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local mymodule = {}
subprocess = require("subprocess")
local function assert (v, m)
if not v then
m = m or "Assertion failed!"
error(m, 0)
end
return v, m
end
-- ################################################################################
-- PRIVATE DATABASE FUNCTIONS TO BE EXPORTED FOR EACH OBJECT
local export = {}
-- Escape special characters in sql statements
export.escape = function(dbobject, sql)
sql = sql or ""
return dbobject.con:escape(sql)
end
export.databaseconnect = function(dbobject)
if not dbobject.con then
-- create environment object
if dbobject.engine == mymodule.engine.postgresql then
luasql = require("luasql.postgres")
dbobject.env = assert (luasql.postgres())
elseif dbobject.engine == mymodule.engine.sqlite3 then
luasql = require("luasql.sqlite3")
dbobject.env = assert (luasql.sqlite3())
else
error("Unknown database engine "..tostring(dbobject.engine))
end
-- connect to data source
dbobject.con = assert(dbobject.env:connect(dbobject.database, dbobject.user, dbobject.password, dbobject.host, dbobject.port))
return true
end
return false
end
export.databasedisconnect = function(dbobject)
if dbobject.env then
dbobject.env:close()
dbobject.env = nil
end
if dbobject.con then
dbobject.con:close()
dbobject.con = nil
end
end
export.runscript = function(dbobject, script, transaction)
for i,scr in ipairs(script) do
dbobject.runsqlcommand(scr, transaction)
end
end
export.runsqlcommand = function(dbobject, sql, transaction)
if transaction then assert(dbobject.con:execute("SAVEPOINT before_command")) end
local res, err = dbobject.con:execute(sql)
if not res and err then
-- Catch the error to see if it's caused by lack of table
local table
if dbobject.engine == mymodule.engine.postgresql then
table = string.match(err, "relation \"(%S+)\" does not exist")
elseif dbobject.engine == mymodule.engine.sqlite3 then
table = string.match(err, "LuaSQL: no such table: (%S+)")
end
if table and dbobject.table_creation_scripts and dbobject.table_creation_scripts[table] then
if transaction then assert(dbobject.con:execute("ROLLBACK TO before_command")) end
dbobject.runscript(dbobject.table_creation_scripts[table])
dbobject.runsqlcommand(sql)
else
assert(res, err)
end
else
if transaction then
assert(dbobject.con:execute("RELEASE SAVEPOINT before_command"))
end
if type(res) == userdata then
res:close()
end
end
end
export.getselectresponse = function(dbobject, sql, transaction)
local retval = {}
if transaction then assert(dbobject.con:execute("SAVEPOINT before_select")) end
local res, err = pcall(function()
local cur = assert (dbobject.con:execute(sql))
local row = cur:fetch ({}, "a")
while row do
local tmp = {}
for name,val in pairs(row) do
tmp[name] = val
end
retval[#retval + 1] = tmp
row = cur:fetch (row, "a")
end
cur:close()
end)
if not res and err then
-- Catch the error to see if it's caused by lack of table
local table
if dbobject.engine == mymodule.engine.postgresql then
table = string.match(err, "relation \"(%S+)\" does not exist")
elseif dbobject.engine == mymodule.engine.sqlite3 then
table = string.match(err, "LuaSQL: no such table: (%S+)")
end
if table and dbobject.table_creation_scripts and dbobject.table_creation_scripts[table] then
if transaction then assert(con:execute("ROLLBACK TO before_select")) end
dbobject.runscript(dbobject.table_creation_scripts[table])
return dbobject.getselectresponse(sql)
else
assert(res, err)
end
elseif transaction then
assert(dbobject.con:execute("RELEASE SAVEPOINT before_select"))
end
return retval
end
export.listtables = function(dbobject)
local result = {}
if dbobject.engine == mymodule.engine.postgresql then
local tab = dbobject.getselectresponse("SELECT tablename FROM pg_tables WHERE tablename !~* 'pg_*' AND schemaname = 'public' ORDER BY tablename ASC")
for i,t in ipairs(tab) do
result[#result+1] = t.tablename
end
else
-- untested
result = dbobject.con:tables()
end
return result
end
export.listcolumns = function(dbobject, table)
local result = {}
if dbobject.engine == mymodule.engine.postgresql then
local col = dbobject.getselectresponse("SELECT a.attname AS field FROM pg_class c, pg_attribute a, pg_type t WHERE c.relname = '"..dbobject.escape(table).."' AND a.attnum > 0 AND a.attrelid = c.oid AND a.atttypid = t.oid ORDER BY a.attnum")
for i,c in ipairs(col) do
result[#result+1] = c.field
end
end
return result
end
export.listdatabases = function(dbobject)
local result = {}
if dbobject.engine == mymodule.engine.postgresql then
local cmd = {"psql", "-U", "postgres", "-lt"}
if dbobject.host then
cmd[#cmd+1] = "-h"
cmd[#cmd+1] = dbobject.host
end
if dbobject.port then
cmd[#cmd+1] = "-p"
cmd[#cmd+1] = dbobject.port
end
cmd["stderr"]=subprocess.STDOUT
local code, cmdresult = subprocess.call_capture(cmd)
if code ~= 0 then
error(cmdresult, 0)
end
for line in string.gmatch(cmdresult or "", "[^\n]+") do
local table = string.match(line, "%s*([^ |]*)")
if table and table ~= "" then
result[#result+1] = table
end
end
else
error("Invalid database engine", 0)
end
return result
end
-- ################################################################################
-- PUBLIC FUNCTIONS / DEFINITIONS
mymodule.engine = {
["postgresql"] = 1,
["sqlite3"] = 2,
}
mymodule.create = function(engine, database, user, password, host, port)
local dbobject = {engine=engine, database=database, user=user, password=password, host=host, port=port}
for n,f in pairs(export) do
dbobject[n] = function(...) return f(dbobject, unpack(arg)) end
end
return dbobject
end
return mymodule
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