xaviergonz / mobx-keystone

Does computedTree support an array of models?
I get an error "an object cannot be assigned a new parent when it already has one" when the tree is updated for the second time.
https://codesandbox.io/s/mobx-keystone-computedtree-cscdc

@sisp

Already checking. I've been able to reproduce the error with this extension of the tests:

--- a/packages/lib/test/computedTree/computedTree.test.ts
+++ b/packages/lib/test/computedTree/computedTree.test.ts
@@ -73,6 +73,14 @@ class R extends Model({
     return ["abc"]
   }
 
+  @computedTree
+  get arrayOfModels() {
+    return [
+      new M({ id: `${this.id}.model1`, value: this.value }),
+      new M({ id: `${this.id}.model2`, value: this.value }),
+    ]
+  }
+
   @computedTree
   get plainObject() {
     return { key: "value" }
@@ -481,3 +489,9 @@ test("computed tree is readonly", () => {
     "tried to invoke action 'setValue' over a readonly node"
   )
 })
+
+test("computed tree works with an array of models", () => {
+  const r = new R({})
+  r.setValue(10)
+  expect(r.arrayOfModels.map((m) => m.value)).toEqual([10, 10])
+})

But I'm not sure yet why the error is happening.

@xaviergonz Do you think

mobx-keystone/packages/lib/src/computedTree/computedTree.ts

Lines 78 to 79 in e35a792

    
           tweak(oldValue, undefined) 
        
           tryUntweak(oldValue)

is correct or should entry.tweakedValue be untweaked as well somehow? I've been trying to debug it already but without success so far.

The error is occurring when this line is executed:

mobx-keystone/packages/lib/src/computedTree/computedTree.ts

Line 78 in e35a792

tweak(oldValue, undefined)

This fixes the new test:

--- a/packages/lib/src/computedTree/computedTree.ts
+++ b/packages/lib/src/computedTree/computedTree.ts
@@ -75,8 +75,9 @@ export function computedTree(
       return entry.tweakedValue
     }
 
-    tweak(oldValue, undefined)
-    tryUntweak(oldValue)
+    const oldTweakedValue = entry.tweakedValue
+    tweak(oldTweakedValue, undefined)
+    tryUntweak(oldTweakedValue)
 
     const tweakedValue = tweakComputedTreeNode(newValue, this, propertyKey)
     entry.value = newValue

But the getChildrenObjects and walkTree tests are failing then. 🤔

My bad, those tests need to be adapted.

I'll submit a PR with a fix later today.

Fixed in v1.1.1. Thanks!

Array of models in computedTree