UNSET event in forest

packages/forest/__tests__/forest.spec.ts

@@ -260,3 +260,38 @@ test("hard patch with selector replaces selected state", () => {
     compTree!.nodes["comp1"]!.state["breakpoints"]["991"]["styles"]["height"]
   ).toBe("20px");
 });
+
+test("unset event", () => {
+  const forest = createForest(forestDef);
+  const compTree = forest.tree(componentTreeDef.modulePath);
+  forest.handleEvents({
+    name: "TEST_EVENTS",
+    events: [
+      {
+        type: `CREATE$$${componentTreeDef.modulePath}`,
+        id: "comp1",
+        meta: {},
+        state: {
+          parent: { id: "body", index: 0 },
+        },
+      },
+      {
+        type: `PATCH$$${componentTreeDef.modulePath}`,
+        id: "comp1",
+        slice: {
+          alias: "comp1Alias",
+        },
+      },
+      {
+        type: `UNSET$$${componentTreeDef.modulePath}`,
+        id: "comp1",
+        selector: ["parent", "id"],
+      },
+    ],
+    meta: { agent: "server-sent" },
+  });
+  expect(compTree?.nodes).toBeDefined();
+  expect(compTree!.nodes["comp1"]!.state).toHaveProperty("parent");
+  expect(compTree!.nodes["comp1"]!.state.parent).toHaveProperty("index");
+  expect(compTree!.nodes["comp1"]!.state.parent).not.toHaveProperty("id");
+});

packages/forest/src/forest.ts

@@ -15,6 +15,7 @@ import {
   TreeNode,
   HardPatchEvent,
   TreeDef,
+  UnsetEvent,
 } from "./types";
 
 function mergeStateCustomizer(obj: any, src: any) {
@@ -318,6 +319,31 @@ export function createForest(def: { trees: TreeDef[] }): Forest {
         });
       }
     }
+    if (event.type.startsWith("UNSET")) {
+      const unsetEvent = event as UnsetEvent;
+      const treeId = unsetEvent.type.slice("UNSET$$".length);
+      const tree = treeMap[treeId]!;
+      const selector = unsetEvent.selector;
+      // store old state
+      const oldState = JSON.parse(
+        JSON.stringify(tree.nodes[unsetEvent.id]!.state)
+      );
+      let curr = tree.nodes[unsetEvent.id]!.state;
+      for (let i = 0; i < selector.length; i++) {
+        if (i === selector.length - 1) {
+          delete curr[selector[i]!];
+          break;
+        }
+        curr = curr[selector[i]!];
+      }
+      // emit change event
+      forestUpdateSubscribers.forEach((cb) => {
+        cb(
+          { type: "change", id: unsetEvent.id, treeId, oldState },
+          { name, meta }
+        );
+      });
+    }
   }
 
   function handleEvents(data: {

packages/forest/src/types.ts

@@ -77,13 +77,19 @@ export type HardPatchEvent = {
   selector?: string[];
 } & EventDto;
 
+export type UnsetEvent = {
+  id: string;
+  selector: string[];
+} & EventDto;
+
 export type AnyEvent =
   | CreateEvent
   | PatchEvent
   | DeleteEvent
   | LinkEvent
   | UnlinkEvent
-  | HardPatchEvent;
+  | HardPatchEvent
+  | UnsetEvent;
 
 export type TreeDefReturnType = {
   validateCreate: (event: CreateEvent) => boolean;