module.xml Deep Dive

Beyond the basics, module.xml supports several advanced attributes for module control.

Complete module.xml schema:

<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
        xsi:noNamespaceSchemaLocation="urn:magento:framework:Module/etc/module.xsd">
    <module name="Vendor_Module" setup_version="1.2.0" component_type="module">
        <sequence>
            <module name="Magento_Catalog"/>
            <module name="Magento_Inventory"/>
        </sequence>
        <suggest>
            <module name="Magento_Elasticsearch"/>
        </suggest>
    </module>
</config>

Attributes explained:

component_type values:

• module — Standard PHP module (most common)
• theme — Magento theme component
• language — Translation package
• library — Shared library component

Example — Language package:

<module name="Vendor_Module_de_DE" component_type="language" setup_version="1.0.0">
    <sequence>
        <module name="Vendor_Module"/>
    </sequence>
</module>

Understanding how sequence dependencies affect module loading, upgrades, and configuration.

Dependency resolution order:

1. Magento_Store (always first)
2. Magento_Directory
3. ... other core modules ...
4. Your module's dependencies
5. Your module

What sequence affects:

1. Load order:

php bin/magento module:status --dependencies
# Shows the resolved dependency order

2. Schema upgrade order:

- Dependencies upgrade BEFORE your module
- Your module upgrades AFTER dependencies
- Ensures tables/columns exist before you reference them

3. Configuration merge order:

- Dependencies' XML files merge first
- Your XML files merge second
- Your config can override dependency config

4. Code generation order:

- Dependencies are compiled first
- Generated classes are available for your module

Dependency pitfalls:

<!-- BAD: Circular dependency -->
<!-- Module A depends on B -->
<module name="Vendor_A">
    <sequence><module name="Vendor_B"/></sequence>
</module>

<!-- Module B depends on A -->
<module name="Vendor_B">
    <sequence><module name="Vendor_A"/></sequence>
</module>

<!-- GOOD: Unidirectional -->
<module name="Vendor_A">
    <sequence><module name="Vendor_B"/></sequence>
</module>
<module name="Vendor_B">
    <!-- No dependency on A -->
</module>

Soft vs Hard dependencies:

<!-- Hard: Module MUST exist and load first -->
<sequence>
    <module name="Magento_Catalog"/>
</sequence>

<!-- Soft: Module MAY exist, enhances functionality -->
<suggest>
    <module name="Magento_Elasticsearch"/>
</suggest>

Check dependency chains:

# Full dependency tree
php bin/magento module:status --dependencies | grep -A 5 Vendor_Module

Setup scripts handle database schema creation and data migration.

Setup script locations:

app/code/Vendor/Module/Setup/
├── InstallSchema.php        # First installation
├── UpgradeSchema.php        # Schema changes per version
├── InstallData.php           # Initial data seeding
├── UpgradeData.php           # Data changes per version
├── Recurring.php            # Runs on every setup:upgrade
└── Patch/
    └── Data/
        └── AddCustomAttribute.php  # Data patches (2.4+)

InstallSchema.php:

<?php
namespace Vendor\Module\Setup;

use Magento\Framework\Setup\ModuleContextInterface;
use Magento\Framework\Setup\SchemaSetupInterface;

class InstallSchema implements \Magento\Framework\Setup\InstallSchemaInterface
{
    public function install(SchemaSetupInterface $setup, ModuleContextInterface $context)
    {
        $setup->startSetup();
        
        $table = $setup->getConnection()->newTable(
            $setup->getTable('vendor_module_items')
        )
        ->addColumn(
            'entity_id',
            \Magento\Framework\Db\Ddl\Table::TYPE_INTEGER,
            null,
            ['identity' => true, 'unsigned' => true, 'nullable' => false, 'primary' => true],
            'Entity ID'
        )
        ->addColumn(
            'name',
            \Magento\Framework\Db\Ddl\Table::TYPE_TEXT,
            255,
            ['nullable' => false],
            'Name'
        );
        
        $setup->getConnection()->createTable($table);
        $setup->endSetup();
    }
}

UpgradeSchema.php:

public function upgrade(SchemaSetupInterface $setup, ModuleContextInterface $context)
{
    $setup->startSetup();
    
    if (version_compare($context->getVersion(), '1.1.0', '<')) {
        $setup->getConnection()->addColumn(
            $setup->getTable('vendor_module_items'),
            'description',
            [
                'type' => \Magento\Framework\Db\Ddl\Table::TYPE_TEXT,
                'nullable' => true,
                'comment' => 'Description'
            ]
        );
    }
    
    $setup->endSetup();
}

Managing module state through command line and database.

Module status commands:

# List all modules and their status
php bin/magento module:status

# Enable a module
php bin/magento module:enable Vendor_Module

# Disable a module
php bin/magento module:disable Vendor_Module

# Check specific module status
php bin/magento module:status Vendor_Module

# Enable with dependency check
php bin/magento module:enable Vendor_Module --force

Disabled flag in module.xml:

<!-- Module is disabled in XML (not recommended) -->
<module name="Vendor_Module" setup_version="1.0.0" disabled="true">
    <sequence>
        <module name="Magento_Catalog"/>
    </sequence>
</module>

Module state in database:

-- Check module version in DB
SELECT * FROM setup_module WHERE module = 'Vendor_Module';

-- Module enabled/disabled state
SELECT * FROM module_status WHERE module = 'Vendor_Module';

-- Force module state
UPDATE module_status SET is_enabled = 1 WHERE module = 'Vendor_Module';

Module registration lifecycle:

1. Create module files (module.xml, registration.php)
2. Run php bin/magento module:enable Vendor_Module
3. Run php bin/magento setup:upgrade
4. Module appears in generated code

Removing a module:

# Disable module
php bin/magento module:disable Vendor_Module

# Remove database tables (manual)
# Run setup:upgrade to clean up
php bin/magento setup:upgrade

# Clean generated code
rm -rf generated/code/Vendor/Module/
php bin/magento setup:di:compile

Common module issues:

# Module not appearing
php bin/magento module:status | grep Vendor_Module
# Check: registration.php exists? module.xml exists?

# Version mismatch
php bin/magento setup:upgrade
# Check setup_version matches DB record

# Dependency not found
php bin/magento module:status --dependencies
# Ensure dependency module is installed and enabled