Rewrite manually created nested JSON to use PHPs built in functions - php

Question

I have in my table records that are related one to another by a parentId field. When fetching them from the DB I need to create JSON array of objects where the child records are added to 'children' property of parent objects :
[{
//main object
children : [
{
//#1st level children object
children: [
{
//#2nd level children object
}
]
}
]
},
{
(...)
]
But if there are no records with parentId equal to current record, then this property shouldn't be added to the object.
Right now I'm building the JSON string manually :
//first get the parents
$q = 'SELECT * FROM table WHERE parentId = 0';
$r = mysql_query($q);
$x=1;
$nr = mysql_num_rows($r);
while($e = mysql_fetch_array($r)){
if($x==1){
echo '[ { ';
}
else{
echo ' { ';
}
if($e['leaf']==1){
$leaf = 'true';
} else {
$leaf = 'false';
}
echo '"EndDate" : "'.str_replace('T00:00:00','',$e['EndDate']).'",
"Id" : '.$e['Id'].',
"Name" : "'.$e['Name'].'",
"BaselineStartDate" : "'.str_replace('T00:00:00','',$e['BaselineStartDate']).'"';
if($leaf){
echo ',"leaf": '.$leaf.'';
}
childs($e['Id'], $x, $nr);
if($x<$nr){
echo ',';
}
$x++;
}
if($x>1){
echo ']';
}
function childs($id, $x, $nr, $x2='', $nr2=''){
//now see if there are childern
$q2 = 'SELECT * FROM table WHERE parentId = "'.$id.'" ';
$r2 = mysql_query($q2);
$nr2 = mysql_num_rows($r2);
if($nr2>0){
echo ',"children": [ ';
$x2 =1;
while($e2 = mysql_fetch_array($r2)){
if($e2['leaf']==1){
$leaf2 = 'true';
}
else{
$leaf2 = 'false';
}
echo '{
"EndDate" : "'.str_replace('T00:00:00','',$e2['EndDate']).'",
"Id" : '.$e2['Id'].',
"Name" : "'.$e2['Name'].'",
"BaselineStartDate" : "'.str_replace('T00:00:00','',$e2['BaselineStartDate']).'",
"leaf" : "'.$leaf2.'"';
childs($e2['Id'],$x,$nr,'',$x2,$nr2);
if($x2<$nr2){
echo ',';
}
$x2++;
}
echo '] }';
}
else{
echo ',"children" : []}';
}
}
Is there an easy way to make this code more robust using some built-in PHP features like fetch_assoc or something like that?

Answer 1

You should rather..
Fetch the results from the database
Reformat as per the requirement (related code you can use with some alteration PHP Create a Multidimensional Array from an array with relational data
Then finally, json_encode the resulting array