Column altering in migration may not apply

[hovsep]

I have a text column called "body" . Then I want to alter it to be longText, so I run a migration with

$table->longText('body')->change(); (of course I have doctrine/dbal in my composer.json)

So migration runs ok, but actually no modification occurs.

I make some investigation and found that Laravel uses Doctrine\DBAL\Schema\Comparator class to make diffTable. Ok, sounds good, but how it compares columns? I debugged column properties at diffColumn method and see that my "longText" become to Doctrine\DBAL\Types\TextType.

So Doctrine makes no difference between Text and LongText. It is not ok.

[EliasZ]

Doctrine can make a difference between the various text sizes. See mapping matrix.

For example. LONGTEXT will be used if

column length is less or equal to 2 ^ 32 - 1 = 4294967295 or empty

If your issue is valid, there must be something wrong with calculateDoctrineTextLength. Maybe you can try and validate that.

[hovsep]

I investigated deeper and found a problem in vendor/doctrine/dbal/lib/Doctrine/DBAL/Schema/MySqlSchemaManager.php _getPortableTableColumnDefinition method.

For example I create a migration with single mutation ($table->text('body')->change();)

So i debug $tableColumn var at beginning of the method :

Array ( [Field] => body [Type] => longtext [Null] => NO [Key] => [Default] => [Extra] => [Comment] => [CharacterSet] => utf8 [Collation] => utf8_unicode_ci )

Then I debug result :
`Doctrine\DBAL\Schema\Column Object
(
[_type:protected] => Doctrine\DBAL\Types\TextType Object
(
)

[_length:protected] => 
[_precision:protected] => 10
[_scale:protected] => 0
[_unsigned:protected] => 
[_fixed:protected] => 
[_notnull:protected] => 1
[_default:protected] => 
[_autoincrement:protected] => 
[_platformOptions:protected] => Array
    (
        [collation] => utf8_unicode_ci
    )

[_columnDefinition:protected] => 
[_comment:protected] => 
[_customSchemaOptions:protected] => Array
    (
    )

[_name:protected] => body
[_namespace:protected] => 
[_quoted:protected] => 

)
`

As you can see original longtext became a portable text type. So table diff will not be detected. I think such a behaviour may be useful when same code should work with different databases, but it is bug when we make a migration.

[EliasZ]

You should file your findings over at https://github.com/doctrine/dbal/issues/new 😃

This isn't an issue with Laravel. Laravel uses doctrine/dbal for certain database mutations.