Add links to articles from unpaywall

[elizoller]

Use the unpaywall api to look up anything with a DOI) and display links to open access copies if available
https://unpaywall.org/products/api

[scottythered]

This requires sudo apt install php-curl:

<?php
function callUnpayApi($doi){
  $curl = curl_init();
  $query = "https://api.unpaywall.org/v2/" . $doi . "[email protected]";
  curl_setopt($curl, CURLOPT_URL, $query);
  curl_setopt($curl, CURLOPT_HTTPHEADER, array('Accept: application/json'));
  curl_setopt($curl, CURLOPT_RETURNTRANSFER, true);

  // EXECUTE:
  $result = curl_exec($curl);
  curl_close($curl);
  $response = json_decode($result, false);
  if (property_exists($response, 'HTTP_status_code')) {
    return null;
  } else {
    return $response->best_oa_location->url;
  }
}

[elizoller]

I ended up commenting taking this out because doing this through PHP caused more slowness of loading entities. I think the best route forward would be to use a JS component to do this asynchronously.