README.rst

link-header

This system helps to parse Link HTTP header from API responses. Good example of the usage of this header is the documentation of GitHub's API:

https://developer.github.com/v3/#link-header

Usage

Library provides two ways of parsing the header. Simplest one is link-header:parse function:

CL-USER> (link-header:parse "<https://api.github.com/user/repos?page=3&per_page=100>; rel=\"next\",
  <https://api.github.com/user/repos?page=50&per_page=100>; rel=\"last\"")
(:LAST "https://api.github.com/user/repos?page=50&per_page=100" :NEXT
 "https://api.github.com/user/repos?page=3&per_page=100")
CL-USER> (getf * :next)
"https://api.github.com/user/repos?page=3&per_page=100"

But if you are using great Dexador library, to make HTTP requests, then you can use link-header:with-links macro to process values, returned by dexador:get.

CL-USER> (link-header:with-links (response next-link)
           (dex:get "https://api.github.com/repos/sbcl/sbcl/commits")
           (values (length response) next-link))
92847 (17 bits, #x16AAF)
"https://api.github.com/repositories/1890957/commits?page=2"

As you can see, next-link was bound to the next link from the header. Also, other parameters are supported:

• response;
• status-code;
• headers;
• uri;
• xxx-link - any parameter with -link header will be bound to corresponding part of the Link header or nil.

Here is full example:

CL-USER> (link-header:with-links (response status-code headers uri next-link last-link)
           (dex:get "https://api.github.com/repos/sbcl/sbcl/commits")
           (values (length response)
                   uri
                   status-code
                   headers
                   next-link
                   last-link))
92847 (17 bits, #x16AAF)
#<QURI.URI.HTTP:URI-HTTPS https://api.github.com/repos/sbcl/sbcl/commits>
200 (8 bits, #xC8, #o310, #b11001000)
#<HASH-TABLE :TEST EQUAL size 24/60 #x30200AD6F3DD>
"https://api.github.com/repositories/1890957/commits?page=2"
"https://api.github.com/repositories/1890957/commits?page=452"