Fixtures created badly when primary key is not autonumber

When exporting data where the primary key is not an autonumber the export function will hide the field anyway, merging the keys to the text identifier of the resulting record.

This creates two problems:

• the original value is lost due to size limit of the record identifier
• the database is unable to generate the primary key when data-loading.

A fix is attached that prevents the export function of hiding the said field from the fixture.