Merge pull request #969 from streamich/diff-obj-key

Ability to shallow merge "obj" node keys

Author: streamich

packages/json-joy/src/json-crdt-diff/JsonCrdtDiff.ts

@@ -248,6 +248,31 @@ export class JsonCrdtDiff {
     return this.builder.flush();
   }
 
+  /** Diffs only keys present in the destination object. */
+  public diffDstKeys(src: ObjNode, dst: Record<string, unknown>): Patch {
+    const builder = this.builder;
+    const inserts: [key: string, value: ITimestampStruct][] = [];
+    const keys: string[] = Object.keys(dst);
+    const keyLength = keys.length;
+    for (let i = 0; i < keyLength; i++) {
+      const key = keys[i];
+      const child = src.get(key);
+      const dstValue = dst[key];
+      if (!child) {
+        inserts.push([key, this.buildConView(dstValue)]);
+        continue;
+      }
+      try {
+        this.diffAny(child, dstValue);
+      } catch (error) {
+        if (error instanceof DiffError) inserts.push([key, this.buildConView(dstValue)]);
+        else throw error;
+      }
+    }
+    if (inserts.length) builder.insObj(src.id, inserts);
+    return this.builder.flush();
+  }
+
   protected buildView(dst: unknown): ITimestampStruct {
     const builder = this.builder;
     if (dst instanceof Timestamp) return builder.con(dst);

packages/json-joy/src/json-crdt-diff/index.ts

@@ -10,6 +10,6 @@ export const diff = (src: NodeApi<any>, dst: unknown): Patch | undefined => {
 
 export const merge = (src: NodeApi<any>, dst: unknown): Patch | undefined => {
   const patch = diff(src, dst);
-  if (patch) src.api.model.applyPatch(patch);
+  if (patch) src.api.model.applyLocalPatch(patch);
   return patch;
 };

packages/json-joy/src/json-crdt/model/api/__tests__/ObjApi.spec.ts

@@ -0,0 +1,49 @@
+import {Model} from '../../Model';
+
+describe('merge', () => {
+  test('can subscribe and un-subscribe to "view" events', async () => {
+    const doc = Model.create({
+      obj: {
+        foo: new Uint8Array([1, 2, 3]),
+        bar: '123',
+      },
+    });
+    const api = doc.api;
+    const obj = api.obj(['obj']);
+    obj.merge({
+      foo: new Uint8Array([4, 5, 6]),
+      baz: 'new',
+    });
+    expect(obj.view()).toEqual({
+      foo: new Uint8Array([4, 5, 6]),
+      baz: 'new',
+    });
+  });
+
+  test('can merge specific key', async () => {
+    const doc = Model.create({
+      obj: {
+        foo: new Uint8Array([1, 2, 3]),
+        bar: '123',
+      },
+    });
+    const api = doc.api;
+    const obj = api.obj(['obj']);
+    obj.get('foo').merge(new Uint8Array([4, 5, 6]));
+    expect(obj.view()).toEqual({
+      foo: new Uint8Array([4, 5, 6]),
+      bar: '123',
+    });
+    obj.mergeKeys({foo: {aha: 123}});
+    expect(obj.view()).toEqual({
+      foo: {aha: 123},
+      bar: '123',
+    });
+    obj.mergeKeys({foo: '123', x: 'y', bar: '1234'});
+    expect(obj.view()).toEqual({
+      foo: '123',
+      bar: '1234',
+      x: 'y',
+    });
+  });
+});

packages/json-joy/src/json-crdt/model/api/nodes.ts

@@ -10,6 +10,7 @@ import {PatchBuilder} from '../../../json-crdt-patch/PatchBuilder';
 import {MergeFanOut, MicrotaskBufferFanOut} from './fanout';
 import {ExtNode} from '../../extensions/ExtNode';
 import * as diff from '../../../json-crdt-diff';
+import {JsonCrdtDiff} from '../../../json-crdt-diff/JsonCrdtDiff';
 import type {Path} from '@jsonjoy.com/json-pointer';
 import type {Extension} from '../../extensions/Extension';
 import type {ExtApi} from '../../extensions/types';
@@ -540,6 +541,20 @@ export class ObjApi<N extends ObjNode<any> = ObjNode<any>> extends NodeApi<N> {
     return this.node.keys.has(key);
   }
 
+  /** Diffs only keys present in `dst` object. */
+  diffKeys(dst: Record<string, unknown>): Patch | undefined {
+    const diff = new JsonCrdtDiff(this.api.model);
+    const patch = diff.diffDstKeys(this.node, dst);
+    return patch.ops.length ? patch : void 0;
+  }
+
+  /** Merges only keys present in `dst` object. */
+  mergeKeys(dst: Record<string, unknown>): Patch | undefined {
+    const patch = this.diffKeys(dst);
+    if (patch) this.api.model.applyLocalPatch(patch);
+    return patch;
+  }
+
   /**
    * Returns a proxy object for this node. Allows to access object properties
    * by key.