This patch-level release fixes an issue with snapshots being preprocessed twice in some instances. Thanks to @adamkovalsky for the PR (#1822)!

• Fixes a regression introduced in https://github.com/mobxjs/mobx-state-tree/pull/1792 where a snapshot preprocessor gets called on an already preprocessed snapshot, resulting in potential errors.

If there are any problems with this release, please file an issue or leave comments in the attached Discussion! Thanks to everyone who contributed!

This patch-level release fixes three issues with node reconciliation. Thanks to @adamkovalsky for the PR!

• Adds a getReconcilationType method to BaseNode, which returns the type which should be used for reconcilating the node. This is normally the node's type, but in the case of snapshotProcessor it is overridden to be the snapshotProcessor type. This is necessary so that the union type reconcile can correctly reconcile the "current" node first if it's possible. This fixes #1791.
• Fixes the snapshotProcessor type's isValidSnapshot and is methods to return a validation error and not to throw if the specified preprocessor fails, which can happen when checking if an arbitrary snapshot is valid input (e.g. when determining a union type). We can't expect preprocessors to accept any arbitrary input, so we must assume they can throw when provided with invalid snapshots. This also fixes #1777.
• Fixes the array's areSame utility to first check that the provided value is a valid snapshot before calling isMatchingSnapshotId, to avoid the preprocessor throwing an error if the provided snapshot is invalid.

If there are any problems with this release, please file an issue or leave comments in the attached Discussion! Thanks to everyone who contributed!

This patch-level release has a few small updates:

• Removed a couple MobX TypeScript properties that have already been removed in MobX in #1666 by @Strandinator
• Fixes array reconciliation in snapshotProcessor in #1784 by @adamkovalsky, fixing #1776
• Updates devDependencies across the project in #1786 by @jamonholmgren
• Some documentation updates as well

If there are any problems with this release, please file an issue or leave comments in the attached Discussion! Thanks to everyone who contributed!

This patch-level release fixes #1702, "MST should work with useProxies: ifAvailable option from mobx." It should be fully backwards-compatible with previous 5.x releases.

MobX 6.0 was released recently and ifAvailable was broken in MST. This PR fixes that.

Thanks to @BATCOH for reporting the issue and the PR fixing it!

This release fixes #1653 (PR #1656). MobX 6.1.0 introduced a new issue and this addresses that. Thanks to @urugator!

There should be no breaking changes.

This new approach, replacing makeObservable with manually created actions and computed views, also seems to have improved instance instantiation speed (MyModel.create()) by about 20% in @jamonholmgren's benchmarks.

Please report any new bugs and we will address as soon as possible. We wanted to get this fix into the hands of users ASAP as previously doing yarn add mobx mobx-state-tree means you would end up with brokenness.

What's New

Version 5.0.0 includes bugfixes that may in rare cases cause breaking changes if relying on undocumented behavior. Most apps should be able to upgrade without problems. Please file an issue if you upgrade and it causes any new bugs.

Bugfixes

• isPlainObject() supports objects from another window (#1584 by @ConneXNL)
• Models from snapshot processors can now be added to maps (#1581 by @kidroca)
• applyPatch can now replace root of store if path is empty (#1522 by @epodgaetskiy)

Bug Fixes

• Add missing type definitions for onInvalidated in safeReference -- #1610 by @getkey

Version 4

(This version is tagged 4.0.2, but is the first release in the v4 major version.)

BREAKING CHANGE

MobX 6 is now supported! This version of MobX replaces MobX 4 and MobX 5, and works in environments that support Proxy as well as those that don't. In the past, MobX 4 was for environments without Proxy, and MobX 5 was for those which supported Proxy. MobX 6 works in both.

Note that MobX-State-Tree v4 will only work with MobX 6, so if you need to stay on MobX 4 or 5, you'll need to also stay on MST 3.

New Maintainer

@jamonholmgren is now taking over as lead maintainer. Stay tuned for more announcements and an updated roadmap.