How to take values on complex JSON tables?

Solar2D General Questions/Discussion
#1

Greetings,

I am dealing with social issues. I know the value of the decode JSON table, but now I have a problem.

local UserDataJson = json.encode( UserData, { indent = true } )

{

  “scriptData”: {

    “friendsList”: {

      “5ce69a4ecf0xxxxxx237d5d4”: {

        “displayName”: “Mark”

      },

      “5cexxxxxxdddc5237d664”: {

        “displayName”: “Peter”

      }

    }

  }

}

In the middle is the User ID, I used xxx to hide.

I used UserDataJson.friendsList to get a table reply.

I tried to use UserDataJson.friendsList[1] or UserDataJson.friendsList.displayName to get nil.

Is there a way to get the middle UID and displayName individually?

Thank you.

#2

Have you tried to iterate over friendsList using in pairs? 

https://docs.coronalabs.com/api/library/global/pairs.html

#3

Dear Nick,

I tried to use this method.

But it keeps appearing.

bad argument #1 to ‘pairs’ (table expected, got string)

#4

Your JSON doesn’t make much sense to me.  Try

{ {"id":"5ce69a4ecf0xxxxxx237d5d4", "name": "Mark"}, {"id":"5cexxxxxxdddc5237d664": "name": "Peter"}, }
#5

Sounds like you’re trying to iterate over the JSON, not the original Lua tables. You need to decode the JSON into a Lua table before you can dig into it.

#6

Yes, you encode to save and decode to use.  Still I advise using a more normalised data structure.

#7

I have decode it beforehand.

This table is from GameSparks CloudCode to Corona.

After decode, the result of print↓

{

 “friendsList”:{

  “5ce69a4ecf0xxxxxx237d5d4”:{

      “displayName”:“Mark”

     },

    “5cexxxxxxdddc5237d664”:{

        “displayName”:“Peter”

     }

    }

  }

But the system does not seem to recognize the value of friendsList.

#8

That’s not decoded JSON, that’s a JSON string. Can you show the code where you are decoding?

#9

getLocationRequest:send(function(response)
if response:hasErrors() then
–If errors then print errors
else
local FriendData = response:getScriptData()
local FriendJson = json.encode( FriendData, { indent = true } )
native.showAlert(“FriendData”, json.encode( FriendData, { indent = true } ), {“Ok”})
end
end)

#10

You are using EN code not DE code.

#11

Oh, indeed, because of the use of decode will produce nil.

#12

Well, if the JSON string won’t decode that just means your JSON is malformed. You can’t encode a string and expect to be able to access data within it - it’s not a data structure that Corona understands.

What does response:getScriptData() do?

#13

The result of response is the one posted at the top, and the same output result in Gamespark’s Test tool.

I just used decode but the result is the same as nil. :frowning:

I think I have to go to the hospital to undergo the suture after surgery.

Thank you all.

#14

What happens if you try to decode the raw response?

#15

I found the problem. !!!

Just in the hospital, I kept thinking about the method you provided.

   local FriendData = response:getScriptData()

   local FriendJson = json.encode( FriendData , { indent = true }

   local decoded, pos, msg = json.decode( FriendJson )

    if not decoded then

           print( "Decode failed at “…tostring(pos)…”: "…tostring(msg) )

    else

           print( decoded.friendsList )  – Get a table value

           for k,v in pairs( decoded.friendsList ) do

                 print( "UID: “…k…” | " )

                 for a,b in pairs( v ) do

                     print( "displayName: “…a…” | "…b )

                 end

           end

  end

If I only use in pairs once, the latter will get error.

Dear Nick, thank you for your guidance. :smiley:

#16

Have you tried to iterate over friendsList using in pairs? 

https://docs.coronalabs.com/api/library/global/pairs.html

#17

Dear Nick,

I tried to use this method.

But it keeps appearing.

bad argument #1 to ‘pairs’ (table expected, got string)

#18

Your JSON doesn’t make much sense to me.  Try

{ {"id":"5ce69a4ecf0xxxxxx237d5d4", "name": "Mark"}, {"id":"5cexxxxxxdddc5237d664": "name": "Peter"}, }
#19

Sounds like you’re trying to iterate over the JSON, not the original Lua tables. You need to decode the JSON into a Lua table before you can dig into it.

#20

Yes, you encode to save and decode to use.  Still I advise using a more normalised data structure.