Add reverse

dash/_patch.py

@@ -107,6 +107,9 @@ def insert(self, index, item):
     def clear(self):
         self._operations.append(_operation("Clear", self._location))
 
+    def reverse(self):
+        self._operations.append(_operation("Reverse", self._location))
+
     def extend(self, item):
         if not isinstance(item, (list, tuple)):
             raise TypeError(f"{item} should be a list or tuple")

dash/dash-renderer/src/actions/patch.ts

@@ -8,7 +8,8 @@ import {
     insert,
     is,
     path,
-    prepend
+    prepend,
+    reverse
 } from 'ramda';
 
 type PatchOperation = {
@@ -132,6 +133,10 @@ const patchHandlers: {[k: string]: PatchHandler} = {
     Clear: (previous, patchOperation) => {
         const prev: any = path(patchOperation.location, previous);
         return assocPath(patchOperation.location, empty(prev), previous);
+    },
+    Reverse: (previous, patchOperation) => {
+        const prev: any = path(patchOperation.location, previous);
+        return assocPath(patchOperation.location, reverse(prev), previous);
     }
 };
 

tests/integration/test_patch.py

@@ -51,6 +51,7 @@ def test_pch001_patch_operations(dash_duo):
             html.Button("Delete", id="delete-btn"),
             html.Button("Delete index", id="delete-index"),
             html.Button("Clear", id="clear-btn"),
+            html.Button("Reverse", id="reverse-btn"),
             dcc.Store(
                 data={
                     "value": "unset",
@@ -181,6 +182,17 @@ def on_clear(_):
 
         return p
 
+    @app.callback(
+        Output("store", "data", allow_duplicate=True),
+        Input("reverse-btn", "n_clicks"),
+        prevent_initial_call=True,
+    )
+    def on_reverse(_):
+        p = Patch()
+        p.array.reverse()
+
+        return p
+
     dash_duo.start_server(app)
 
     assert dash_duo.get_logs() == []
@@ -263,6 +275,14 @@ def get_output():
         "Extend",
     ]
 
+    dash_duo.find_element("#reverse-btn").click()
+    assert get_output().get("array") == [
+        "Extend",
+        "Append",
+        "initial",
+        "Prepend",
+    ]
+
     dash_duo.find_element("#clear-btn").click()
     assert get_output()["array"] == []
 

tests/unit/test_patch.py

@@ -220,3 +220,15 @@ def test_pat017_patch_clear():
     p.clear()
     data = patch_to_dict(p)
     assert data["operations"][0] == {"operation": "Clear", "location": [], "params": {}}
+
+
+def test_pat018_patch_reverse():
+    p = Patch()
+
+    p.reverse()
+    data = patch_to_dict(p)
+    assert data["operations"][0] == {
+        "operation": "Reverse",
+        "location": [],
+        "params": {},
+    }