[10.x] Allow specifying index name when calling ForeignIdColumnDefinition@constrained()

[cosmastech]

Problem

I prefer verbose naming. I have a migration that looks like this:

use App\Models\KnowledgeBaseResource;
use Illuminate\Database\Migrations\Migration;
use Illuminate\Database\Schema\Blueprint;
use Illuminate\Support\Facades\Schema;


return new class extends Migration
{
    public function up(): void
    {
        Schema::create('company_knowledge_base_resource_matches', function (Blueprint $table) {
            $table->id();
            $table->foreignIdFor(KnowledgeBaseResource::class)->nullable()->constrained()->nullOnDelete();
            $table->timestamps();
        });
    }
}

Which blows up:

SQLSTATE[42000]: Syntax error or access violation: 1059 Identifier name 'company_knowledge_base_resource_matches_knowledge_resource_id_foreign' is too long (Connection: mysql, SQL: alter table `company_knowledge_base_resource_matches` add constraint `company_knowledge_base_resource_matches_knowledge_resource_id_foreign` foreign key (`knowledge_base_resource_id`) references `knowledge_base_resources` (`id`) on delete set null)

This can be worked around, but doesn't allow the developer to use the nice features of the schema builder, puts a lot more of a lift on developers, and leaves more room for error.

Schema::create('company_knowledge_base_resource_matches', function (Blueprint $table) {
    $table->id();
    $table->foreignIdFor(KnowledgeBaseResource::class)->nullable();
    $table->timestamps();
    
    $table->foreign('knowledge_base_resource_id', 'my_foreign_index')->references('id')->on('knowledge_base_resources')->constrained()->nullOnDelete();
});

Solution

Allow calling code to specify the index name within the call to ForeignIdColumnDefinition@constrained().

This should not break backwards compatibility.

I also changed the second parameter of constrained() so that it allows null to be passed, which will coalesce to 'id'. I think this improves developer experience, so, a developer might write this instead:

Schema::create('company_knowledge_base_resource_matches', function (Blueprint $table) {
    $table->id();
    $table->foreignIdFor(KnowledgeBaseResource::class)
        ->nullable()
        ->constrained(null, null, 'my_foreign_index')
        ->nullOnDelete();
    $table->timestamps();
});

instead of: $table->foreignIdFor(SomeModel::class)->constrained(null, 'id', 'my_foreign_index')