Criteria for ViewFile?

[edulid]

I need to send a parameter to the server in a tilegrid which shows a picture, do something in the server with this parameter, and return the result.
I have a dmi fetch method for this, but I cannot get the parameter that the client set! I have tried a lot of things. (advancedCriteria, criteria, param, property)
There are two fetches for the same datasource : 1) type fetch: the parameter is there (in form of criteria) 2) type viewFile my parameter in form of criteria is missing!!
In the dmi method, which catches the fetch, I the criteria sent is also missing. So I don't know how to get it there.
I only get:
AdvancedCriteria:[and:[and:[{f_schueler_id equals 12360}, {download_fieldname iEquals f_foto}, {download_filename iEquals Serengeti_Elefantenherde1.jpg}], {f_mandant equals 1}]]

Which are fields in the table. My parameter doesn't have a field on the table. But, as I said, is being sent in the fetch.
What to do in this case ?

Using 6.0p power

[Isomorphic]

The viewFile operation sends just the PK of the record that has the image. A TileGrid would not be expected to use the AdvancedCriteria applied to the TileGrid itself when using the viewFile operation, since the PK is supposed to be unique.

It sounds like you may be injecting criteria into the viewFile request by some other (unspecified) means, but if so, it's normal that a field which is not declared in your DataSource may be removed - just declared it there to fix this.

[edulid]

Ok, but how to declare it if it is not a db-field ?
and will it be passed to the viewFile operation if it is found in the fetch operation?

[Isomorphic]

Non-db-fields and db fields use the same declaration format. Maybe you forgot about customSQL="true" and all the other ways of controlling whether such fields generate SQL?

We don't know what "found in the fetch operation" means - as before, you haven't specified how exactly you are sticking this extra data onto the viewFile request.