select into JSON

follo开发者_如何学编程wing my question

it is posible to select values into my JSon object that mean To list distinct schools where aaa studied

JSON object look like this

[{"name":"aaa","0":"aaa","city":"paris","1":"paris","school":"gtdzh","2":"gtdzh"}, {"name":"bbb","0":"bbb","city":"berlin","1":"berlin","school":"gdezh","2":"gdezh"}, {"name":"ccc","0":"ccc","city":"new york","1":"new york","school":"asdzh","2":"asdzh"}, {"name":"aaa","0":"aaa","city":"sidney","1":"sidney","school":"gtdcv","2":"gtdcv"}, {"name":"bbb","0":"bbb","city":"paris","1":"paris","school":"gtdzh","2":"gtdzh"}]

thank for your help

---

If all of the names can be guaranteed to be unique then you can do something like this:

var data_array = [
{"name":"aaa","0":"aaa","city":"paris","1":"paris","school":"gtdzh","2":"gtdzh"},
{"name":"bbb","0":"bbb","city":"berlin","1":"berlin","school":"gdezh","2":"gdezh"}, 
{"name":"ccc","0":"ccc","city":"new york","1":"new york","school":"asdzh","2":"asdzh"}, 
{"name":"aaa","0":"aaa","city":"sidney","1":"sidney","school":"gtdcv","2":"gtdcv"}, 
{"name":"bbb","0":"bbb","city":"paris","1":"paris","school":"gtdzh","2":"gtdzh"}
];

var l = data_array.length;
var i = 0

// We will use dict to store our output
var dict = {};

// Loop over the entire array
while ( i < l ) {
    // Grab references to everything we need
    var name = data_array[i].name;
    var city = data_array[i].city;

    // If we haven't seen this person before, add them to the dict
    if ( ! Object.prototype.hasOwnProperty.call(dict, name) ) {
        dict[name] = {};
    }

    // Similarly, if we haven't heard of them studying in this city yet
    // add that city to the "dictionary" of cities they've studied in
    // and set the count of times they have studied in that city to 1.
    if ( ! Object.prototype.hasOwnProperty.call(dict[name], city) ) {
        dict[name][city] = 1;
    // Otherwise, increment the number of times they have studied in that city.
    } else {
        dict[name][city] += 1;
    }
    i++;
}

The end result will look something like this:

dict = {
    "aaa": {
        "paris": 1,
        "sidney": 1
    },
    "bbb": {
        "berlin": 1,
        "paris": 1
    },
    "ccc": {
        "new york": 1
    }
};

Of course, there are better ways to go about this if you are doing this sort of thing repeatedly -- everything from changing the way the data is sent over from the server to building or using helper libraries like Underscore to do this sort of data-munging. There are also a few Javascript database implementations out there, but I haven't worked with any of them so I cannot recommend anything in that regard.