publishable/database/migrations/2017_04_11_000000_alter_post_nullable_fields_table.php
public function down()
    {
        Schema::table('posts', function (Blueprint $table) {
            $table->text('excerpt')->change();
            $table->text('meta_description')->change();
            $table->text('meta_keywords')->change();
        });
    }
public function down()
    {
        Schema::table('posts', function (Blueprint $table) {
            $table->text('excerpt')->change();
            $table->text('meta_description')->change();
            $table->text('meta_keywords')->change();
        });
    }
Reverse the migrations.

@return void