codebar-ag/migrations

Migrations

When to Apply

• Apply for schema changes: tables, columns, indexes, foreign keys, constraints.
• Apply when rollout/rollback behavior must be explicit and versioned.
• Do not use for long-running data backfills or one-off data repair scripts.
• For zero-downtime rollout strategies, pair this skill with deployment/runbook guidance.

Preconditions

• Database connection and target environment are known.
• Migration file naming follows timestamp prefix ordering.
• Risky operations (dropColumn, type changes, destructive renames) are reviewed with backup/rollback plan.

Process

1. Create a New Migration File

• Never edit previously committed migration files.
• Use descriptive names, for example add_status_to_invoices_table.
• Generate with Laravel command:
  • php artisan make:migration add_status_to_invoices_table --table=invoices

2. Implement up() with Focused Changes

• Keep one concern per migration.
• Add indexes for foreign keys and common filters.
• Prefer string-backed status columns for enum-like states.

3. Implement Safe down() Reversal

• Reverse every structural change in up() where possible.
• Document irreversible/data-loss risks in comments and PR notes.
• Remember: dropping a column restores schema only; removed data is not recovered.

4. Validate Migration Lifecycle

• Run php artisan migrate and php artisan migrate:rollback --step=1 locally.
• Confirm table timestamps behavior explicitly when removing timestamps:
  • $table->dropTimestamps(); (drops created_at and updated_at together).

Examples

public function up(): void
{
    Schema::create('invoices', function (Blueprint $table) {
        $table->id();
        $table->foreignId('order_id')->constrained()->cascadeOnDelete();
        $table->foreignId('user_id')->constrained()->cascadeOnDelete();
        $table->string('status')->default('draft');
        $table->decimal('amount', 10, 2);
        $table->date('due_date');
        $table->timestamp('paid_at')->nullable();
        $table->timestamps();

        $table->index('status');
    });
}

public function down(): void
{
    Schema::dropIfExists('invoices');
}

// Adding a column to an existing table
public function up(): void
{
    Schema::table('invoices', function (Blueprint $table) {
        $table->string('reference')->nullable()->after('status');
    });
}

public function down(): void
{
    Schema::table('invoices', function (Blueprint $table) {
        $table->dropColumn('reference');
    });
}

// Dropping timestamps explicitly (schema reversal only, not data recovery)
public function up(): void
{
    Schema::table('invoices', function (Blueprint $table) {
        $table->dropTimestamps();
    });
}

public function down(): void
{
    Schema::table('invoices', function (Blueprint $table) {
        $table->timestamps();
    });
}

Checklists

• [ ] Migration is new (no edits to existing historical migrations).
• [ ] File name is descriptive and timestamp ordered.
• [ ] up() and down() are implemented and tested locally.
• [ ] Destructive operations include rollback and data-loss notes.
• [ ] Indexes/foreign keys are added for query and integrity needs.

Anti-Patterns

• Modifying existing migration files instead of creating new ones
• Omitting the down() method or leaving it empty
• Not adding indexes on foreign key columns and frequently queried columns
• Creating a single migration that makes multiple unrelated schema changes
• Using integer status defaults when domain status is a named state (draft, paid, cancelled)
• Assuming down() can recover data that was dropped in up()

References

• Laravel Migrations
• Laravel Migration Events and Commands
• resources/boost/skills/models/SKILL.md (schema-to-model alignment)
• resources/boost/skills/enums/SKILL.md (status value conventions)