Using arbitrary ID as key in an array

[edas]

Many web applications use a notation like mymodel[141253][name] where 141253 is the identifier of the described mymodel object.

In the current spec, this will create a JSON array with the key mymodel. In this array, 141252 explicit nullitems will be created, which will be suboptimal both for the size of the JSON message and for the processing time of the recipient.

AFAIK, JSON won't allow to use an array structure with arbitrary keys without explictly creating all keys in the sequence.

One solution would be to always convert mymodel[141253][name] to hash and never to array, generating

{
  "mymodel": {
    "141253": {
      "name": "…"
    }
  }
}

This seems less smart than the current spec, but won't bug on this common use case.

[darobin]

So, beyond the problem of numeric IDs, there's the more general issue of the enabled attacks: just having <input name='foo[999999999999999]'> could use up a fair bit of memory and bandwidth…

I reckon one option is simply to make it so that whenever there is a sparse array, use a hash.

[edas]

I have a fear of automagic like "whenever there is a sparse array".

On application side, this means : I will have a hash… ohh, but not if the ID is 1 because numeric ids won't be sparse so I will have an array in this case : Let's add an "if" in the code that receive the JSON

[darobin]

If your ID is 1 then you get a sparse array :) It's only in the case your array is 0 that you have a potential conflict.

I hear what you're saying though, it does cause worry. The problem is: hashing everything really doesn't help produce JSON of the type that we'd like to get.

[emilv]

See also #15