PHP json_encoding datas with parent and child categories

Question

Iam trying with the json_encoding for about two hours but iam not getting the output as required. Actually this is a requirement for the mobile application developer who is asking in the format which i will explain here.The code below is what i have tried:

include_once("class_connection.php");

//Getting the Parent Category

$sqlStr = mysql_query("select catname , id from `category` where `parentid`='0'");
$jsonArray = array();

while ($fetchStr = mysql_fetch_assoc($sqlStr)) {

    $jsonArray[] = array("ParentCategory" => $fetchStr["catname"]);
        $id = $fetchStr['id'];

    //Getting child categories from the above parent

    $sqlChildStr = mysql_query("SELECT catname,id,parentid FROM `category` where `parentid`='$id'");

    while ($fetchchildStr = mysql_fetch_assoc($sqlChildStr)) {

        $jsonArray[] = array("ChildCategory" => $fetchchildStr["catname"]);
    }

}

echo json_encode(array("JsonOutput" => $jsonArray)) . "<br />";

The Output is :

"JsonOutput":[{"ParentCategory":"Animals"},{"ChildCategory":"Bear"},{"ChildCategory":"Deer"},{"ChildCategory":"Dolphins"},
{"ParentCategory":"Art"},{"ChildCategory":"Hand Painting"},{"ChildCategory":"Painting"},{"ChildCategory":"3D"},{"ChildCategory":"Abstract"}]}

Here , in the above output the parent category array is empty without its child category array. I want to store all the child category array in its parent category array and finally i have to store both parent and child category into the JsonOutput array so i want the output as

"JsonOutput":[{
"ParentCategory":"Animals" : [{
    {"ChildCategory":"Bear"},{"ChildCategory":"Deer"},{"ChildCategory":"Dolphins"}
]}
"ParentCategory":"Arts" : [{
    {"ChildCategory":"Hand Painting"},{"ChildCategory":"Painting"},{"ChildCategory":"3D"}, {"ChildCategory":"Abstract"}
]}
]}

Answer 1

You probably need to do this (only the important bits are shown):

$jsonArray = array();
while ($parentCat = mysql_fetch_assoc($sqlStr)) {
    $temp = array(
        "ParentCategory" => $parentCat["catname"]
    );
    while ($childCat = mysql_fetch_assoc($sqlChildStr)) {
        $temp["ChildCategory"][] = array(
            "ChildCategory" => $childCat["catname"]
        );
    }
    $jsonArray[] = $temp;
}

I used a temporary variable for storing and manipulating the parent category. This gets added to the main array at the end of loop.