MODULE creation and YII migrations

[Chadduck]

Apologies in advance for the complexity and being long-winded with this topic...  I am looking for input BEFORE I make a mistake.  Hopefully @pandrei you will give me the answers and insight I need.

After completing the tutorial posted by Yuriy Nechitajlo in the Wiki entitled "Creating Extension from Scratch" I have began to transition a module from OSC Frozen to Osc V4.  I am at a point where I need some insight about using the YII database migration functions within the module as part of the Setup.php file.

Yes, I have made a backup of the database...

PART 1 of my question(s)

I need to add two columns to an existing table.  Realizing how dangerous it can be for the novice to attempt this I would like to make absolutely certain that I understand the CORRECT way to do this.  Using the YII v2 documentation located here
https://www.yiiframework.com/doc/guide/2.0/en/db-migrations

It appears that these are the necessary commands... 

Quote

class m150811_220037_add_position_column_to_post_table extends Migration
{
    public function up ()
    {
        $this->addColumn('post', 'position', $this->integer()); 
    }

public function down ()
    {
        $this->dropColumn('post', 'position'); 
    }
}

As I understand it the above would add the column called "Position" to the tablle called "Post".  It is also my understanding that the $this portion would be similar to  

$this->addColumn('post', 'postion', $this->string(64));

PART 2 of my question(s)

Regarding - this particular line of the YII 2 example

m150811_220037_add_position_column_to_post_table extends Migration

Does the "add_position_column_to_post_table" need to reflect the CORRECT info like this

add_ <DB COLUMN NAME> _column_to_ <DB TABLE NAME> _table

OR is the only required part the "m150811_220037"?

I couldn't locate an example to follow and the Tutorial doesn't cover it.

PART 3 of my question(s)

During the extension installation phase does migration run automatically OR is that done in the Settings > Cache control section with Migrations Apply checked then pressing Flush button afterward?

Hopefully this makes sense because I really don't want to make a mistake.

BJ

[pandrei]

13 hours ago, Chadduck said:

Apologies in advance for the complexity and being long-winded with this topic...  I am looking for input BEFORE I make a mistake.  Hopefully @pandrei you will give me the answers and insight I need.

Migrations are used to modify core of osCommerce. If you are working on extension, you don't need to use it. osCommerce has its own extension methodology.

I think this sample is an answer to your questions: https://www.oscommerce.com/wiki/Sample_of_Creating_Extensions_with_Widget_for_Editing_and_Outputting_Additional_Information_about_Product

[Chadduck]

@pandrei

Thank you.  I had pulled that file but did not realize it was a tutorial that included changing the database by adding a field to an existing table. 

Will step my way through it and learn things that I don't know.

Thank you again for pointing me in the correct direction.

BJ