Without knowing exactly how the $asana
lib is implemented (link?) my guess would be that the array is not encoded correctly. If sent via url-encoded post data (as opposed to JSON) the array should be comma-delimited. PHP may do something else like followers[]=1&followers[]=2
when it should be followers=1,2
.
Try doing something like "followers" => implode(",", $arrayOfIds)
, or check the code of the library to see how it encodes arrays. Additionally, including the actual HTTP request/response would help figure out what's going in. There are many ways to get this - your library may include a verbose/debugging mode, but if all else fails you can always use something like Charles Proxy, Wireshark, Ettercap, etc.