Improve streaming logic

awesome-reactivesearch · Feb 17, 2018 · 13ed7b7 · 13ed7b7
1 parent d495ae3
commit 13ed7b7
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Showing 2 changed files with 16 additions and 41 deletions.
diff --git a/components/TodoItem.js b/components/TodoItem.js
@@ -68,7 +68,10 @@ class TodoItem extends Component {
               flexDirection: 'row',
             }}
           >
-            <CheckBox checked={todo.completed} />
+            <CheckBox
+              checked={todo.completed}
+              onPress={() => this.onTodoItemToggle(todo, onUpdate)}
+            />
             <Body
               style={{
                 flex: 1,

diff --git a/utils/index.js b/utils/index.js
@@ -1,46 +1,18 @@
 class Utils {
-  // [source] https://gist.github.com/lmfresneda/9158e06a93a819a78b30cc175573a8d3
-  static removeDuplicates = (arr, prop) => {
-    const obj = {};
-    for (let i = 0, len = arr.length; i < len; i++) {
-      if (!obj[arr[i][prop]]) obj[arr[i][prop]] = arr[i];
-    }
-    const newArr = [];
-    for (const key in obj) newArr.push(obj[key]); // eslint-disable-line
-    return newArr;
-  };
-
   static mergeTodos(todos, streamData) {
-    // note: don't judge for the logic
-    let todosData = todos;
-    if (todosData.length > 0 || streamData.length > 0) {
-      todosData = todosData.map((todo) => {
-        let todoToReturn = todo;
-        for (let i = 0; i < streamData.length; i++) {
-          // variable to track untouched todos after checking with all todosData iems
-          streamData[i].touched = false; // eslint-disable-line
-          // [case]: todo data is updated
-          if (todo._id === streamData[i]._id) {
-            todoToReturn = streamData[i];
-            streamData[i].touched = true; // eslint-disable-line
-          }
-        }
-        return todoToReturn;
-      });
-      // [case]: new todo is added
-      // collect untouched todos || the newly added streamed todos
-      const newTodos = streamData.filter(todo => !todo.touched);
-      // merge the new streaming data with updated streaming data
-      if (newTodos.length > 0) todosData = todosData.concat(newTodos);
-      // clean unpredictable duplicates
-      todosData = this.removeDuplicates(todosData, '_id');
-      // clean deleted todos
-      todosData = todosData.filter(todo => !todo._deleted);
-    }
-    // sorting todos based on creation time
-    todosData = todosData.sort((a, b) => a.createdAt - b.createdAt);
+    // generate an array of ids of streamData
+    const streamDataIds = streamData.map(todo => todo._id);
 
-    return todosData;
+    return todos
+      // consider streamData as the source of truth
+      // first take existing todos which are not present in stream data
+      .filter(({ _id }) => !streamDataIds.includes(_id))
+      // then add todos from stream data
+      .concat(streamData)
+      // remove todos which are deleted in stream data
+      .filter(todo => !todo._deleted)
+      // finally sort on the basis of creation timestamp
+      .sort((a, b) => a.createdAt - b.createdAt);
   }
 }