PHP encode JSON (2 dimensional array)

Question

I am querying a table that return to fields(message_type & percentage). I use PHP to encode the json data, here is how i do it

$json = array();
while ($row = odbc_fetch_array($rs)) {
  $json[][] = $row;
}
echo json_encode($json);

output :

[ [ { "message_type" : "bullying",
      "percentage" : "60"
    } ],
  [ { "message_type" : "cheating",
      "percentage" : " 14"
    } ],
  [ { "message_type" : "Stress",
      "percentage" : "16"
    } ],
  [ { "message_type" : "Gang",
      "percentage" : "7"
    } ]
]

As you can see json_encode function is adding curly braces, quotes and the object key name.

What I want is to parse the json as two dimensional array only, here is the desired output:

[
  ["bullying", 60],
  ["harrassment", 9],
  ["cheating", 14],
  ["Stress", 16],
  ["Gang", 7]
]

I also tried to encode it manually but I could not get the result I need.

Solution

PHP's json_encode() uses a certain amount of magic to determine whether a given vector is encoded as a JSON object or an array, but the simple rule is this: If the array has contiguous, zero-indexed, numeric keys, it will be encoded as an array. Any other vector (object or associative array) will be encoded as an object.

Because you are using odbc_fetch_array(), your result rows are returned as an associative array with the keys being the column names. To get the result you want you have 3 options:

Pass the result rows through array_values():

$json[] = array_values($row);

Manually construct the individual arrays:

$json[] = array($row['message_type'], $row['percentage']);

Or probably the best option is to use odbc_fetch_row() instead, which will return indexed arrays straight away:

while ($row = odbc_fetch_row($rs)) {
    $json[] = $row;
}