feat!: use mongodb function to check for dirtiness

[divine]

This is rework of test for PR #1990

To check if a field is dirty we can simply use fromPHP() function of the mongodb driver. Besides, we shouldn't use the SQL-specific logic of Illuminate\Eloquent\Model::originalIsEquivalent() for mongodb. In sql, fields keep their schema data types and changing integer 1 to string '1' actually does nothing. However, in mongodb fields accept their types as they are inserted/updated. Therefore, if we change value of a field from (int)1 to (string)'1' we actually must regard it as dirty. This change is backward incompatible. Don't know if anyone likes the current behaviour more.

[codecov-commenter]

Codecov Report

Patch coverage: 100.00% and project coverage change: +0.07% 🎉

Comparison is base (e652b0c) 90.64% compared to head (2a2bb47) 90.72%.

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Additional details and impacted files

@@             Coverage Diff              @@
##             master    #2515      +/-   ##
============================================
+ Coverage     90.64%   90.72%   +0.07%     
+ Complexity      758      754       -4     
============================================
  Files            34       34              
  Lines          1849     1843       -6     
============================================
- Hits           1676     1672       -4     
+ Misses          173      171       -2     

Files Changed	Coverage Δ
src/Eloquent/Model.php	90.90% <100.00%> (+0.75%)	⬆️

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[GromNaN]

This change will leverage the MongoDB driver to detect attribute changes. It will reduce bugs and make the maintenance easier.
Could you rebase onto master and add a changelog entry?

[divine]

This change will leverage the MongoDB driver to detect attribute changes. It will reduce bugs and make the maintenance easier. Could you rebase onto master and add a changelog entry?

Hello,

Done! Can you please review it?

Thanks!

[GromNaN]

LGTM.

[alcaeus]

A couple of notes on this:

• fromPHP will be deprecated and is replaced by Document::fromPHP
• Root-Level encoding is only supported for documents (i.e. any object or array with string keys)
• If $attribute happens to be an object (e.g. an embedded document), this conversion will not yield the correct results as only public properties are encoded, which is most likely wrong for any Model
• This may not be an issue, but I'll note that using this comparison ['foo' => 'bar', 'bar' => 'foo'] and ['bar' => 'foo', 'foo' => 'bar'] will not be treated as equal. That said, we don't have a good way to check BSON equality, and one may argue that two BSON documents with the same key/value pairs in different order shouldn't be considered equal.

For the time being, using this comparison may be feasible as long as we can ensure that it doesn't have side effects for embedded documents.

[alcaeus]

Please add a test using embedded documents and arrays to ensure correct behaviour.

[GromNaN]

Now that some transformations have been moved to the query builder (DateTimeInterface <=> UTCDateTime in #3119 and #3105), we might adjust to convert all dates before comparison.