Go Ent Migration

In this tutorial, you'll learn about Ent Migration: Schema Drift. We cover key concepts, practical examples, and best practices.

Ent database migrations -- Run Ent schema migrations safely in production using the atlas migration engine.

The Problem

Schema.Create() creates tables but is not safe for production. Ent recommends atlas-generated versioned migrations.

Wrong

if err := client.Schema.Create(ctx); err != nil { log.Fatal(err) }

Output:

// Works in dev, but unsafe for production schema changes

Right

// atlas-based versioned migration:
// go run entgo.io/ent/cmd/entc init
// Generates versioned SQL migration files

Output:

// 20260624_100000_initial.up.sql
// Versioned and reversible

Prevention

• Use atlas-based migrations for production
• Always review generated SQL before applying
• Test on staging first
• Use atlas migrate apply for deployment
• Keep migrations in version control

Common Mistakes with ent migration

1. Using return to exit a function early instead of wrapping a pure value in the monad
2. Mixing let bindings with <- bindings in do notation, producing type errors
3. Overlapping type class instances that cause GHC to reject the program with ambiguous dispatch errors

These mistakes appear frequently in real-world GO code. DodaTech's contributors have identified these patterns through analysis of open-source projects and production systems.

Practice Exercise

Write a pure function that safely divides two integers using Maybe, then test it with edge cases like division by zero and negative numbers.

This exercise reinforces the concepts covered in this guide. Try implementing it before checking online solutions.

FAQ

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