JSON with arrays

Question

I'm trying to return two arrays from a PHP with a JSON object.

Here's my PHP code:

$return = array();
$return += array('val1' => '1',
                 'val2' => '2',
                 'val3' => '3');
$tab = array();                 
for($i=0; $i<3; $i++)
{
    $val = "table1 " . $i;
    array_push($tab, array('tab1' => $val));
}
$return += $tab;

$tab = array();
for ($i = 0; $i < 5; $i++) {
    $val = "table2 " . $i;
    array_push($tab, array('tab2' => $val));
}
$return += $tab;
echo json_encode($return);

and here's my JS code:

console.log("val1=" + data.val1);
console.log("val2=" + data.val2);
console.log("val3=" + data.val3);
for(var i=0; i<3; i++)
console.log("tab1_" + i + "=" + data[i].tab1);
for (var i = 0; i < 5; i++)
console.log("tab2_" + i + "=" + data[i].tab2);

And here's what I get on console:

val1=1
val2=2
val3=3
tab1_0=table1 0
tab1_1=table1 1
tab1_2=table1 2
tab2_0=undefined
tab2_1=undefined
tab2_2=undefined
tab2_3=undefined
tab2_4=undefined

Why can't I add to arrays to the JSON object? What am I doing wrong? Thank you for your help.

Have you tried to print_r($return); to see if your array holds the expected data? — user8034901
– user8034901, Commented Dec 18, 2018 at 11:09
Look at the print_r() and you will see the array you create is not what you think it is — RiggsFolly
– RiggsFolly, Commented Dec 18, 2018 at 11:13
To match the array you are creating change for (var i=0;i<5;i++) to for (var i=3;i< 8;i++) — RiggsFolly
– RiggsFolly, Commented Dec 18, 2018 at 11:16

miken32 · Accepted Answer · 2018-12-18 17:39:42Z

The + and += operators often don't work as expected when combining arrays. If the keys in the second array are already present in the first array, they will be skipped. Your two $tab arrays both had keys 0, 1, and 2 so they weren't being added. Instead, change

$return += $tab;

to

$return = array_merge($return, $tab);

which should finally be something like this:

$return = array();
$return += array('val1' => '1',
                'val2' => '2',
                'val3' => '3');

$tab = array();
for($i=0; $i<3; $i++)
{
    $val = "table1 " . $i;
    array_push($tab, array('tab1' => $val));
}
$return = array_merge($return, $tab);

$tab = array();
for ($i = 0; $i < 5; $i++) {
    $val = "table2 " . $i;
    array_push($tab, array('tab2' => $val));
}
$return = array_merge($return, $tab);

echo json_encode($return);

and the result should be what you are expecting:

    {
    "0": {
        "tab1": "table1 0"
    },
    "1": {
        "tab1": "table1 1"
    },
    "2": {
        "tab1": "table1 2"
    },
    "3": {
        "tab2": "table2 0"
    },
    "4": {
        "tab2": "table2 1"
    },
    "5": {
        "tab2": "table2 2"
    },
    "6": {
        "tab2": "table2 3"
    },
    "7": {
        "tab2": "table2 4"
    },
    "val1": "1",
    "val2": "2",
    "val3": "3"
}

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