How do I return JSON data compatible with the Boost module?

Question

In a custom module a, I return a JSON string that needs to be compatible with the Boost module.

My first try was using the following code:

if ((isset($_SERVER['HTTP_X_REQUESTED_WITH']) && 'XMLHttpRequest' == $_SERVER['HTTP_X_REQUESTED_WITH']) || strpos($_SERVER['REQUEST_URI'], '?json') !== FALSE) {
  header('Cache-Control: no-cache, must-revalidate');
  header('Content-type: application/json', true);
  $json = loadData();
  die(json_encode($json));
}

This is obviously that this output won't be cached. Than I replaced the line with die() with the following one:

return drupal_json_output(($json));

This works, but it is not cached. I enabled the JSON output in Boost, but nothing happens.

What should I try?

---

Removing the two header lines does not change anything. The function drupal_json_output adds the Content-Type: application/json. But I belive that boost only accepts text/javascript. Also if I override the Content-Type again nothing will be cached.

Answer 1

You need to add

module_invoke_all('exit');

to the template-file, immediately prior to the exit or die statement. This will trigger the boost-module's code that stores the generated output in a cache-file. Additionally, you need to change the content-type to text/javascript.

Answer 2

Why do you need to cache JSON output? Anyhow, try removing header('Cache-Control: no-cache, must-revalidate'); and see what happens.

Answer 3

Boost currently doesn't support application/json Content-Type. See this issue for details and patches.

Answer 4

This might help others who are trying to have Boost cache JSON data.

Boost wont cache "application/json", but there are settings to cache TEXT/JAVASCRIPT AJAX request of type "text/javascript"

One problem you are going to find with : drupal_json_output() It uses : drupal_add_http_header('Content-Type', 'application/json');

So a solution you can try is this :

$data = array("hello","world");
drupal_add_http_header('Content-Type', 'text/javascript');
echo drupal_json_encode($data);
drupal_exit();

So if you have Boost "AJAX/JSON SETTINGS" enabled it should now cache the data.