MySQL query on table structure to make JSON friendly format - php

Question

I want to have a result like this, to expand all nodes and make a defined treeview.
var defaultData = [
{
text: 'Parent 1',
href: '#parent1',
tags: ['4'],
nodes: [
{
text: 'Child 1',
href: '#child1',
tags: ['2'],
nodes: [
{
text: 'Grandchild 1',
href: '#grandchild1',
tags: ['0']
},
{
text: 'Grandchild 2',
href: '#grandchild2',
tags: ['0']
}
]
},
{
text: 'Child 2',
href: '#child2',
tags: ['0']
}
]
},
{
text: 'Parent 2',
href: '#parent2',
tags: ['0']
},
{
text: 'Parent 3',
href: '#parent3',
tags: ['0']
},
{
text: 'Parent 4',
href: '#parent4',
tags: ['0']
},
{
text: 'Parent 5',
href: '#parent5' ,
tags: ['0']
}
];
I've create a table like this, is it correct?
and how to query them in order to have result as above by json_encode the result?

Answer 1

First of all, you need to fix your table. It is highly irregular and text values will not work well with matching in any language. Try a table like this:
------------------------------
| id | parent | desc |
------------------------------
| 1 | 0 | parent 1 |
------------------------------
| 2 | 0 | parent 2 |
------------------------------
| 3 | 0 | parent 1 |
------------------------------
| 4 | 0 | parent 2 |
------------------------------
| 5 | 0 | parent 1 |
------------------------------
| 6 | 1 | child 1 |
------------------------------
| 7 | 1 | child 2 |
------------------------------
| 8 | 6 | Grandchild 1 |
------------------------------
| 9 | 6 | Grandchild 2 |
------------------------------
id and parent should be integer fields and desc can be text/varchar. Root or top level items should have a parent value of zero (0).
Then you can use a script similar to:
$db = new mysqli('127.0.0.1', 'your_db_user', 'your_secure_password', 'your_db_schema');
if( $mysqli->connect_error ) {
echo 'Something went wrong: ' . $mysqli->connect_error;
}
$json = [];
function sanitize_id($id) {
return preg_replace( '/[^a-z0-9]/', '', strtolower($id) );
}
function recursive( $parentId, &$json ) {
global $mysqli;
if ($stmt = $mysqli->prepare("SELECT * FROM your-table WHERE parent = ?")) {
// Bind parent id to query
$stmt->bind_param('i', $parentId);
$results = $stmt->execute();
// Loop over results
while ( $result = $results->fetch_assoc() ) {
// Add result to JSON structure at referenced location
$json[] = [
'text' => $result['desc'],
'href' => '#' . sanitize_id($result['desc']),
'tags' => ['0'], // Are the tags another field?
'nodes' => []
];
// Rerun recusive function to check for and add any children
recursive( $result['id'], $json['nodes'] );
}
$stmt->close();
}
};
recursive(0, $json);
echo json_encode( $json );
$db->close();