how to get query parameter in lua or nginx?

Question

I am trying to implement this- https://gist.github.com/MendelGusmao/2356310 Lua,nginx based URL shortener,The only change i want to implement is when some query string parameter comes with shortened URL i need to take that parameter and insert into the long URL.

e.g. http://google.com?test=2 will be like http://abc.in/abc while hitting on http://abc.in/abc?test=3 I get redirected to - http://google.com?test=3.

For that i need to take query string parameters from $request_URI, can any one help with some code?

Billyebilobate

wiki.nginx.org/HttpLuaModule#ngx.req.get_uri_args – Baliol

Answer 1

You should be able to use ngx.var.arg_name where name is the name of the query parameter you want to access. See Variables with Infinite Names section in this tutorial for details on query parameter handling; you may also check my blog post for Lua nginx/openresty examples.

As an alternative, you can use ngx.req.get_uri_args() to retrieve all query parameters as one table. See this section in the same tutorial for the brief comparison between these methods.

Drumlin

How does the table returned by get_uri_args differ from the table referred to by ngx.var.args? – Kwangchow

ngx.var allows retrieving individual arguments when you know their names (through the use of metafields, these values actually don't exist in the table); get_uri_args() allows retrieving all passed arguments. – Drumlin

Answer 2

You can also use ngx.var.QUERY_STRING to access the query string and unescape and parse it.

Hirschfeld

Answer 3

You can obtain the query parameter with just nginx by using $arg_test, test is the name of the query parameter in this example.

This is documented in http://nginx.org/en/docs/http/ngx_http_core_module.html#var_arg_.

Refuel