如何在lua中解析json？

Question

Is there any lightweight, preferably pure lua, library for lua to parse json content? Basically I wanna augment my ngnix with a lua module that needs to verfiy some information from a json object I'm getting from Redis .

The object looks like as follow:

{
  "data": {
    "user": {
      "username": "username",
      "type": "TYPE"
    }
  },
  "passport": {
    "user": "uuid"
  },
}

In my lua code, I need to verify if the data.user.username exists. Then I can let the nginx continue with its redirection. Can anybody please show me an example of how can I achieve that?

Answer 1

JSON data in that form is very close to Lua tables. So you can transform the JSON data into Lua code and run it, if you trust the JSON data.

J=[[
{
  "data": {
    "user": {
      "username": "username",
      "type": "TYPE"
    }
  },
  "passport": {
    "user": "uuid"
  },
}
]]
L="return "..J:gsub('("[^"]-"):','[%1]=')
T=loadstring(L)()
print(T.data.user.username)

If have any qualms about the JSON data, you may want to run the string in L in a sandbox.