Optimal way to call Page Data via JSON and AJAX

[Neo]

I have a site with a blog section (every blog post is a page), which I don't want to populate in the list view via the ordinary pagination.

Instead, I have written a bit of JS to load the blog posts after each other: in this case always 2 blog posts by the click of a button via $.getJSON(). So I use a JSON file to get my page data from Processwire.

On the ProcessWire site, I have written the following code on the top of my blog.php list view template:

<?php

  $json = array();

  $posts = wire('pages')->find('template=blog-post, sort=-blog_date');

  foreach($posts as $post) {

    $json[] = array(
      'link' => $post->url,
      'date' => $post->blog_date,
      'title' => $post->title
      //'preview' => substr($post->body, 0, 250)
    );

  }

  file_put_contents('posts.json', json_encode($json));

So this basically creates the posts.json file in http://example.com/My_Project/site/templates/posts.json every time the template is accessed. 

This works, the data is populated in the view.

However, I am not sure if this is the best way to approach this considering performance as the json file is created every time the page is requested.

Would appreciate your advice.

 

[LostKobrakai]

Just return json directly like so: http://stackoverflow.com/questions/4064444/returning-json-from-a-php-script

[Neo]

So, basically you would just return the JSON-array without writing it to the file?

Something like 

return json_encode($json);

Using "echo" would directly print it to the page. 

However, in this case I guess I would have to provide the template location in my JS:

$.getJSON('http://localhost/My_Project/blog/',processPreview);

which actually does not work. It does not throw an error, but only works with the actual JSON-file specifically provided as a URL, i.e. http://localhost/My_Project/site/templates/posts.json

 

So I assume the JSON is not returned in the right way?

 

[LostKobrakai]

Make sure you're setting the content-type header, otherwise jquery will handle it as plain text instead of json.

[Neo]

Setting the header in the template will return the page view in plain code:

header('Content-Type: application/json');

So I finally created a new template just for the JSON and didn't put the code directly in blog.php.

This works...

[thetuningspoon]

You can also put it at the very top of the same template file, as long as you do something like this:

if($config->ajax) {
	// Output your json
	exit;
}

 

[adrian]

7 minutes ago, thetuningspoon said:

You can also put it at the very top of the same template file, as long as you do something like this:

if($config->ajax) {
	// Output your json
	exit;
}

 

Don't forget about $this->halt() rather than using exit/die

https://processwire.com/blog/posts/processwire-2.6.8-brings-new-version-of-reno-admin-theme-and-more/#new-this-gt-halt-method-for-use-in-template-files

[thetuningspoon]

If you want to be picky about it 

[bernhard]

On 13.9.2016 at 10:32 PM, adrian said:

Don't forget about $this->halt() rather than using exit/die

https://processwire.com/blog/posts/processwire-2.6.8-brings-new-version-of-reno-admin-theme-and-more/#new-this-gt-halt-method-for-use-in-template-files

what about returning some json data from inside modules? the halt() method only applies to templatefiles.

is there a way to halt any other output inside the admin (inside a module) other than this?

echo json_encode($mydata);
die();

or is it fine to do so?

[arjen]

@bernhard, I've struggled with this in the past too inside ProcessModules. Didn't find another solution but to use " die()". Feels awkward 

[Robin S]

@bernhard, for module AJAX calls I have used a replace hook on ProcessModule::executeEdit. In my JS I send an AJAX request to the module's config page, and in the hook I check that the request is coming via AJAX and has the required GET/POST variable(s) and if so I use $event->replace = true and return my response.

[bernhard]

thank you robin, this seems too complicated for my usecase.

i'm working on a datatables fieldtype and i came up with this solution:

  private function getAjaxData() {
    $config = $this->wire->config;
    $input = $this->wire->input;

    // if the field is set AND the request was done via ajax we return the data of the table
    // if it was only the field variable it could have been requested as single field in a modal
    if($config->ajax AND $input->get->field === $this->name) {
      echo $this->getJSON();
      die();
    }
  }

the data is requested via AJAX and the field is set. the further makes the field always load even if it is set to hidden+ajax - so i always get the json. don't think there's anything bad with this solution, but of course i'm happy to hear if im missing anything...