Database Seeding

Seed classes are a great way to easily fill your database with data after it's created. By default, they are stored in the config/Seeds directory.

NOTE

Database seeding is entirely optional, and Migrations does not create a Seeds directory by default.

Creating a New Seed Class

Migrations includes a command to easily generate a new seed class:

$ bin/cake bake seed MyNewSeed

By default, it generates a traditional seed class with a named class:

<?php
declare(strict_types=1);

use Migrations\BaseSeed;

class MyNewSeed extends BaseSeed
{
    /**
     * Run Method.
     *
     * Write your database seed using this method.
     *
     * More information on writing seeds is available here:
     * https://book.cakephp.org/migrations/5/en/seeding.html
     */
    public function run() : void
    {

    }
}

By default, the table the seed will try to alter is the "tableized" version of the seed filename.

Seed Naming

When referencing seeds in your code or via the command line, you can use either:

• The short name without the Seed suffix (e.g., Articles, Users)
• The full name with the Seed suffix (e.g., ArticlesSeed, UsersSeed)

Both forms work identically in:

• Command line: --seed Articles or --seed ArticlesSeed
• Dependencies: return ['User', 'ShopItem']; or return ['UserSeed', 'ShopItemSeed'];
• Calling seeds: $this->call('Articles'); or $this->call('ArticlesSeed');

Using the short name is recommended for cleaner, more concise code.

Anonymous Seed Classes

Migrations also supports generating anonymous seed classes, which use PHP's anonymous class feature instead of named classes. This style is useful for:

• Avoiding namespace declarations
• Better PHPCS compatibility (no class name to filename matching required)
• Simpler file structure without named class constraints

To generate an anonymous seed class, use the --style anonymous option:

$ bin/cake bake seed MyNewSeed --style anonymous

This generates a seed file using an anonymous class:

<?php
declare(strict_types=1);

use Migrations\BaseSeed;

return new class extends BaseSeed
{
    /**
     * Run Method.
     *
     * Write your database seeder using this method.
     *
     * More information on writing seeds is available here:
     * https://book.cakephp.org/migrations/5/en/seeding.html
     */
    public function run(): void
    {

    }
};

Both traditional and anonymous seed classes work identically at runtime and can be used interchangeably within the same project.

You can set the default seed style globally in your application configuration:

// In config/app.php or config/app_local.php
'Migrations' => [
    'style' => 'anonymous',  // or 'traditional'
],

Seed Options

# you specify the name of the table the seed files will alter by using the ``--table`` option
bin/cake bake seed articles --table my_articles_table
# You can specify a plugin to bake into
bin/cake bake seed Articles --plugin PluginName

# You can specify an alternative connection when generating a seed.
bin/cake bake seed Articles --connection connection

# Include data from the Articles table in your seed.
bin/cake bake seed --data Articles

By default, it will export all the rows found in your table. You can limit the number of rows exported by using the --limit option:

# Will only export the first 10 rows found
bin/cake bake seed --data --limit 10 Articles

If you only want to include a selection of fields from the table in your seed file, you can use the --fields option. It takes the list of fields to include as a comma separated value string:

# Will only export the fields `id`, `title` and `excerpt`
bin/cake bake seed --data --fields id,title,excerpt Articles

TIP

Of course you can use both the --limit and --fields options in the same command call.

Customizing Seed and Migration templates

Because migrations uses bake under the hood you can customize the templates that migrations uses for creating seeds and migrations by creating templates in your application. Custom templates for migrations should be on one of the following paths:

• ROOT/templates/plugin/Migrations/bake/
• ROOT/templates/bake/

For example, the seed templates are:

• Traditional: Seed/seed.twig at ROOT/templates/plugin/Migrations/bake/Seed/seed.twig
• Anonymous: Seed/seed-anonymous.twig at ROOT/templates/plugin/Migrations/bake/Seed/seed-anonymous.twig

The BaseSeed Class

All Migrations seeds extend from the BaseSeed class. It provides the necessary support to create your seed classes. Seed classes are primarily used to insert test data.

The Run Method

The run method is automatically invoked by Migrations when you execute the cake seeds run command. You should use this method to insert your test data.

Seed Execution Tracking

Seeds track their execution state in the cake_seeds database table. By default, a seed will only run once. If you attempt to run a seed that has already been executed, it will be skipped with an "already executed" message.

To re-run a seed that has already been executed, use the --force flag:

bin/cake seeds run Users --force

You can check which seeds have been executed using the status command:

bin/cake seeds status

To reset all seeds' execution state (allowing them to run again without --force):

bin/cake seeds reset

NOTE

When re-running seeds with --force, be careful to ensure your seeds are idempotent (safe to run multiple times) or they may create duplicate data.

Customizing the Seed Tracking Table

By default, seed execution is tracked in a table named cake_seeds. You can customize this table name by configuring it in your config/app.php or config/app_local.php:

'Migrations' => [
    'seed_table' => 'my_custom_seeds_table',
],

This is useful if you need to avoid table name conflicts or want to follow a specific naming convention in your database.

Idempotent Seeds

Some seeds are designed to be run multiple times safely (idempotent), such as seeds that update configuration or reference data. For these seeds, you can override the isIdempotent() method:

<?php
declare(strict_types=1);

use Migrations\BaseSeed;

class ConfigSeed extends BaseSeed
{
    /**
     * Mark this seed as idempotent.
     * It will run every time it is invoked.
     */
    public function isIdempotent(): bool
    {
        return true;
    }

    public function run(): void
    {
        // This seed will run every time, so make it safe to run multiple times
        $this->execute("
            INSERT INTO settings (setting_key, setting_value)
            VALUES ('app_version', '2.0.0')
            ON DUPLICATE KEY UPDATE setting_value = '2.0.0'
        ");

        // Or check before inserting
        $exists = $this->fetchRow(
            "SELECT COUNT(*) as count FROM settings WHERE setting_key = 'maintenance_mode'"
        );

        if ($exists['count'] == 0) {
            $this->table('settings')->insert([
                'setting_key' => 'maintenance_mode',
                'setting_value' => 'false',
            ])->save();
        }
    }
}

When isIdempotent() returns true:

• The seed will run every time you execute seeds run
• The last execution time is still tracked in the cake_seeds table
• The seeds status command will show the seed as (idempotent)
• You must ensure the seed's run() method handles duplicate executions safely

This is useful for:

• Configuration seeds that should always reflect current values
• Reference data that may need periodic updates
• Seeds that use INSERT ... ON DUPLICATE KEY UPDATE or similar patterns
• Development/testing seeds that need to run repeatedly

WARNING

Only mark a seed as idempotent if you've verified it's safe to run multiple times. Otherwise, you may create duplicate data or other unexpected behavior.

The Init Method

The init() method is run by Migrations before the run method if it exists. This can be used to initialize properties of the Seed class before using run.

The Should Execute Method

The shouldExecute() method is run by Migrations before executing the seed. This can be used to prevent the seed from being executed at this time. It always returns true by default. You can override it in your custom BaseSeed implementation.

Foreign Key Dependencies

Often you'll find that seeds need to run in a particular order, so they don't violate foreign key constraints. To define this order, you can implement the getDependencies() method that returns an array of seeds to run before the current seed:

<?php

use Migrations\BaseSeed;

class ShoppingCartSeed extends BaseSeed
{
    public function getDependencies(): array
    {
        return [
            'User',      // Short name without 'Seed' suffix
            'ShopItem',  // Short name without 'Seed' suffix
        ];
    }

    public function run() : void
    {
        // Seed the shopping cart after the `UserSeed` and
        // `ShopItemSeed` have been run.
    }
}

You can also use the full seed name including the Seed suffix:

return [
    'UserSeed',
    'ShopItemSeed',
];

Both forms are supported and work identically.

Automatic Dependency Execution

When you run a seed that has dependencies, the system will automatically check if those dependencies have been executed. If any dependencies haven't run yet, they will be executed automatically before the current seed runs. This ensures proper execution order and prevents foreign key constraint violations.

For example, if you run:

bin/cake seeds run ShoppingCartSeed

And ShoppingCartSeed depends on UserSeed and ShopItemSeed, the system will automatically execute those dependencies first if they haven't been run yet.

NOTE

Dependencies that have already been executed (according to the cake_seeds table) will be skipped, unless you use the --force flag which will re-execute all seeds including dependencies.

Calling a Seed from another Seed

Usually when seeding, the order in which to insert the data must be respected to not encounter constraint violations. Since seeds are executed in an alphabetical order by default, you can use the \Migrations\BaseSeed::call() method to define your own sequence of seeds execution:

<?php

use Migrations\BaseSeed;

class DatabaseSeed extends BaseSeed
{
    public function run(): void
    {
        $this->call('Another');      // Short name without 'Seed' suffix
        $this->call('YetAnother');   // Short name without 'Seed' suffix

        // You can use the plugin dot syntax to call seeds from a plugin
        $this->call('PluginName.FromPlugin');
    }
}

You can also use the full seed name including the Seed suffix:

$this->call('AnotherSeed');
$this->call('YetAnotherSeed');
$this->call('PluginName.FromPluginSeed');

Both forms are supported and work identically.

Inserting Data

Seed classes can also use the familiar Table object to insert data. You can retrieve an instance of the Table object by calling the table() method from within your seed class and then use the insert() method to insert data:

<?php

use Migrations\BaseSeed;

class PostsSeed extends BaseSeed
{
    public function run() : void
    {
        $data = [
            [
                'body'    => 'foo',
                'created' => date('Y-m-d H:i:s'),
            ],[
                'body'    => 'bar',
                'created' => date('Y-m-d H:i:s'),
            ]
        ];

        $posts = $this->table('posts');
        $posts->insert($data)
              ->saveData();
    }
}

NOTE

You must call the saveData() method to commit your data to the table. Migrations will buffer data until you do so.

Insert Modes

In addition to the standard insert() method, Migrations provides specialized insert methods for handling conflicts with existing data.

Insert or Skip

The insertOrSkip() method inserts rows but silently skips any that would violate a unique constraint:

<?php

use Migrations\BaseSeed;

class CurrencySeed extends BaseSeed
{
    public function run(): void
    {
        $data = [
            ['code' => 'USD', 'name' => 'US Dollar'],
            ['code' => 'EUR', 'name' => 'Euro'],
        ];

        $this->table('currencies')
            ->insertOrSkip($data)
            ->saveData();
    }
}

Insert or Update (Upsert)

The insertOrUpdate() method performs an "upsert" operation - inserting new rows and updating existing rows that conflict on unique columns:

<?php

use Migrations\BaseSeed;

class ExchangeRateSeed extends BaseSeed
{
    public function run(): void
    {
        $data = [
            ['code' => 'USD', 'rate' => 1.0000],
            ['code' => 'EUR', 'rate' => 0.9234],
        ];

        $this->table('exchange_rates')
            ->insertOrUpdate($data, ['rate'], ['code'])
            ->saveData();
    }
}

The method takes three arguments:

• $data: The rows to insert (same format as insert())
• $updateColumns: Which columns to update when a conflict occurs
• $conflictColumns: Which columns define uniqueness (must have a unique index)

WARNING

Database-specific behavior differences:

MySQL: Uses ON DUPLICATE KEY UPDATE. The $conflictColumns parameter is ignored because MySQL automatically applies the update to all unique constraint violations on the table. Passing $conflictColumns will trigger a warning. If your table has multiple unique constraints, be aware that a conflict on any of them will trigger the update.

PostgreSQL/SQLite: Uses ON CONFLICT (...) DO UPDATE SET. The $conflictColumns parameter is required and specifies exactly which unique constraint should trigger the update. A RuntimeException will be thrown if this parameter is empty.

SQL Server: Not currently supported. Use separate insert/update logic.

Truncating Tables

In addition to inserting data Migrations makes it trivial to empty your tables using the SQL TRUNCATE command:

<?php

use Migrations\BaseSeed;

class UserSeed extends BaseSeed
{
    public function run() : void
    {
        $data = [
            [
                'body'    => 'foo',
                'created' => date('Y-m-d H:i:s'),
            ],
            [
                'body'    => 'bar',
                'created' => date('Y-m-d H:i:s'),
            ]
        ];

        $posts = $this->table('posts');
        $posts->insert($data)
              ->saveData();

        // empty the table
        $posts->truncate();
    }
}

NOTE

SQLite doesn't natively support the TRUNCATE command so behind the scenes DELETE FROM is used. It is recommended to call the VACUUM command after truncating a table. Migrations does not do this automatically.

Executing Seed Classes

This is the easy part. To seed your database, simply use the seeds run command:

$ bin/cake seeds run

By default, Migrations will execute all available seed classes. If you would like to run a specific seed, simply pass in the seed name as an argument. You can use either the short name (without the Seed suffix) or the full name:

$ bin/cake seeds run User
# or
$ bin/cake seeds run UserSeed

Both commands work identically.

You can also run multiple seeds by separating them with commas:

$ bin/cake seeds run User,Permission,Log
# or with full names
$ bin/cake seeds run UserSeed,PermissionSeed,LogSeed

You can also use the -v parameter for more output verbosity:

$ bin/cake seeds run -v

The Migrations seed functionality provides a simple mechanism to easily and repeatably insert test data into your database, this is great for development environment sample data or getting state for demos.