How to get Link Headers (for pagination) from API using PHP cURL

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I'm querying an API for a list of results, using PHP and cURL.

In order to enable pagination, the API returns links to the next and previous pages of results, in the header, as HTTP Link Headers. https://www.w3.org/wiki/LinkHeader

When I print_r the object I get back from curl_exec, the links in the header (between angled brackets) are empty. I verify that I should be being returned links, by looking in the Swagger docs. (see example). In the Swagger docs, the links are returned within angle brackets - is there something about the way cURL is getting/returning the headers that means content within angle brackets is lost?

Source code: 

$curl = curl_init("https://api.mendeley.com/datasets?limit=3");
curl_setopt($curl, CURLOPT_HEADER, 1); 
curl_setopt($ch,CURLOPT_ENCODING , "gzip");
$rest = curl_exec($curl);
print_r($rest);

Expected output (from Swagger docs): 

"link": "<https://api.mendeley.com/datasets?marker=0027ea1f-bec6-4581-a967-9a8c75dfba5f&limit=3&fields=results.id&reverse=false&_=1505585347125&order=asc>; rel=\"next\"",

Actual output: 

Link: ; rel="next"
header curl api pagination php
2 Answers

having code like this:

$content = <<<HTML
Link: <meta.rdf>; rel=meta

Content.
HTML;

print_r($content);

shows in browser exactly:

Link: ; rel=meta Content.

because things within angle brackets are considered to be tags and are not rendered. If you use "crtl+u" shortcut to view sourcecode, you will see:

Link: <meta.rdf>; rel=meta

Content.

And this means that everything is working fine, and you have everything you need.

I bet that it's your case.

user_46153310
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