How to get at JSON in grails 2.0

Question

I am sending myself JSON like so with jQuery:

$.ajax
({
  type: "POST",
  url: 'http://localhost:8080/myproject/myController/myAction',
  dataType: 'json',
  async: false,
  //json object to sent to the authentication url
  data: {"stuff":"yes",
         "listThing":[1,2,3],
         "listObjects":[{"one":"thing"},{"two":"thing2"}]},
  success: function () {
    alert("Thanks!"); 
  }
})

I send this to a controller and do

println params

And I know I'm already in trouble...

[stuff:yes, listObjects[1][two]:thing2, listObjects[0][one]:thing, listThing[]:[1, 2, 3], action:myAction, controller:myController]

I cannot figure out how to get at most of these values...

I can get "yes" with params.stuff, but I cant do params.listThing.each{} or params.listObjects.each{}

What am I doing wrong?

UPDATE:

I make the controller do this to try the two suggestions so far:

println params
println params.stuff
println params.list('listObjects')
println params.listThing
def thisWontWork = JSON.parse(params.listThing)
render("omg l2json")

look how weird the parameters look at the end of the null pointer exception when I try the answers:

[stuff:yes, listObjects[1][two]:thing2, listObjects[0][one]:thing, listThing[]:[1, 2, 3], action:l2json, controller:rateAPI]
yes
[]
null
| Error 2012-03-25 22:16:13,950 ["http-bio-8080"-exec-7] ERROR   errors.GrailsExceptionResolver  - NullPointerException occurred when processing request: [POST] /myproject/myController/myAction - parameters:
stuff: yes
listObjects[1][two]: thing2
listObjects[0][one]: thing
listThing[]: 1
listThing[]: 2
listThing[]: 3

UPDATE 2 I am learning things, but this can't be right:

println params['listThing[]']
println params['listObjects[0][one]']

prints

[1, 2, 3]
thing

It seems like this is some part of grails new JSON marshaling. This is somewhat inconvenient for my purposes of hacking around with the values. How would I get all these individual params back into a big groovy object of nested maps and lists?

Maybe I am not doing what I want with jQuery?

UPDATE jQuery was the issue: Grails: where does request.JSON come from, and how do I put things there with jQuery's .ajax() or .post()?

Did you try with `params.list('listObjects')`? That's the proper way of accessing list parameters. — Esteban, Mar 26 '12 at 03:32

score 1 · Accepted Answer · answered Mar 26 '12 at 05:29

1

Sorry if 2.0 has changed this behavior, but in 1.3.7 I used the following to parse JSON data:

request.JSON.each {params  ->
...

give this a try.

answered Mar 26 '12 at 05:29

dbrin

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Not sure if I'm doing it right: I added that to my controller, and I'm getting the error: `Missing value. at character 0 of .` – Mikey Mar 26 '12 at 06:01
did you complete the closure? – dbrin Mar 26 '12 at 06:05
put the debug at at the top of the action: log.debug("Incoming: "+request.JSON) – dbrin Mar 26 '12 at 06:06
That line crashes with the same error, I'm pretty sure this is grails 2.0 stuff, see my update2. – Mikey Mar 26 '12 at 06:18
This is what I wanted, but jQuery is messing up the call somehow. – Mikey Mar 28 '12 at 19:13

score 1 · Answer 2 · answered Mar 28 '12 at 15:03

1

If you're sending JSON back to the controller, the best thing for you to do is just have Grails marshel it for you back into your objects.

Note the parseRequest attribute below

"/product/$id"(controller: "product", parseRequest: true) {
    action = [GET: "show", PUT: "update", DELETE: "delete", POST: "save"
}

Then in your controller it is simple as:

def save = {
    def productInstance = new Product(params.product)
}

No need to parse your params or anything. This is of course assuming you can structure your JSON to a Domain.

answered Mar 28 '12 at 15:03

Gregg

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This works great, but in this case I actually want to mess around with a big mess of JSON data that isn't one of my domain objects. Gonna +1, but my problem is actually in the jQuery. – Mikey Mar 28 '12 at 19:14
Make sure you are whitelisting which fields in Product you want to set with params.product. Otherwise this might be a security flaw. – dgtized Apr 17 '12 at 03:10

score 0 · Answer 3 · answered Mar 25 '12 at 22:00

0

params always come in as Strings, so you need to do something to convert the input to an actual list. You can do this with grails.converters.JSON.parse(params.listThing).

answered Mar 25 '12 at 22:00

doelleri

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`println params.listThing` prints `null` and giving it to the JSON parser makes a null pointer exception. – Mikey Mar 26 '12 at 05:17

How to get at JSON in grails 2.0

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