Create JSON with specific format using PHP - php

Question

I have a table in my server database with the following columns:
|---category--|---name---|---description---|
So, lets say for example that we have the following data inside the table:
|---CategoryA--|---name1---|---description1---|
|---categoryB--|---name2---|---description2---|
|---categoryA--|---name3---|---description3---|
|---categoryA--|---name4---|---description4---|
I would like to create a .php file, and when i call it from my Android app i would like to get a JSON as response. The json file would like to have the following format:
{
"CategoryA":[
{"name":"name1","description":"description1"},
{"name":"name3","description":"description3"},
{"name":"name4","description":"description4"}
],
"KatigotiaB":[
{"name":"name2","description":"description2"}
]
}
I have created a .php file that returns me the data in JSON format, but not in the specific format i want. Here is my .php file:
<?php
header('content-type: text/html; charset=utf-8');
try {
$pdo = new PDO('mysql:host=****;dbname=****', '****', '****', array(PDO::MYSQL_ATTR_INIT_COMMAND => "SET NAMES utf8"));
$pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
} catch(PDOException $e) {
echo 'ERROR: ' . $e->getMessage();
}
$stmt = $pdo->prepare("SELECT * FROM `db`.`table`;");
$stmt->execute();
$results = array();
while ($obj = $stmt->fetch(PDO::FETCH_ASSOC)) {
array_push($results, $obj);
}
function replace_unicode_escape_sequence($match) {
return mb_convert_encoding(pack('H*', $match[1]), 'UTF-8', 'UTF-16BE');
}
$str = preg_replace_callback('/\\\\u([0-9a-f]{4})/i', 'replace_unicode_escape_sequence', json_encode($results));
echo $str;
?>
and the result is:
[{"category":"CategoryA","name":"name1","description":"description1"},
{"category":"CategoryB","name":"name2","description":"description2"},
{"category":"CategoryA","name":"name3","description":"description3"},
{"category":"CategoryA","name":"name4","description":"description4"}]
As i'm an Android developer and my php knowledge is limited, how could i recreate my .php file in order to get the correct JSON format?
UPDATE:
that works
foreach ($nameDescriptionPairs as $nameDescriptionPair) {
$result[$row['category']][] = array(
'name' => $nameDescriptionPair['name'],
'description' => $nameDescriptionPair['description']
);
}

Answer 1

Solution #1 (simple):
<?php
$host = 'localhost';
$database = '******';
$user = '******';
$password = '******';
$result = [];
try {
$pdo = new PDO(
"mysql:host=$host; dbname=$database;",
$user,
$password,
[PDO::MYSQL_ATTR_INIT_COMMAND => "SET NAMES utf8"]
);
$stmt = $pdo->prepare("SELECT category, name, description FROM `YOUR_TABLE_HERE`");
$stmt->execute();
while ($row = $stmt->fetch(PDO::FETCH_ASSOC)) {
$result[$row['category']][] = [
'name' => $row['name'],
'description' => $row['description'],
];
}
} catch (Exception $e) {
echo 'ERROR: ' . $e->getMessage();
}
header('content-type: application/json; charset=utf-8');
echo json_encode($result);
Solution #2 (geeky):
One note to my code: I used hex conversion to prevent problems with quotes. Thus, even if any column has any number of ", the code will work fine.
<?php
function hexToStr($hex) {
$string = '';
for ($charIter = 0; $charIter < strlen($hex) - 1; $charIter += 2) {
$string .= chr(hexdec($hex[$charIter] . $hex[$charIter + 1]));
}
return $string;
}
//----------------------
$host = 'localhost';
$database = '******';
$user = '******';
$password = '******';
$result = [];
try {
$pdo = new PDO(
"mysql:host=$host; dbname=$database;",
$user,
$password,
[PDO::MYSQL_ATTR_INIT_COMMAND => "SET NAMES utf8"]
);
$query = <<<QUERY
SELECT category, CONCAT('[', GROUP_CONCAT( CONCAT( '{"name":"', hex( name ) , '", "description":"', hex( description ) , '"}' ) ), ']') raw_json
FROM `YOUR_TABLE_HERE`
GROUP BY category
QUERY;
$stmt = $pdo->prepare($query);
$stmt->execute();
while ($row = $stmt->fetch(PDO::FETCH_ASSOC)) {
$nameDescriptionPairs = json_decode($row['raw_json'], true);
foreach ($nameDescriptionPairs as $nameDescriptionPair) {
$result[$row['category']][] = [
'name' => hexToStr($nameDescriptionPair['name']),
'description' => hexToStr($nameDescriptionPair['description'])
];
}
}
} catch (Exception $e) {
echo 'ERROR: ' . $e->getMessage();
}
header('content-type: application/json; charset=utf-8');
echo json_encode($result);

Answer 2

One major issue is you're setting the content-type to text/html. You're not printing HTML, this should be set to JSON:
header('content-type: application/json; charset=utf-8');
Not sure if it has any effect, but your callback is unnecessary:
$str = preg_replace_callback('/\\\\u([0-9a-f]{4})/i', 'replace_unicode_escape_sequence', json_encode($results));
If you truly don't want json_encode to escape unicode, use the JSON_UNESCAPED_UNICODE option found here: http://php.net/manual/en/function.json-encode.php
$str = json_encode($results, JSON_UNESCAPED_UNICODE);
Beyond that, you could also use JSON_PRETTY_PRINT to format it, but line breaks and such shouldn't matter to the app interpreting the JSON if it is made aware that it is JSON (what setting content-type correctly should do).