2011 00:52:02 GMT

You can put jpeg files in it, serialized pojo's etc.. All stuff that yo do not query, see it as a normal db blob. How often do you query IN blobs? You can add basic metadata in variables, like you do now. But maybe you want it in your domain model and have a cross reference.

Or enhance the bpmnparser to bemable to add your own extensions on te bpmn level. That is how it should be

Re: Why? Variables of type ByteArray cannot be used to query

mgriffith — Tue, 09 Aug 2011 01:52:00 GMT

By serialized pojo you mean a persistent domain model, such as a Jpa entity, is that correct?

Re: Why? Variables of type ByteArray cannot be used to query

frederikherema1 — Tue, 09 Aug 2011 07:05:57 GMT

Not all DB's support using a BLOB as a condition in the where-clause (which kinda makes sense, potentially comparing loads of data).

A solution whould be to store the ID of your pojo as a seperate variable or create your own variable-type (search the forum on how to do this) which stores the ID and the ref to the byteArray in one variable-record.

Re: Why? Variables of type ByteArray cannot be used to query

ronald_van_kuij — Tue, 09 Aug 2011 09:05:31 GMT

By serialized pojo you mean a persistent domain model, such as a Jpa entity, is that correct?

No, just a serialized pojo. Activiti and how it 'stores' JPA entities is a different thing and only slightly related (the normal entitymanager is used to store the jpa entity and only a reference is stored in activiti)

Re: Why? Variables of type ByteArray cannot be used to query

mgriffith — Tue, 09 Aug 2011 13:19:17 GMT

Not all DB's support using a BLOB as a condition in the where-clause (which kinda makes sense, potentially comparing loads of data).

A solution whould be to store the ID of your pojo as a seperate variable or create your own variable-type (search the forum on how to do this) which stores the ID and the ref to the byteArray in one variable-record.

Did you see my TaskMetaData class above? It is a serialized pojo. I guess I'm not sure what you mean, and such was the original reason for this post. If I understand you correctly, I should be able to store a serialized pojo and query it, which is what I am trying to do – which subsequently throws the exception. Can you provide a code example?

Re: Why? Variables of type ByteArray cannot be used to query

ronald_van_kuij — Tue, 09 Aug 2011 21:31:19 GMT

You understood wrong, I is not possible to query bytearray variables, just like it is almost always senseless to query real blob data.

Re: Why? Variables of type ByteArray cannot be used to query

mgriffith — Tue, 09 Aug 2011 21:42:48 GMT

You understood wrong, I is not possible to query bytearray variables, just like it is almost always senseless to query real blob data.

I'm not disputing that I'm wrong. Clearly I am because I'm getting the exception. It's not clear to me how my pojo is considered a byte array variable…

Re: Why? Variables of type ByteArray cannot be used to query

ronald_van_kuij — Tue, 09 Aug 2011 22:37:00 GMT

What should it otherwise be? A java.lang.String, java.lang.Integer? It can't since it isn't. It's youR class. So if you save it as a variable, a check is done if it can be serialized. And guess what the safest 'format' is for storing serialized objects… Yes, a byte array… That is just how it works as is described in te docs