Add some simple tools for parsing values out of endpoints

This will help us with some basic validation

vanth/pages/tools.py

@@ -0,0 +1,26 @@
+import functools
+import json
+
+import flask
+
+
+def parse(args):
+    def _decorate(request_handler):
+        @functools.wraps(request_handler)
+        def _parse():
+            values = {}
+            missing_parameters = []
+            for key, converter in args.items():
+                supplied = flask.request.form.get(key)
+                if supplied is None:
+                    missing_parameters.append(key)
+                else:
+                    values[key] = converter(supplied)
+            if missing_parameters:
+                return (json.dumps({'errors': [{
+                    'title' : "Missing required paramter '{}'".format(parameter),
+                    'code'  : "missing-required-paramter",
+                } for parameter in missing_parameters]}), 400, {})
+            return request_handler(values)
+        return _parse
+    return _decorate