Why is the variable modified when nginx Lua processes the request? - nginx

Question

I just started studying Lua.
Every time I request, I want to check the name parameter in the request parameter. However, it is actually found that the self.name has changed occasionally.
For example,
request A with params: request_id = 123 & name = ABC,
request B with params: request_id = 321 & name = EFG,
in the log, I found that there are requests_id = 123, but name = EFG.
Why is that? Is my class incorrectly written?
Here is the sample code：
main.lua:
local checker = require "checker"
local ch = checker:new()
if ch:check_name() then
ngx.header["Content-Type"] = "application/json"
ngx.status = ngx.HTTP_FORBIDDEN
ngx.exit(ngx.HTTP_FORBIDDEN)
end
checker.lua:
local utils = require "utils"
local _M = {}
function _M:new()
local o = {}
setmetatable(o, self)
self.__index = self
self.args = utils.get_req_args() or {}
local name = self.args["name"] or ""
local request_id = self.args["request_id"] or ""
self.name = name
return o
end
function _M:check_name()
ngx.log(ngx.ERR, "request_id: ", self.request_id, " name: ", self.name)
-- do some check ...
end
utils.lua
local json = require "cjson"
local _M = {}
function _M.new(self)
return self
end
function _M.get_req_args()
-- GET
local args = nil
if ngx.var.request_method == "GET" then
args = ngx.req.get_uri_args()
-- POST
elseif ngx.var.request_method == "POST" then
ngx.req.read_body()
local data = ngx.req.get_body_data()
args = json.decode(data)
end
return args
end