unix> curl -X POST --data @- --dump - http://localhost:8529/_api/document?collection=products
{ 1: "World" }

HTTP/1.1 400 Bad Request
content-type: application/json; charset=utf-8

{ 
  "error" : true, 
  "errorMessage" : "expecting attribute name", 
  "code" : 400, 
  "errorNum" : 600 
}