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Kengo Wada
Kengo Wada

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GORM and Goose Migrations

#go #gorm #goose

Let's get started with handling migrations in Go with GORM and Goose.

Prerequisites

  • Go installed
  • GORM Supported SQL Database(I'll be using Postgresql)

Note:
You may refer to this repo for the file structure.

Install Goose Locally

Follow the steps here to install Goose for your operating system.

I tried using the installation script with Ubuntu 20.04 but I run into errors and found a solution here

wget http://github.com/golang-migrate/migrate/releases/latest/download/migrate.linux-amd64.deb
sudo dpkg -i migrate.linux-amd64.deb

goose --help // To test if install went well.
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Start Dummy Project

  • Create a directory 
mkdir app
cd app
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  • Initialize it as a Go project 
go mod init app
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  • Create main.go in the root of your project 
package main

func main() {

}
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Getting Started With GORM

  • Create database directory 
mkdir database
cd database
touch postgres.go
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  • Add the following to database/postgres.go 
package database

import (
    "database/sql"
    "os"

    "gorm.io/driver/postgres"
    "gorm.io/gorm"
)

var dbURL := os.Getenv("GOOSE_DBSTRING")

var GORM_DB *gorm.DB
var SQL_DB *sql.DB
var DB_MIGRATOR gorm.Migrator

func ConnectToDatabase() (error) {
    db, err := gorm.Open(postgres.Open(dbURL), &gorm.Config{})
    if err == nil {
        GORM_DB = db
        SQL_DB, _ = db.DB()
        DB_MIGRATOR = db.Migrator()
    }
    return err
}
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  • At this point you'll have failed import errors, so let's fix that 
go mod tidy
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  • Now create env in your projects root directory 
mkdir env
touch env/goose.env
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  • Add the following to env/goose.env 
export GOOSE_DRIVER='postgres'
export GOOSE_DBSTRING='postgres://user:password@localhost:5432/db_name?sslmode=disable'
export GOOSE_MIGRATION_DIR='./migrations'
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  • Now source the environment variables 
source env/goose.env
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Creating Models and Migrations

  • Create a models directory in your projects root directory 
mkdir models
touch models/user.go
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  • Add the following to models/user.go 
package models

import (
    "gorm.io/gorm"
)

type User struct {
    *gorm.Model
    Name     string
    Email    string
    Password string
}
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  • Now run goose command to create migration file 
mkdir migrations
goose -s create create_user
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  • After this, you'll have import errors. Let's fix this 
go mod tidy
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  • Update the 00001_create_user.go file to have the following 
package migrations

import (
    "app/database"
    "app/models"
    "context"
    "database/sql"

    "github.com/pressly/goose/v3"
)

func init() {
    goose.AddMigrationContext(upCreateUser, downCreateUser)
}

func upCreateUser(ctx context.Context, tx *sql.Tx) error {
    return database.DB_MIGRATOR.CreateTable(&models.User{})
}

func downCreateUser(ctx context.Context, tx *sql.Tx) error {
    return database.DB_MIGRATOR.DropTable(&models.User{})
}
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Bringing It All Together

  • Update the main.go file to have the following 
package main

import (
    "app/database"
    _ "app/migrations" // This loads the migrations init functions

    "github.com/pressly/goose/v3"
)

func main() {
    err := database.ConnectToDatabase()
    if err != nil {
        panic(err)
    }

    if err := goose.SetDialect("postgres"); err != nil {
        panic(err)
    }
    if err := goose.Up(database.SQL_DB, "migrations"); err != nil {
        panic(err)
    }
    // Start server...
}
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  • Now you can run migrations before starting the server 
go run .
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Top comments (1)

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__59cdb67 profile image
Руслан Искандаров • • Edited

I got this error when running my main.go
failed to run Go migration: Go functions must be registered and built into a custom binary

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