v0.68.6

CHANGELOG.md

@@ -1,5 +1,9 @@
 # Change Log
 
+## 0.68.6
+
+- Fixed `applySnapshot` generating no-op patches sometimes.
+
 ## 0.68.5
 
 - Fixed `fromSnapshotProcessor` not accepting null or undefined when a `tProp` with a default value was used.

packages/lib/package.json

@@ -1,6 +1,6 @@
 {
   "name": "mobx-keystone",
-  "version": "0.68.5",
+  "version": "0.68.6",
   "description": "A MobX powered state management solution based on data trees with first class support for TypeScript, snapshots, patches and much more",
   "keywords": [
     "mobx",

packages/lib/src/snapshot/reconcileModelSnapshot.ts

@@ -5,6 +5,7 @@ import { isReservedModelKey, modelIdKey, modelTypeKey } from "../model/metadata"
 import { isModel, isModelSnapshot } from "../model/utils"
 import type { ModelClass } from "../modelShared/BaseModelShared"
 import { getModelInfoForName } from "../modelShared/modelInfo"
+import { deepEquals } from "../treeUtils/deepEquals"
 import { runTypeCheckingAfterChange } from "../tweaker/typeChecking"
 import { withoutTypeChecking } from "../tweaker/withoutTypeChecking"
 import { failure, isArray } from "../utils"
@@ -49,8 +50,11 @@ function reconcileModelSnapshot(
       return fromSnapshot<AnyModel>(sn)
     }
   } else if (isArray(parent)) {
-    // no id inside an array, no reconciliation possible
-    return fromSnapshot<AnyModel>(sn)
+    // no id and inside an array? no reconciliation possible,
+    // unless the snapshots are equivalent (note deep equals will use the snapshot of value auto)
+    if (!deepEquals(value, sn)) {
+      return fromSnapshot<AnyModel>(sn)
+    }
   }
 
   const modelObj: AnyModel = value

packages/lib/src/snapshot/reconcileSnapshot.ts

@@ -4,6 +4,7 @@ import { isModel } from "../model/utils"
 import { fastGetParentPathIncludingDataObjects } from "../parent"
 import { failure, isMap, isPrimitive, isSet } from "../utils"
 import type { ModelPool } from "../utils/ModelPool"
+import { getSnapshot } from "./getSnapshot"
 import { registerDefaultReconcilers } from "./registerDefaultReconcilers"
 
 type Reconciler = (value: any, sn: any, modelPool: ModelPool, parent: any) => any | undefined
@@ -26,6 +27,12 @@ export function reconcileSnapshot(value: any, sn: any, modelPool: ModelPool, par
     return sn
   }
 
+  // if the snapshot passed is exactly the same as the current one
+  // then it is already reconciled
+  if (getSnapshot(value) === sn) {
+    return value
+  }
+
   registerDefaultReconcilers()
 
   const reconcilersLen = reconcilers.length

packages/lib/test/ref/rootRef.test.ts

@@ -22,6 +22,8 @@ import {
   Ref,
   rootRef,
   runUnprotected,
+  tProp,
+  types,
   undoMiddleware,
 } from "../../src"
 import { autoDispose } from "../utils"
@@ -807,3 +809,34 @@ test("generic typings", () => {
   // @ts-expect-error
   genericRef2(new GenericModel({ v1: 1, v2: "2" }))
 })
+
+test("issue #456", () => {
+  @model("issue #456/Todo")
+  class Todo extends Model({
+    id: idProp,
+    text: tProp(types.string, ""),
+  }) {}
+
+  const todoRef = rootRef<Todo>("issue #456/TodoRef")
+
+  @model("issue #456/TodoList")
+  class TodoList extends Model({
+    todos: tProp(types.array(Todo)),
+    selectedRef: tProp(types.ref(todoRef)),
+    selectedRefs: tProp(types.array(types.ref(todoRef))),
+  }) {}
+
+  const todoList = new TodoList({
+    todos: [new Todo({ id: "todo1" })],
+    selectedRef: todoRef("todo1"),
+    selectedRefs: [todoRef("todo1")],
+  })
+
+  const patches: Patch[][] = []
+
+  onPatches(todoList, (p) => patches.push(p))
+  const sn = getSnapshot(todoList)
+  applySnapshot(todoList, sn)
+
+  expect(patches).toHaveLength(0)
+})

packages/lib/test/snapshot/snapshot.test.ts

@@ -568,7 +568,7 @@ test("id-less reconciliation", () => {
   let id = 0
 
   @model("idlr/i")
-  class I extends Model({}) {
+  class I extends Model({ x: prop(0) }) {
     id = id++
   }
 
@@ -590,15 +590,16 @@ test("id-less reconciliation", () => {
   applySnapshot(
     r,
     modelSnapshotOutWithMetadata(R, {
-      arr: [modelSnapshotOutWithMetadata(I, {}), modelSnapshotOutWithMetadata(I, {})],
-      m: modelSnapshotOutWithMetadata(I, {}),
+      arr: [modelSnapshotOutWithMetadata(I, { x: 0 }), modelSnapshotOutWithMetadata(I, { x: 1 })],
+      m: modelSnapshotOutWithMetadata(I, { x: 0 }),
     })
   )
 
   expect(r.m.id).toBe(2)
-  // no reconciliation inside an array
-  expect(r.arr[0].id).toBe(3)
-  expect(r.arr[1].id).toBe(4)
+  expect(r.arr[0].id).toBe(0)
+  // no reconciliation inside an array if data is different
+  // (in this case x is 1)
+  expect(r.arr[1].id).toBe(3)
 })
 
 test("id-full reconciliation", () => {