How can I remove a unique constraint on a field when performing a down migration?

How can I remove a unique constraint on a field when performing a down migration? - Printable Version

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How can I remove a unique constraint on a field when performing a down migration? - SteeveDroz - 12-02-2020

Copy-pasted from https://stackoverflow.com/questions/65039833/how-can-i-remove-a-unique-constraint-on-a-field-when-performing-a-down-migration, feel free to answer the question there too to win a few points.

I have to add a unique constraint to a field after the table was created. I therefore set up a migration file with this in the up() method:

Code:
$fields = [

    'slug' => [

        'type' => 'varchar',

        'constraint' => 255,

        'unique' => true

    ]

];

$this->forge->modifyColumn('pages', $fields);

And in down():

Code:
$fields = [

    'slug' => [

        'type' => 'varchar',

        'constraint' => 255,

        'unique' => false

    ]

];

$this->forge->modifyColumn('pages', $fields);

This doesn't work.

When calling

Code:
php spark migrate:rollback

, the migration is correctly un-applied ("migrations" table is modified) but the fields stay unique.
What should I put in down() instead?

RE: How can I remove a unique constraint on a field when performing a down migration? - InsiteFX - 12-02-2020

I don't think that you can without deleting the field and adding it in again

RE: How can I remove a unique constraint on a field when performing a down migration? - daveontheciforum - 12-12-2020

You could execute some SQL to delete it directly:

PHP Code:
public function down()
{  
    $this->db->simpleQuery("ALTER TABLE pages DROP INDEX slug");
} 

(the unique index will have a name - if you don't know what it is, you can get it with this: SHOW INDEX FROM pages Wink