1 files changed, 11 insertions, 5 deletions
diff --git a/modern/src/reducers/index.js b/modern/src/reducers/index.js
index ac592bfe..4593d1f3 100644
--- a/modern/src/reducers/index.js
+++ b/modern/src/reducers/index.js
@@ -1,20 +1,26 @@
 const initialState = {
-  devices: [],
-  positions: [],
-  events: []
+  devices: new Map(),
+  positions: new Map()
 };
 
+function updateMap(map, array, key) {
+  for (let value of array) {
+    map.set(value[key], value);
+  }
+  return map;
+}
+
 function rootReducer(state = initialState, action) {
   switch (action.type) {
     case 'UPDATE_DEVICES':
       return Object.assign({}, {
         ...state,
-        devices: [...action.devices]
+        devices: updateMap(state.devices, action.devices, 'id')
       });
     case 'UPDATE_POSITIONS':
       return Object.assign({}, {
         ...state,
-        positions: [...action.positions]
+        positions: updateMap(state.positions, action.positions, 'deviceId')
       });
     default:
       return state;