How to Create a New Table using Declarative Schema in Magento 2

Magento 2 introduced an innovative feature called Declarative Schema. This new approach simplifies the process of managing database schema changes and eliminates the need for writing repetitive SQL scripts for schema updates. In this blog post, we will guide you through the steps to create a new table using Declarative Schema in Magento 2.

Why Declarative Schema?

Before we dive into the implementation, let’s understand the benefits of using Declarative Schema:

1. Simplicity: No need to write complex install/upgrade scripts.
2. Reliability: Ensures consistency across different environments.
3. Maintainability: Easier to manage and understand schema changes.

Step-by-Step Guide to Creating a New Table

Step 1: Set Up Your Module

Before creating a new table, ensure that you have a custom module. If you don’t have one, you can create it by following these steps:

1. Create Directory Structure:

   app/code/YourVendor/YourModule

2. Create module.xml:

   <?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="YourVendor_YourModule" setup_version="1.0.0"/>
   </config>

Save this file in app/code/YourVendor/YourModule/etc/module.xml.

3. Create registration.php:

   <?php
   \Magento\Framework\Component\ComponentRegistrar::register(
       \Magento\Framework\Component\ComponentRegistrar::MODULE,
       'YourVendor_YourModule',
       __DIR__
   );

Save this file in app/code/YourVendor/YourModule/registration.php.

Step 2: Define the New Table

1. Create db_schema.xml:
   Create a file named db_schema.xml in app/code/YourVendor/YourModule/etc with the following content:

   <?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="your_new_table" resource="default" engine="innodb" comment="Your New Table">
           <column xsi:type="int" name="entity_id" nullable="false" identity="true" comment="Entity ID"/>
           <column xsi:type="varchar" name="name" nullable="false" length="255" comment="Name"/>
           <column xsi:type="text" name="description" nullable="true" comment="Description"/>
           <column xsi:type="timestamp" name="created_at" nullable="false" default="CURRENT_TIMESTAMP" comment="Creation Time"/>
           <constraint xsi:type="primary" referenceId="PRIMARY">
               <column name="entity_id"/>
           </constraint>
       </table>
   </schema>

Step 3: Declare the Schema in the Module

Ensure that your module is properly configured to use the Declarative Schema. Update your module’s etc/module.xml file if necessary to reflect the correct setup version.

Step 4: Run the Setup Upgrade Command

After defining the schema, run the following command to apply the changes:

php bin/magento setup:upgrade

This command will read the db_schema.xml file and create the new table in your database.

Step 5: Verify the Table Creation

To ensure that the table has been created, you can check your database using a database management tool like phpMyAdmin or MySQL Workbench. You should see the your_new_table with the defined columns and constraints.

Conclusion

Creating a new table using Declarative Schema in Magento 2 is straightforward and efficient. By following the steps outlined above, you can easily manage database schema changes, ensuring consistency and maintainability in your Magento 2 projects.

If you have any questions or run into issues, feel free to leave a comment below. Happy coding!

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