使用jQuery .each（）从数据库中读取JSON到组合框中

Question

I need to be able to select a country in a selectbox, and then get all the states from that country.

I'm trying to do something like this: how-to-display-json-data-in-a-select-box-using-jquery

This is my controller:

foreach($this->settings_model->get_state_list() as $state)
{
   echo json_encode(array($state->CODSTA, $state->STANAM));
}

and my javascript:

 $.ajax({
    url: 'settings/express_locale',
    type: 'POST',
    data: { code: location, type: typeLoc },
    success: function (data) {
        console.log(data);
    }
});

console.log shows me something like this:

["71","SomeState0"]["72","SomeState"]["73","SomeState2"]["74","SomeState3"]

So, what i need is to append all states in a new selectbox.

But I'm trying to read this array doing this in the success callback:

$.each(data, function(key,val){
   console.log(val);
});

In the result, each line is a word, like this:

[
 "
 7
 1
 "
 ,
 "
 s
 ....
 ]

Why does that happen, and what am I missing?

Answer 1

JSON is not made of independent blocks. So this will never do:

foreach($this->settings_model->get_state_list() as $state)
{
    echo json_encode(array($state->CODSTA, $state->STANAM));
}

The output will be treated as text, and the iterator will loop the object's elements... which are the single characters.

You need to declare a list, or a dictionary. I have included some examples, depending on how you use the data in the jQuery callback. Note: PHP-side, you may also need to output the proper MIME type for JSON:

$states = array();
foreach($this->settings_model->get_state_list() as $state)
{
    // Option 1: { "71": "SomeState0", "72": "Somestate2", ... }
    // Simple dictionary, and the easiest way IMHO
    $states[$state->CODSTA] = $state->STANAM;

    // Option 2: [ [ "71", "SomeState0" ], [ "72", "SomeState2" ], ... ]
    // List of tuples (well, actually 2-lists)
    // $states[] = array($state->CODSTA, $state->STANAM);

    // Option 3: [ { "71": "SomeState0" }, { "72": "SomeState2" }, ... ]
    // List of dictionaries
    // $states[] = array($state->CODSTA => $state->STANAM);
}

Header('Content-Type: application/json');
// "die" to be sure we're not outputting anything afterwards
die(json_encode($states));

In the jQuery callback, you specify the datatype and content type with charset (this will come in handy as soon as you encounter a state such as the Åland Islands, where a server sending data in ISO-8859-15 and a browser running a page in UTF8 can lead to a painful WTF moment):

        $.ajax({
            url: 'settings/express_locale',
            type: 'POST',
            data: { code: location, type: typeLoc },
            contentType: "application/json; charset=utf-8",
            dataType: "json",
            success: function (data) {
                $("#comboId").get(0).options.length = 0;
                $("#comboId").get(0).options[0] = new Option("-- State --", "");
                // This expects data in "option 1" format, a dictionary.
                $.each(data, function (codsta, stanam){
                   n = $("#comboId").get(0).options.length;
                   $("#comboId").get(0).options[n] = new Option(codsta, stanam);
             });
           },
           error: function () {
                alert("Something went wrong");
           }