How to parse JSON

Solar2D General Questions/Discussion
#1

Hi,

I’m having troubles parsing some JSON stuff. I’m talking to an website API over Oauth and getting some JSON as return

Here’s some of my main.lua code:

local request\_response = oAuth.makeRequest("http://api.mysite.com/users/list.json", params, consumer\_key, access\_token, consumer\_secret, access\_token\_secret, "GET" )   
  
local myCode\_encoded = json.encode(request\_response)  
local myCode\_decoded = json.decode(myCode\_encoded)  
  
print (myCode\_decoded)

This outputs the following JSON:

[{"id":"1","email":"some@email.com","username":"someuser","firstname":"James","lastname":"Wilson","country":"UK","city":"London","address":"Oxfordstreet 55","latlng":"50.12345,3.123456","work":"Developer","sex":"male","biography":"Apple fan, ...","gardenSize":"950.00"},{"id":"2","email":"some@othermail.com","username":"azerty","firstname":"Rick","lastname":"Astley","country":"UK","city":"London","address":"Oxfordstreet","latlng":"","work":"","sex":"male","biography":""}]

How do i select the separate nodes for each record ?

This doesn’t work:

 print(myCode\_encoded.id[1])

It gives me an error:

Runtime error: main.lua:37: attempt to index field ‘id’ (a nil value)
Who can help me on my way ?

Thx

Lieven [import]uid: 13439 topic_id: 13134 reply_id: 313134[/import]

#2

Try something like this:

print(myCode_decoded[“id”])
print(myCode_decoded[“email”])

Jay

[import]uid: 9440 topic_id: 13134 reply_id: 48221[/import]

#3

Hi Jay,

print(myCode\_decoded["id"])

Nope … that just gives me a “nil” !
Any other idea’s ?

Lieven [import]uid: 13439 topic_id: 13134 reply_id: 48274[/import]

#4

This tutorial, just posted, might be useful for you:

http://blog.anscamobile.com/2011/08/tutorial-exploring-json-usage-in-corona/ [import]uid: 52430 topic_id: 13134 reply_id: 48653[/import]

#5

Hi Jonathan,

I noticed that my JSON output starts and ends with “[]”.
Does this mean it’s not decoded successfully ?

Any idea’s ?

I tried some things from your blogpost, but without success :frowning:
Lieven [import]uid: 13439 topic_id: 13134 reply_id: 48659[/import]

#6

ok, I think i understand why I’m getting a nil… my JSON that i’m getting from the server is interpreted as a string, not as a JSON object.

How can i convert that JSON string to real JSON (in a table) ?
Lieven [import]uid: 13439 topic_id: 13134 reply_id: 48673[/import]

#7

print(myCode_encoded[1].id) perhaps?
Looks like a array containing objects being returned from the server. [import]uid: 14451 topic_id: 13134 reply_id: 48785[/import]

#8

I found a solution for my problem.

I was first encoding the json that was returned and then decoding it.
If I only decode it (without encoding) then it works fine.

Thanks all for the help.

Lieven [import]uid: 13439 topic_id: 13134 reply_id: 48789[/import]