Update action_bucket column with new name and default value
<?php

use Illuminate\Support\Facades\Schema;
use Illuminate\Database\Schema\Blueprint;
use Illuminate\Database\Migrations\Migration;

class MakeBucketAndDetailsColumnsNullable extends Migration
{
    /**
     * Run the migrations.
     *
     * @return void
     */
    public function up()
    {
        Schema::table('posts', function (Blueprint $table) {
            $table->text('details')->nullable()->change();
            $table->dropColumn('action_bucket');
            $table->string('action')->index()->after('type')->default('default')->comment('Describes the bucket the action is tied to. A campaign could ask for multiple types of actions throught the life of the campaign.');
        });
    }

    /**
     * Reverse the migrations.
     *
     * @return void
     */
    public function down()
    {
        Schema::table('posts', function (Blueprint $table) {
            $table->text('details')->nullable(false)->change();
            $table->string('action_bucket')->index()->after('type')->comment('Describes the bucket the action is tied to. A campaign could ask for multiple types of actions throught the life of the campaign.');
            $table->dropColumn('action');
        });
    }
}

<?php

use Illuminate\Support\Facades\Schema;
use Illuminate\Database\Schema\Blueprint;
use Illuminate\Database\Migrations\Migration;

class MakeBucketAndDetailsColumnsNullable extends Migration
{
    /**
     * Run the migrations.
     *
     * @return void
     */
    public function up()
    {
        Schema::table('posts', function (Blueprint $table) {
            $table->string('action_bucket')->nullable()->change();
            $table->text('details')->nullable()->change();
        });
    }

    /**
     * Reverse the migrations.
     *
     * @return void
     */
    public function down()
    {
        Schema::table('posts', function (Blueprint $table) {
            $table->string('action_bucket')->nullable(false)->change();
            $table->text('details')->nullable(false)->change();
        });
    }
}
