1 files changed, 57 insertions, 0 deletions
diff --git a/synapse/http/servlet.py b/synapse/http/servlet.py
index d5ccf2742f..a4eb6c817c 100644
--- a/synapse/http/servlet.py
+++ b/synapse/http/servlet.py
@@ -15,6 +15,8 @@
 
 """ This module contains base REST classes for constructing REST servlets. """
 
+from synapse.api.errors import SynapseError
+
 import logging
 
 
@@ -54,3 +56,58 @@ class RestServlet(object):
                     http_server.register_path(method, pattern, method_handler)
         else:
             raise NotImplementedError("RestServlet must register something.")
+
+    @staticmethod
+    def parse_integer(request, name, default=None, required=False):
+        if name in request.args:
+            try:
+                return int(request.args[name][0])
+            except:
+                message = "Query parameter %r must be an integer" % (name,)
+                raise SynapseError(400, message)
+        else:
+            if required:
+                message = "Missing integer query parameter %r" % (name,)
+                raise SynapseError(400, message)
+            else:
+                return default
+
+    @staticmethod
+    def parse_boolean(request, name, default=None, required=False):
+        if name in request.args:
+            try:
+                return {
+                    "true": True,
+                    "false": False,
+                }[request.args[name][0]]
+            except:
+                message = (
+                    "Boolean query parameter %r must be one of"
+                    " ['true', 'false']"
+                ) % (name,)
+                raise SynapseError(400, message)
+        else:
+            if required:
+                message = "Missing boolean query parameter %r" % (name,)
+                raise SynapseError(400, message)
+            else:
+                return default
+
+    @staticmethod
+    def parse_string(request, name, default=None, required=False,
+                     allowed_values=None, param_type="string"):
+        if name in request.args:
+            value = request.args[name][0]
+            if allowed_values is not None and value not in allowed_values:
+                message = "Query parameter %r must be one of [%s]" % (
+                    name, ", ".join(repr(v) for v in allowed_values)
+                )
+                raise SynapseError(message)
+            else:
+                return value
+        else:
+            if required:
+                message = "Missing %s query parameter %r" % (param_type, name)
+                raise SynapseError(400, message)
+            else:
+                return default