GORM Setup for Go Web Application

GORM Setup for Go Web Application

GORM is the most popular ORM for Go. It doesn't try to hide SQL completely, giving direct access to raw queries where needed. Version v2 is incompatible with v1 API-wise.

go get gorm.io/gorm
go get gorm.io/driver/postgres

Initialization

package db

import (
    "gorm.io/driver/postgres"
    "gorm.io/gorm"
    "gorm.io/gorm/logger"
    "log"
    "time"
)

func New(dsn string) (*gorm.DB, error) {
    db, err := gorm.Open(postgres.New(postgres.Config{
        DSN:                  dsn,
        PreferSimpleProtocol: true,
    }), &gorm.Config{
        Logger:      logger.Default.LogMode(logger.Warn),
        NowFunc:    func() time.Time { return time.Now().UTC() },
    })

    sqlDB, _ := db.DB()
    sqlDB.SetMaxOpenConns(25)
    sqlDB.SetMaxIdleConns(10)
    sqlDB.SetConnMaxLifetime(5 * time.Minute)

    return db, err
}

Models

type Product struct {
    ID         uint           `gorm:"primarykey"`
    CreatedAt  time.Time
    UpdatedAt  time.Time
    DeletedAt  gorm.DeletedAt `gorm:"index"`

    Title      string        `gorm:"type:varchar(500);not null"`
    Slug       string        `gorm:"type:varchar(520);uniqueIndex"`
    Price      float64       `gorm:"type:decimal(12,2)"`
    Status     ProductStatus `gorm:"type:varchar(20);default:draft"`
    CategoryID uint          `gorm:"not null;index"`
    Category   Category      `gorm:"foreignKey:CategoryID;constraint:OnDelete:RESTRICT"`
    Tags       []Tag         `gorm:"many2many:product_tags;"`
}

func (Product) TableName() string {
    return "products"
}

Queries

type ProductRepository struct {
    db *gorm.DB
}

func (r *ProductRepository) GetPublished(
    ctx context.Context,
    categoryID uint,
    limit, offset int,
) ([]Product, error) {
    var products []Product
    err := r.db.WithContext(ctx).
        Preload("Category").
        Preload("Tags").
        Where("category_id = ? AND status = ?", categoryID, "published").
        Order("created_at DESC").
        Limit(limit).
        Offset(offset).
        Find(&products).Error
    return products, err
}

Migrations

Use golang-migrate for production:

go install -tags 'postgres' github.com/golang-migrate/migrate/v4/cmd/migrate@latest
migrate create -ext sql -dir migrations -seq create_products

Timeline

Initial GORM setup with golang-migrate: 1 day.