Estron export support

The OFX Specification (available via http://www.ofx.net/OFXExamplesPage/OFXExamples.aspx) includes details of handling invoices via OFX. It would be natural for Estron to use this support in scripts that create invoice data from estron data sources.

This indicates the need for estron to be able to not only run queries and present results in a GUI but also to export that data in machine-interpretable formats so that metadata calculated from one data source is made available for further calculations.

Currently, there is only theoretical support for export - there are a variety of possibilities (or a permutation of these):

• support in libestron for SaveAs buttons to include all existing backend modules
• explicit support in estron files to denote the export format
• calculated data put into intermediate data sources for processing by a second estron file
• new modules for common formats like CSV, SQL, maybe IIF and OFX. The problem is that estron might not be able to use these as input formats, at least not initially.

Of these options, explicit support is probably the simplest to provide as the estron file concerned would need to define the export format from the internal data types. That kind of mapping could be very difficult to do on a generic basis so there will need to be some kind of "knowledge" embedded into the maps and therefore a relationship between the estron files that use a particular backend for export and the kind of functionality in the estron file itself.

Intermediate sources may be unnecessarily complicated - if there is a need for an intermediate format, might as well try to make that format as generic as possible.

One solution for CSV export (and possibly XML) is for an estron handler to accept a series of tags that represent the columns (or tags) in the export format, respectively. The XML handler would need some kind of secondary mapping to describe the intended tag names as well as the data to put into the tags via the data itself.