[Proposal] Add schema method `storedAsNotNull` and `virtualAsNotNull`

[mpyw]

Currently ->storedAs() and ->virtualAs() always make them nullable.

https://github.com/laravel/framework/blob/1cbb54e9da52d66bc09e181c34520df283bf46cd/src/Illuminate/Database/Schema/Grammars/MySqlGrammar.php#L892-L897

But making generated columns non-nullable provides robust and flexible constraints.

Example

Goals

• We have members table and plans table
  • members.role takes one of owner guest subscriber
  • members.plan_id has value only when members.role is subscriber
• We also need to sort members in owner guest subscriber order.

Code

$table
->unsignedTinyInteger('sort_priority')
->storedAsNotNull("
    CASE WHEN role = 'owner' AND plan_id IS NULL THEN 1
         WHEN role = 'guest' AND plan_id IS NULL THEN 2
         WHEN role = 'subscriber' AND plan_id IS NOT NULL THEN 3
         ELSE NULL
    END
")
->index();

members.sort_priority allows us making fast sorting ORDER BY sort_priority, id ensuring strong consistency.

[mpyw]

Options:

• Backward Compatible: Add storedAsNotNull and virtualAsNotNull
• Breaking Change: Make storedAs and virtualAs not null by default and accept nullable call

[driesvints]

A pr for this was merged.