[5.5] Ensure Pivot models $dateFormat is used when creating a pivot record.

[kevinruscoe]

As with #22484 , when inserting a pivot record via ->attach() the InteractsWithPivotTable.php trait doesn't check to see if the pivot table has a model representation. It' simply finds the table name and inserts a new record. Because of this, the timestamps are passed as Carbon instances and then turn to strings via its toString() method. If the consumer is using a pivot Model, it should use that models dateFormat to format by, not the toString() method. This simply news-up the pivot model, fetches it's dateformat and formats the $fresh date against it.

[kevinruscoe]

...actually, hold fire with this.

[kevinruscoe]

This won't actually fix the issue above, it does fix some sort of issue ;), in that the ->attach() method now actually adheres to what the Pivot model requests the $dateFormat to be.

[taylorotwell]

So it doesn't fix the issue you link? Need more information and explanation before merging.

[kevinruscoe]

It's fixes part of the issue above, but the actual issue it fixes is as follows.

When using the ->attach() to relate many-to-many records, the trait doesn't check to see how the date should be stored. It simply find's the pivot table, checks if the timestamps are needed and then spins up 2 Carbon instances for the created_at and updated_at. When inserting these records into the DB the Carbon instances are cast as strings, so the toString() method is called and it converts them to Carbon's default (Y-m-d h:i:s).

This PR basically checks to see if the Pivot model has a $dateFormat specified, if it does it'll use them when adding the record to the DB, rather than the default toString() method.

[sisve]

This sounds like something that should have tests.

[taylorotwell]

@sisve indeed.

[taylorotwell]

@kevdotbadger You are calling ::getDateFormat() but I see no static method getDateFormat on any model class at all? Have you actually run this code?

[taylorotwell]

I put this in 5.6 since it required a breaking change to method visibility of getDateFormat. I also added a test.

[brlocky]

I'm having this issue in Laravel 9 !
So basically when using the attach to store a relation, the datetime precision is not respected.
2022-08-24 23:21:39.000000

I have precision 6 on the timestamps and also the option ->withTimestamps();

[brlocky]

the issue seams to be fixed by adding the .u on the default time format, with a patch on Grammar.php

namespace Illuminate\Database;

     * Get the format for database stored dates.
     *
     * @return string
     */
    public function getDateFormat()
    {
        return 'Y-m-d H:i:s.u';
    }
    ```