如何读取我的 JSON 文件？

Question

I've been working on it for hours, reading stackoverflow articles but I cannot figure it out. I'm trying to read information from a .json file into an array. The .json file has one key mapped to a huge array of JSON values...here is the code:

JSON file:

{
"SDpairs":
[{"SD Pair":"Afghanistan -
Azerbaijan","Source":"Afghanistan","Dest":"Algeria","Flow":5,"Capacity":16},
{"SD Pair":"Afghanistan - 
Azerbaijan","Source":"Afghanistan","Dest":"Australia","Flow":3,"Capacity":3},
{"SD Pair":"Afghanistan - Azerbaijan","Source":"Afghanistan","Dest":"Austria","Flow":12,"Capacity":12},
{"SD Pair":"Afghanistan - Azerbaijan","Source":"Afghanistan","Dest":"Belgium","Flow":3,"Capacity":10},

etc...

JavaScript method:

$.getJSON("SDpairs.json", function(data) {

    var str = JSON.stringify(data);
    var json = JSON.parse(str);
    console.log(json);
    console.log("Type of 'json': " + typeof json);

    for (var edge in json["SDpairs"]) {
        console.log(json["SDPairs"][edge]);
        console.log("Type of 'edge': " + typeof edge);
        if (currPair == null) {
            // If it is the first JSON to be read
            currPair = [];
            currPair.push(edge);
        } else if (edge['SD Pair'] == currPair[0]['SD Pair']) {
            // If the JSON is part of the same SD pair as currPair, push into currPair
            currPair.push(edge);
        } else {
            // If it is a new SDpair as compared to currPair
            sdPairs.push(currPair);
            currPair = [];
            currPair.push(edge);
        }
    }

}

EDIT:

Errors:

 Uncaught TypeError: Cannot read property '0' of undefinedinitData @     
 database.js:67(anonymous function) @ index.html:31
 database.js:10 Object
 database.js:11 Type of 'json': object
 database.js:14 Uncaught TypeError: Cannot read property '0' of     
 undefined(anonymous function) @ database.js:14f.Callbacks.o @    
 jquery.min.js:2f.Callbacks.p.fireWith @ jquery.min.js:2w @ 
 jquery.min.js:4f.support.ajax.f.ajaxTransport.c.send.d @ jquery.min.js:4

Update #1:

var sdPairs = [];

var initData = function() {
var currPair = [];

// Create and push arrays of JSONs into sdPairs. 
// Each array contains edges from the same SD Pair
$.getJSON("SDpairs.json", function(data) {

    var num = 0;
    for (var element in data["SDpairs"]) {
        var edge = data["SDpairs"][element];

        if (currPair.length == 0) {
            // If it is the first JSON to be read
            currPair.push(edge);
        } else if (edge['SD Pair'] == currPair[0]['SD Pair']) {
            // If the JSON is part of the same SD pair as currPair, push into currPair
            currPair.push(edge);
        } else {
            // If it is a new SDpair as compared to currPair
            sdPairs.push(currPair);
            currPair = [];
            currPair.push(edge);
        }

        if (num == 0) {
            console.log("Edge is " + edge);
            console.log("edge['SD Pair'] is " + edge['SD Pair']);
        }
        num++;
    }
    sdPairs.push(currPair);
});
console.log(sdPairs.length);
console.log(currPair.length);
}

Answer 1

It looks like you're not getting the right output, for two reasons. You're only comparing keys (not their values) in your for..in loop. You're also losing out on the last processed set of objects when exiting the loop. You should add it at the end.

var sdPairs=[], currPair; // Remember to declare the variables you're using somewhere
for(var name in json["SDpairs"]) {
    var edge = json["SDpairs"][name];
    // The rest of your code
}
sdPairs.push(currPair);
console.log(sdPairs); // Do something with sdPairs now