Finding and Storing JSON Nested Arrays When Names Unknown

Question

Sorry if this has been answered elsewhere here, I have not found it if it has been. I have valid JSON:

{
    "main": [
        {
            "Example1": [
                {
                    "Example1_Var02": "5",
                    "Example1_Var09": "443",
                    "Example1_Var27": "23",
                    "Example1_Var01": "31"
                }
            ],
            "Example2": [
                {
                    "Example2_Var99": "2",
                    "Example2_Var84": "344",
                    "Example2_Var46": "56",
                    "Example2_Var03": "78"
                }
            ]
        }
    ]
}

whose names are unknown to me and/or will change regularly, except for the super key of "main." Assuming a successful $.ajax() call that returns "data," e.g. success: function(data) { , I would like to break out each nested array into localstorage without needing to know their key names, as I may never know them. But as it is, I cannot get something where I know those sub-array names to work. This:

for(var key in data){
   localStorage.setItem(key, JSON.stringify(data[key]));
}

will create a single localstorage instance of "main". But this (and other variations):

for(var key in data){
   localStorage.setItem(key.Example1[0], JSON.stringify(data[key.Example1]));
}

returns an error "Uncaught TypeError: Cannot read property '0' of undefined". And since I cannot accomplish this with a known subarray key name, doing it at an abstract, anonymous level is more challenging still. How can I simply output whatever nested arrays happen to be contained in "main" to separate local storage without necessarily knowing their names in the JSON? Thanks for your help.

Where in the world did the "Hole1Info" come from? I mean, that appears nowhere in the JSON. — Pointy, Apr 10 '14 at 15:36
also if you know there's a key "main", why not just do `for (var key in data.main)` ?? — Pointy, Apr 10 '14 at 15:36
possible duplicate of [Access / process (nested) objects, arrays or JSON](http://stackoverflow.com/questions/11922383/access-process-nested-objects-arrays-or-json) — Felix Kling, Apr 10 '14 at 15:38
Right you are, @Pointy, my apologies -- I have edited the answer to remove that instance. For you and Felix Kling, I may know there is a super array named "main," but no knowledge of the arrays it contains. I'm trying to get a completely anonymous way of finding out what those arrays contained in "main" are and outputting whatever those arrays are to localstorage, a different implementation than Felix' undeniably awesome canonical answer about nested data structures. — jimiayler, Apr 10 '14 at 16:36

score 2 · Accepted Answer · answered Apr 10 '14 at 16:04

As @Pointy pointed out, if you can always expect main to be there and the structure of the object is predictable (even if the names and data aren't) you can use a for...in statement to iterate over the object:

for(var outer in x.main){ 
    for(var inner_key in x.main[outer]){ 
        localStorage.setItem(inner_key, JSON.stringify(x.main[outer][inner_key]));

    }
}

console.log(localStorage.getItem('Example1'));
// "[{"Example1_Var02":"5","Example1_Var09":"443","Example1_Var27":"23","Example1_Var01":"31"}]"

Absolutely what I was looking for -- my knowledge of these syntaxes when working with objects is woefully limited, so truly appreciate whatever help I can get. Thanks, Rob! — jimiayler, Apr 10 '14 at 16:51

Finding and Storing JSON Nested Arrays When Names Unknown

1 Answers1