Retrieving array keys from JSON input - php

Question

I have this array:
$json = json_decode('
{"entries":[
{"id": "29","name":"John", "age":"36"},
{"id": "30","name":"Jack", "age":"23"}
]}
');
and I am looking for a PHP "for each" loop that would retrieve the key names under entries, i.e.:
id
name
age
How can I do this?

Answer 1

Try it
foreach($json->entries as $row) {
foreach($row as $key => $val) {
echo $key . ': ' . $val;
echo '<br>';
}
}
In the $key you shall get the key names and in the val you shal get the values

Answer 2

You could do something like this:
foreach($json->entries as $record){
echo $record->id;
echo $record->name;
echo $record->age;
}
If you pass true as the value for the second parameter in the json_decode function, you'll be able to use the decoded value as an array.

Answer 3

I was not satisfied with other answers so I add my own. I believe the most general approach is:
$array = get_object_vars($json->entries[0]);
foreach($array as $key => $value) {
echo $key . "<br>";
}
where I used entries[0] because you assume that all the elements of the entries array have the same keys.
Have a look at the official documentation for key: http://php.net/manual/en/function.key.php

Answer 4

You could try getting the properties of the object using get_object_vars:
$keys = array();
foreach($json->entries as $entry)
$keys += array_keys(get_object_vars($entry));
print_r($keys);

Answer 5

foreach($json->entries[0] AS $key => $name) {
echo $key;
}

Answer 6

$column_name =[];
foreach($data as $i){
foreach($i as $key => $i){
array_push($column_name, $key);
}
break;
}

Answer 7

Alternative answer using arrays rather than objects - passing true to json_decode will return an array.
$json = '{"entries":[{"id": "29","name":"John", "age":"36"},{"id": "30","name":"Jack", "age":"23"}]}';
$data = json_decode($json, true);
$entries = $data['entries'];
foreach ($entries as $entry) {
$id = $entry['id'];
$name = $entry['name'];
$age = $entry['age'];
printf('%s (ID %d) is %d years old'.PHP_EOL, $name, $id, $age);
}
Tested at https://www.tehplayground.com/17zKeQcNUbFwuRjC