DBI.lua

#!/usr/bin/lua

module('DBI', package.seeall)

-- Driver to module mapping

local name_to_module = {

    MySQL = 'dbdmysql',

    PostgreSQL = 'dbdpostgresql',

    SQLite3 = 'dbdsqlite3',

    DB2 = 'dbddb2',

    Oracle = 'dbdoracle',

}

local string = require('string')

-- Returns a list of available drivers

-- based on run time loading

local function available_drivers()

    local available = {}

    for driver, modulefile in pairs(name_to_module) do

	local m, err = pcall(require, modulefile)

	if m then

	    table.insert(available, driver)

	end

    end

    -- no drivers available

    if table.maxn(available) < 1 then

	available = {'(None)'}

    end

    return available

end

 -- High level DB connection function

 -- This should be used rather than DBD.{Driver}.New

function Connect(driver, ...)

    local modulefile = name_to_module[driver]

    if not modulefile then

        local available = table.concat(available_drivers(), ',')

	error(string.format("Driver '%s' not found. Available drivers are: %s", driver, available))

    end

    local m, err = pcall(require, modulefile)

    if not m then

	-- cannot load the module, we cannot continue

        local available = table.concat(available_drivers(), ',')

	error(string.format('Cannot load driver %s. Available drivers are: %s', driver, available))

    end

    local class_str = string.format('DBD.%s.Connection', driver)

    local connection_class = package.loaded[class_str]

    -- Calls DBD.{Driver}.New(...)

    return connection_class.New(...)

end

-- Help function to do prepare and execute in 

-- a single step

function Do(dbh, sql, ...)

    local sth,err = dbh:prepare(sql)

    if not sth then

	return false, err

    end

    local ok, err = sth:execute(...)

    if not ok then

        return false, err

    end

    return sth:affected()

end

-- Lit drivers available on this system

function Drivers()

    return available_drivers() 

end