从html获取php生成的json

Question

I have a form in an html file which sends data to a php file. That php file selects from the database, transforms the results into a json file and sends it back to the html file.

I would like to know how can I get the json from the php; I do get the reply (from the network tab in the inspection menu), but I don't know how to get it (to echo/alert/make a chart with it). Thanks in advance!

This is my code to send the data:

<script type="text/javascript">
    $( function() {
        $( ".datepicker" ).datepicker({
            minDate: new Date(2015, 8 - 1, 25),
            maxDate: "0"
        });
    });

$(function () {
    // On form's submit, takes both input's values...
    $('form').on('submit', function (e) {
        var from = $("#from").val();
        var to = $("#to").val();
        // ...to compare them and displays an error if "to" is smaller than "from"
        if(Date.parse(from) > Date.parse(to)){
            alert("Invalid Date Range");
        }
        else{
            e.preventDefault();
            $.ajax({
                type: 'post',
                url: 'classes/Select.php',
                data: $('form').serialize(),
                success: function () {
                    alert('data sent');
                }
            });
        }
    });
});
</script>

And this is the php part that makes the json (left out all the mysql part and such):

while ($arr = $query->fetch(PDO::FETCH_ASSOC)) {
    echo json_encode($arr);

Answer 1

In your javascript ajax call code, you probably have a success: key. Try:

success: function(data) { console.log(data); }

Answer 2

if you get a JSON string use json_decode($json) and you get the value you want:

$json = '{"key-example": 12345}';

$obj = json_decode($json);
print $obj->{'key-example'}; // 12345

Answer 3

Since you are using a loop in your php, create an array that will hold the results, when the loop finishes echo the results with json_encode ;

$results = [];
while ($arr = $query->fetch(PDO::FETCH_ASSOC)) {
    $results[] = $arr;
}
echo json_encode($results);

Then in your javascript

    $.ajax({
       type: 'post',
       url: 'classes/Select.php',
       data: $('form').serialize(),
       success: function(data) {
           var results = JSON.parse(data); // convert the results to json
           console.log(results);
       }
   });