Initial implementation of function to return data for / and /data

endpoints under /rest/.

/rest/ returns:

 1) default_version of the interface and supported_version array
 2) list of links with rel and uri properties that indicate
    what assets are available under /rest. E.g. /rest/data

/data returns:

  a list of possible assets (e.g. issue, user, keyword, status)
  and links for accessing those assets.

E.G.

  {
  "data": {
    "keyword": {
      "link": "https://example.net/demo/rest/data/keyword"
    },
    "user": {
      "link": "https://example.net/demo/rest/data/user"
    }, ...
  }
}

Both of these are currently hand coded. Others will be doing more
development on the rest interface. These two examples are meant to
spark discussion on what the payloads returned by the rest interface
should look like and give some ideas around HATEOAS.

Author: rouilj

roundup/rest.py

@@ -1166,6 +1166,42 @@ def option_attribute(self, class_name, item_id, attr_name, input):
         )
         return 204, ""
 
+    @Routing.route("/")
+    @_data_decorator
+    def describe(self, input):
+        """Describe the rest endpoint"""
+        result = {
+            "default_version": "1",
+            "supported_versions": [ "1" ],
+            "links": [ { "uri": self.base_path +"/summary",
+                        "rel": "summary"},
+                       { "uri": self.base_path,
+                         "rel": "self"},
+                       { "uri": self.base_path + "/data",
+                         "rel": "data"}
+                   ]
+        }
+
+        return 200, result
+
+    @Routing.route("/data")
+    @_data_decorator
+    def data(self, input):
+        """Describe the sublements of data
+
+           FIXME: should have a key for every element under data in
+                  the schema the user can access.
+           This is just an example.
+        """
+        result = {
+            "issue": { "link": self.base_path + "/data/" + "issue" },
+            "status": { "link": self.base_path + "/data/" + "status" },
+            "keyword": { "link": self.base_path + "/data/" + "keyword" },
+            "user": { "link": self.base_path + "/data/" + "user" }
+        }
+
+        return 200, result
+
     @Routing.route("/summary")
     @_data_decorator
     def summary(self, input):