How to change eav_attribute table's note column's datatype varchar to mediumtext using declarative schema?

Question

I have follow this documnet https://devdocs.magento.com/guides/v2.3/extension-dev-guide/declarative-schema/db-schema.html but not get success

module.xml

        <?xml version="1.0"?>
        <!--
        /**
         * Copyright © Krish TechnoLabs, All rights reserved.
         */
        -->
        <config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:Module/etc/module.xsd">
            <module name="Ktpl_Test1" setup_version="1.0.0">
                <sequence>
                    <module name="Magento_Eav"/>
                </sequence>
            </module>
        </config>

db_schema.xml

                <?xml version="1.0"?>
        <!--
        /*
         * Copyright © 2019 Krish Technolabs. All rights reserved.
         * See COPYING.txt for license details
         */
        -->
        <schema xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:Setup/Declaration/Schema/etc/schema.xsd">
            <table comment="Test Table 1" engine="innodb" name="ktpl_test1" resource="default">
                <column identity="true" name="test1_id" nullable="false" padding="10" unsigned="true" xsi:type="int"/>
                <column  name="test_name" nullable="false" padding="10" unsigned="true" xsi:type="int"/>
                <column   name="test2_id" nullable="false" padding="10" unsigned="true" xsi:type="int"/>
                <constraint referenceId="PRIMARY" xsi:type="primary">
                    <column name="test1_id"/>
                </constraint>
               <constraint xsi:type="foreign" referenceId="Test12ID" table="ktpl_test1" column="test2_id" referenceTable ="ktpl_test2" referenceColumn="test2_id"/>
               <constraint xsi:type="foreign" referenceId="Test13ID" table="ktpl_test1" column="test3_id" referenceTable ="ktpl_test3" referenceColumn="test3_id"/>
            </table>
             <table name="eav_attribute" resource="default" engine="innodb" comment="Eav Attribute">
                <column xsi:type="mediumtext" name="note" nullable="false" length="500" comment="Note"/>
                <constraint xsi:type="primary" referenceId="PRIMARY">
                    <column name="attribute_id"/>
                </constraint>
            </table>
        </schema>

Answer 1

The only mistake you are doing here is length attribute, just remove it.

This is the working code..

etc\db_schema.xml

<?xml version="1.0"?>

<schema xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:Setup/Declaration/Schema/etc/schema.xsd">
    <table name="eav_attribute" resource="default" engine="innodb" comment="Eav Attribute">
        <column xsi:type="mediumtext" name="note" nullable="true" comment="Note"/>
    </table>
</schema>

Answer 2

Create db_schema.xml file in your module and add this below code :

app/code/VendorName/ModuleName/etc/db_schema.xml

<schema xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:Setup/Declaration/Schema/etc/schema.xsd">
    <table name="eav_attribute">
        <column xsi:type="mediumtext" name="note" nullable="true" length="255" comment="Note"/>
        <constraint xsi:type="primary" referenceId="PRIMARY">
            <column name="attribute_id"/>
        </constraint>
    </table>
</schema>

Now, execute this below command in your Magento root directory

php bin/magento setup:db-declaration:generate-whitelist --module-name=VendorName_ModuleName

Make sure, there are db_whitelist_schema.json file will be create in app/code/VendorName/ModuleName/etc folder.

Now, upgrade, deploy and clean cache

php bin/magento s:up
php bin/magento s:s:d -f
php bin/magento c:c

Hope, it will helpful for you.

---

UPDATE :

de_whitelist_schema.json (After install ktpl_test1 table) :

{
    "ktpl_test1": {
        "column": {
            "test1_id": true,
            "test_name": true,
            "test2_id": true
        },
        "constraint": {
            "PRIMARY": true
        }
    },
    "eav_attribute": {
        "column": {
            "note": true
        },
        "constraint": {
            "PRIMARY": true
        }
    }
}

Answer 3

As far as I know, it's not possible in magento 2 right now. There is also an issue related to chaning the column type: Table quote column customer_note uses wrong type

This is my fix for that issue:

use Magento\Framework\Setup\Declaration\Schema\Declaration\ReaderComposite;

class ReaderCompositePlugin
{
    public function afterRead(ReaderComposite $subject, $result)
    {
        if (isset($result['table']['quote']) && isset($result['table']['quote']['column']['customer_note'])) {
            $result['table']['quote']['column']['customer_note']['type'] = 'text';
            unset($result['table']['quote']['column']['customer_note']['length']);
        }

        return $result;
    }
}