I wrote a lua driver(https://github.com/bigplum/lua-resty-mongol) based on openresty(ngx_lua) project. There is an issue: http://forum.nginx.org/read.php?2,226716,226744#msg-226744

1. use lua-resty-mongol inster an embeded array, mongo shell shows ok.
The "undefined" value comes from that lua table index beginning from 1.

local t = {}
table.insert(t,

)
table.insert(t,

)
r, err = col:insert(name="dog",n="10",tab=t, nil, true)

> db.test.find()
{ "_id" : ObjectId("4fbc97e10853d55c767302f8"), "tab" : [ undefined,

,

], "name" : "dog", "n" : "10" }

2. use mongo shell update to push a new value into tab, the last element of tab is overrided.

> db.test.update(

, {$push:{tab:"a5"}})
> db.test.find()
{ "_id" : ObjectId("4fbc97e10853d55c767302f8"), "n" : "10", "name" : "dog", "tab" : [ undefined,

, "a5" ] }

So, is this bug is related with the "undefined" value?