json和多维数组

Question

I have a multidimensional array like this

Array
(
    [1] => Array
        (
            [product_id] => 1
            [product_model] => HFJ5G1.5
            [product_type] => plat
            [product_return] => graviteits

        )

    [2] => Array
        (
            [product_id] => 2
            [product_model] => HHJ5S2.5
            [product_type] => holle plunjer
            [product_return] => veer       

        )
    );  //Only 2 are shown here i have around 110 values

And i encoded this to json by

json_encode($array);

The resulted jsonString is something like this

{"1":{"product_id":"1","product_model":"HFJ5G1.5","product_type":"plat","product_return":"graviteits"},"2":{"product_id":"2","product_model":"HHJ5S2.5","product_type":"holle plunjer","product_return":"veer"}}

when i do alert(jsonString.length); the result is 4 But i want the result to be 2 am i doing something wrong .

Answer 1

an object literal has no .length

you can count properties using this method :

var count = 0;

for (i in jsonString) {
    if (jsonString.hasOwnProperty(i)) {
        count++;
    }
}

alert(count); //count shall have length for you

OR

since your array didn't have numeric indices (starting from 0), it assumed you used an associative array , hence they dumped an object of items rather than an array of items .

to turn them to numeric indices, all you have to do is use array_values before encoding them to json:

json_encode(array_values($array));

then the json will be an array.. then you can use length

from this:

Array(
[1] => Array(
        [product_id] => 1
        [product_model] => HFJ5G1.5
        [product_type] => plat
        [product_return] => graviteits
    )
[2] => Array(
        [product_id] => 2
        [product_model] => HHJ5S2.5
        [product_type] => holle plunjer
        [product_return] => veer       
    )
);

it becomes this using array_values(), note the indexes per item:

Array(
[0] => Array(
        [product_id] => 1
        [product_model] => HFJ5G1.5
        [product_type] => plat
        [product_return] => graviteits
    )
[1] => Array(
        [product_id] => 2
        [product_model] => HHJ5S2.5
        [product_type] => holle plunjer
        [product_return] => veer       
    )
);

then encoded to json and stored to jsonString:

jsonString = [
    {
        "product_id": "1",
        "product_model": "HFJ5G1.5",
        "product_type": "plat",
        "product_return": "graviteits"
    },
    {
        "product_id": "2",
        "product_model": "HHJ5S2.5",
        "product_type": "holle plunjer",
        "product_return": "veer"
    }
];

alert(jsonString.length);

Answer 2

Objects do not support length property: alert({}.length); gives undefined and alert([].length); gives 0 . To find the 'length' of the top level you could do it like:

var arr ={"1":{"product_id":"1","product_model":"HFJ5G1.5",
                 "product_type":"plat","product_return":"graviteits"},
          "2":{"product_id":"2","product_model":"HHJ5S2.5",
                "product_type":"holle plunjer","product_return":"veer"}};
var len = 0;
for(var i in arr) len++;
alert(len);

http://jsfiddle.net/uszaV/