Ajax: I can't get data from PHP by using json_encode

Question

I am having issues retrieving data from PHP by using Ajax. I am stuck and have been spending lots of time trying to find out where the problem is.

Here is my php code:

        <?php //ajax/default_chart_numbers.php
        require_once '../core/db_connection.php';
        $lotto = new Lotto();
        $ultimo_concurso=$lotto->ultimo_concurso('foo');
        $ultimos_numeros_m=$lotto->ultimos_numeros('bar');

        $R1m=$ultimos_numeros_m[1];
        $R2m=$ultimos_numeros_m[2];
        $R3m=$ultimos_numeros_m[3];
        $R4m=$ultimos_numeros_m[4];
        $R5m=$ultimos_numeros_m[5];
        $R6m=$ultimos_numeros_m[6];
        $R7m=$ultimos_numeros_m[7];

        //preparing json
  $json=array('y'=>$ultimo_concurso,'n1'=>$R1m,'n2'=>$R2m,'n3'=>$R3m,'n4'=>$R4m,'n5'=>$R5m,'n6'=>$R6m);
        print json_encode($json,true);
        ?>

The output of the PHP file is:

{"y":"2745","n1":"1","n2":"13","n3":"19","n4":"29","n5":"41","n6":"46"}

And here is the jQuery code:

<script>
$(document).ready(function(){
    /*Retriving data from PHP file*/
    $.ajax({
        url: "ajax/default_chart_numbers.php",
        cache: false, 
        dataType: "json",
        timeout:3000,
        success : function (response, textS, xhr) {
            alert("everything ok :)");
        },
        error : function (xmlHttpRequest, textStatus, errorThrown) {
            alert("Error " + errorThrown);
             if(textStatus==='timeout')
              alert("request timed out");
        },
        complete: function(data){
            y=data.y;
            alert('The id number is '+ y);
        }
    });
});
</script>

When executing, the value is undefined. I mean, the alert i get is The id number is undefined.

What am i missing?

You must be getting an alert from either the error or the success handler as well? — adeneo
– adeneo, Commented Mar 30, 2014 at 16:44

adeneo · Accepted Answer · 2014-03-30 16:43:01Z

2

There's no true in json_encode, there is in json_decode to get an array, but now you're creating a string

change

print json_encode($json,true);

to

echo json_encode($json);

and the complete handler doesn't get the data, it has two arguments, the XHR object and the statuscode, the success handler gets the data

$.ajax({
    url: "ajax/default_chart_numbers.php",
    cache: false, 
    dataType: "json",
    timeout:3000,
    success : function (data) {
        y=data.y;
        alert('The id number is '+ y);
    },
    error : function (xmlHttpRequest, textStatus, errorThrown) {
         alert("Error " + errorThrown);
         if(textStatus==='timeout')
             alert("request timed out");
    }
});

answered Mar 30, 2014 at 16:43

adeneo

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Comments

Jens A. Koch · Accepted Answer · 2014-03-30 16:53:32Z

1

On PHP side, send the JSON with:

header('Content-Type: application/json');
echo json_encode($json);

Maybe log the incoming data to the console:

inside success: add an console.log(response)
inside complete: add an console.log(data.y)

edited Mar 30, 2014 at 16:53

answered Mar 30, 2014 at 16:44

Jens A. Koch

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Comments

Maarten van Middelaar · Accepted Answer · 2014-03-30 16:48:36Z

-1

This is missing: https://api.jquery.com/jQuery.parseJSON/

try using:

 result = $.parseJSON (data);

result.y has your value

answered Mar 30, 2014 at 16:48

Maarten van Middelaar

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2 Comments

adeneo Over a year ago

No it's not, the dataType is set to JSON, so it's automatically parsed, parsing it again will lead to errors.

Maarten van Middelaar Over a year ago

@adeneo Ah, yes I overlooked that one. Well said.

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