mysql-proxy result field manipulation - mysql

Question

I have a MYSQL server and MYSQL-PROXY and I am trying to manipualte the results I send to the client as a response to a SELECT query. I have writen this code in lua:
function string.starts(String,Start)
return string.sub(String,1,string.len(Start))==Start
end
function read_query_result(inj)
local fn = 1
local fields = inj.resultset.fields
while fields[fn] do
fn = fn + 1
end
fn = fn - 1
print("FIELD NUMBER: " .. fn)
for row in inj.resultset.rows do
print ("--------------")
for i = 1, fn do
if (string.starts(fields[i].name,"TEST")) then
row[i]="TESTED"
end
print ("DATA: " .. fields[i].name .. " -> " .. row[i])
end
end
return proxy.PROXY_SEND_RESULT
end
I can correctly read the field names and values. I can detect the condition where I want the result modified, but I can not get the data sent to the client.
I see two problems:
I am setting the value in the local row variable, but I have not found the way to set the real resultset (inj.Resultset.row[i] or something similar).
There is something wrong with return proxy.PROXY_SEND_RESULT, because I am seeing that whenever I comment that sentence I see the results, and If I uncomment it I get an error.
I have not found example code as a reference.

Answer 1

Ok. Solved.
Data has to be inserted in a table
PROXY_SEND_RESULT requires proxy.response.type to be set.
This is the correct module:
function read_query_result(inj)
local fn = 1
local fields = inj.resultset.fields
proxy.response.resultset = {fields = {}, rows = {}}
while fields[fn] do
table.insert(proxy.response.resultset.fields, {type = proxy.MYSQL_TYPE_STRING, name = fields[fn].name})
fn = fn + 1
end
fn = fn - 1
for row in inj.resultset.rows do
for i = 1, fn do
if (string.starts(fields[i].name,"TEST")) then
row[i]="TESTED"
end
end
table.insert(proxy.response.resultset.rows, row )
end
proxy.response.type = proxy.MYSQLD_PACKET_OK
return proxy.PROXY_SEND_RESULT
end