fix copy() bug when params has table value

[MiaoZhou]

When handle with:

• get request like /test?foo=bar&bar=baz&bar=blah
• post request with body foo=bar&bar=baz&bar=blah

params(first passing t to copy()) should be {foo = "bar", bar = {"baz", "blah"}}.

The excute will throw an attempt to index local 'visited' (a nil value) error.

[mikz]

@MiaoZhou thanks for raising this point!

This is hard topic, as every library/framework tend to do things differently. I believe if two inputs with the same name are sent, the last one should win because thats how Ruby Rack does it. To send arrays, there is name[] convention, that treats all the params as an array.

Would it make sense to have it configurable? Just extract the merge strategy to a function and expose it as rack.merge_params.

[MiaoZhou]

@mikz thanks for your reply.

I use r:match() in my main.lua file. The code like this:

r:match({
  get = {
    ['/foo']     = function(params) funcA(params) end,
    ['/foo/bar'] = function(params) funcB(params) end
  },
  post = {
    ['/foo']     = function(params) funcC(params) end,
    ['/foo/bar'] = function(params) funcD(params) end
})

The main.lua file only dispatch request to different lua modules that handle with specific logical things.

To make the code clean and neat, i passed all get or post args as r:excute()'s third param depending on what ngx.req.get_method() returned.

That's what i got an error. It's my implementation cause this. There's no need to merge this commit.

Thanks again for making me think more.