d3 - Uncaught TypeError: data.forEach is not a function

Question

I am working with a scatter plot in d3. I am successfully connected to my database with the php script below but when I run my d3 code I get the error:

Uncaught TypeError: data.forEach is not a function

On the connection call to the php script in my d3 code:

d3.json("connection.php", function(error, data){
if (error) throw error;
data.forEach(function(d) {
    d['TITLE'] = d.TITLE.toString();
    d['YEAR'] = +d['YEAR'];
    d['counter'] = +d['counter'];
    console.log(data.query1Results);
    console.log(data.query2Results);
    })

Here is my php script:

<?php
$username = "xxx"; 
$password = "";   
$host = "xxxx";
$database="xxxx";

$server = mysql_connect($host, $username, $password);
$connection = mysql_select_db($database, $server);

$data = array(
'query1Results' => array(),
'query2Results' => array()
);

$myquery = "SELECT  `ID`, `TITLE`, `YEAR`, `In_library` FROM  `papers` where In_library = 1";

$query1 = mysql_query($myquery);

if ( ! $query1 ) {
    echo mysql_error();
    die;
}

for ($x = 0; $x < mysql_num_rows($query1); $x++) {
    $data['query1Results'][] = mysql_fetch_assoc($query1);
}

$query2 = mysql_query("SELECT `ID_to`, count(*) as `counter` from `citations` group by `ID_to` DESC");

if ( ! $query2 ) {
    echo mysql_error();
    die;
}

for ($x = 0; $x < mysql_num_rows($query2); $x++) {
    $data['query2Results'][] = mysql_fetch_assoc($query2);
}

echo json_encode($data);     

mysql_close($server);


?>

Would be very grateful if anyone could tell me what is causing this error and possible solutions as I cant see where I have gone wrong (probably because I have been looking at is for so long!) thanks in advance.

Answer 1

You would have to create an empty array before the d3.json() and then put the data into the empty array like this:

 var arr=[];
   d3.json("connection.php", function(data){
       arr = data;

        arr.forEach((d)=>{
d['TITLE'] = d.TITLE.toString();
d['YEAR'] = +d['YEAR'];
d['counter'] = +d['counter'];
console.log(data.query1Results);
console.log(data.query2Results);
});
});