通过JavaScript迭代/解析JSON对象

Question

I'm having a problem with jQuery/Ajax/JSON. I'm using a jQuery ajax post like so...

$.ajax({
  type: "POST",
  dataType: "json",
  url: "someurl.com",
  data: "cmd="+escape(me.cmd)+"&q="+q+"&"+me.args,
  success: function(objJSON){
    blah blah...
  }
});

It's my understanding that this will return a JavaScript JSON object? The text that the ajax post produces is this (I believe this is valid JSON)...

{
  "student":{
    "id": 456,
    "full_name": "GOOBER, ANGELA",
    "user_id": "2733245678",
    "stin": "2733212346"
  },
  "student":{
    "id": 123,
    "full_name": "BOB, STEVE",
    "user_id": "abc213",
    "stin": "9040923411"
  }
}

I can't seem to figure out how to parse through the JSON object returned by the jQuery ajax post... basically I want to loop through and make a div out of each student returned like so...

$("<div id=\"" + student.id + "\">" + student.full_name + " (" + student.user_id + " - " + student.stin + ")</div>")

I just can't seem to figure out how to do it...

Thanks!

Answer 1

Your JSON object is incorrect because it has multiple properties with the same name. You should be returning an array of "student" objects.

[
   {
     "id": 456,
     "full_name": "GOOBER ANGELA",
     "user_id": "2733245678",
     "stin": "2733212346"
   },
   {
     "id": 123,
     "full_name": "BOB, STEVE",
     "user_id": "abc213",
     "stin": "9040923411"
   }
]

Then you can iterate over it as so:

 for (var i = 0, len = objJSON.length; i < len; ++i) {
     var student = objJSON[i];
     $("<div id=\"" + student.id + "\">" + student.full_name + " (" + student.user_id + " - " + student.stin + ")</div>")...
 }

Answer 2

There's a problem with that JSON - the outer curly braces should be square brackets, as you want a list, not a map (aka object). With all objects in the map having the same key, it won't parse right - the last value will overwrite the previous under most parsers.

You want:

[
  {
    "id": 456,
    "full_name": "GOOBER, ANGELA",
    "user_id": "2733245678",
    "stin": "2733212346"
  },
  {
    "id": 123,
    "full_name": "BOB, STEVE",
    "user_id": "abc213",
    "stin": "9040923411"
  }
]

or alternatively a map with different keys:

{
  "456":{
    "id": 456,
    "full_name": "GOOBER, ANGELA",
    "user_id": "2733245678",
    "stin": "2733212346"
  },
  "123":{
    "id": 123,
    "full_name": "BOB, STEVE",
    "user_id": "abc213",
    "stin": "9040923411"
  }
}

You'd be better off using $.getJSON, which is a specialised version of $.ajax for this purpose.

$.getJSON("someurl.com", function(students) {
  $.each(students, function() { 
    $("<div id=\"" + student.id + "\">" + student.full_name + " (" + student.user_id + " - " + student.stin + ")</div>").appendTo($container);
  });
});

Answer 3

The JSON you have currently will not work because the second "student" effectively replaces the first, since these are just properties in an object.

If you can control the JSON output, change it to:

{
  "student":[{
    "id": 456,
    "full_name": "GOOBER, ANGELA",
    "user_id": "2733245678",
    "stin": "2733212346"
    },{
    "id": 123,
    "full_name": "BOB, STEVE",
    "user_id": "abc213",
    "stin": "9040923411"
  }]
}

Then you have an an array which you can loop over:

for(var i=0; i<objJSON.student.length; i++) {
  ...objJSON.student[i]...
  }

Answer 4

var data = '[
  {
      "id": 456,
      "full_name": "GOOBER, ANGELA",
      "user_id": "2733245678",
      "stin": "2733212346"
  },
  {
      "id": 123,
      "full_name": "BOB, STEVE",
      "user_id": "abc213",
      "stin": "9040923411"
   }
]';

$.each(data, function(index, val) {
    alert(val.id);
    alert(val.full_name);
    alert(val.user_id);
    alert(val.stin);    
})