FreeSWITCH Dbh 'fetch' convenience functions for Lua

freeswitch.Dbh is the method I’ve chosen for connecting to a database via a Lua script in FreeSWITCH.

The interface is simple to use, and provides all the basics needed to communicate with a database via a configured ODBC driver.

One thing I found lacking, however, were ‘fetch’ type helper functions, that:

Returned a multi-row result in a table of tables
Returned a single-row result in a table
Returned a single-row, single-column result directly.

Below are the helper functions I came up with. You might also be able to extend the dbh object directly with methods – I just chose to pass the dbh object into a standalone function call.

--[[ Wrapper for freeswitch.Dbh to fetch results into an indexed table of assocative tables. ]] function db_fetch(dbh, sql) local rows = {} dbh:query(sql, function(data) local row = {} for col, val in pairs(data) do row[col] = val end table.insert(rows, row) end) return rows end --[[ Convenience function to return only the first row of a result. ]] function db_fetch_one(dbh, sql) return db_fetch(dbh, sql)[1] end --[[ Convenience function to return a single result. ]] function db_result(dbh, sql) local row = db_fetch_one(dbh, sql) if row then local _, val = next(row) return val end end