Support websocket methods in View class

src/labthings/views/__init__.py

@@ -1,5 +1,5 @@
 from flask.views import MethodView, http_method_funcs
-from flask import request
+from flask import request, abort
 from werkzeug.wrappers import Response as ResponseBase
 from werkzeug.exceptions import BadRequest
 
@@ -107,19 +107,29 @@ def get_value(self):
         else:  # Unless somehow an HTTP response isn't returned...
             return response
 
+    def _find_request_method(self):
+        meth = getattr(self, request.method.lower(), None)
+        if meth is None and request.method == "HEAD":
+            meth = getattr(self, "get", None)
+
+        # Handle the case of a GET request asking for WS upgrade where
+        # no websocket method is defined on the view
+        if request.method == "GET" and request.environ.get("wsgi.websocket"):
+            ws_meth = getattr(self, "websocket", None)
+            if ws_meth is None:
+                abort(400, "Unable to upgrade websocket connection")
+            return ws_meth
+
+        return meth
+
     def dispatch_request(self, *args, **kwargs):
         """
 
         :param *args: 
         :param **kwargs: 
 
         """
-        meth = getattr(self, request.method.lower(), None)
-
-        # If the request method is HEAD and we don't have a handler for it
-        # retry with GET.
-        if meth is None and request.method == "HEAD":
-            meth = getattr(self, "get", None)
+        meth = self._find_request_method()
 
         # Generate basic response
         return self.represent_response(meth(*args, **kwargs))
@@ -272,7 +282,7 @@ def dispatch_request(self, *args, **kwargs):
         :param **kwargs: 
 
         """
-        meth = getattr(self, request.method.lower(), None)
+        meth = self._find_request_method()
 
         # Let base View handle non-POST requests
         if request.method != "POST":
@@ -414,12 +424,7 @@ def dispatch_request(self, *args, **kwargs):
         :param **kwargs: 
 
         """
-        meth = getattr(self, request.method.lower(), None)
-
-        # If the request method is HEAD and we don't have a handler for it
-        # retry with GET.
-        if meth is None and request.method == "HEAD":
-            meth = getattr(self, "get", None)
+        meth = self._find_request_method()
 
         # POST and PUT methods can be used to write properties
         # In all other cases, ignore arguments