goodm

A schema-driven ODM for MongoDB in Go.

Define your models as Go structs, and goodm handles validation, hooks, indexes, immutability, references, middleware, aggregation, bulk operations, and transactions.

type User struct {
    goodm.Model `bson:",inline"`
    Email       string `bson:"email" goodm:"unique,required"`
    Name        string `bson:"name"  goodm:"required,immutable"`
    Age         int    `bson:"age"   goodm:"min=13,max=120"`
    Role        string `bson:"role"  goodm:"enum=admin|user|mod,default=user"`
}

func init() {
    goodm.Register(&User{}, "users")
}

Your struct is the schema. Tags declare constraints, indexes, and references. The ODM enforces them on every write.

Why goodm?

Go has a strong MongoDB driver, but no mature ODM that treats Go structs as the schema contract:

• Prisma dropped Go support. That door is closed.
• The official mongo-driver is low-level. You get bson.D and Collection.InsertOne — everything else is left to you.
• Mongoose proved the pattern. Node.js developers have had schema-as-code with lifecycle hooks, population, and middleware for over a decade. Go deserves the same.

Quick Start

Install

go get github.com/dwoolworth/goodm

CLI (optional):

go install github.com/dwoolworth/goodm/cmd/goodm@latest

Connect and Create

package main

import (
    "context"
    "log"

    "github.com/dwoolworth/goodm"
    "go.mongodb.org/mongo-driver/v2/bson"
)

type User struct {
    goodm.Model `bson:",inline"`
    Email       string `bson:"email" goodm:"unique,required"`
    Name        string `bson:"name"  goodm:"required,immutable"`
    Age         int    `bson:"age"   goodm:"min=13,max=120"`
}

func init() {
    goodm.Register(&User{}, "users")
}

func main() {
    ctx := context.Background()

    db, _ := goodm.Connect(ctx, "mongodb://localhost:27017", "myapp")
    goodm.Enforce(ctx, db)

    // Create
    user := &User{Email: "alice@example.com", Name: "Alice", Age: 30}
    goodm.Create(ctx, user)

    // Read
    found := &User{}
    goodm.FindOne(ctx, bson.D{{Key: "email", Value: "alice@example.com"}}, found)

    // Update
    found.Age = 31
    goodm.Update(ctx, found)

    // Delete
    goodm.Delete(ctx, found)
}

Features

Feature	What it does
Schema Tags	unique, index[=kind], sparse, ttl, required, immutable, default, enum, min, max, ref
CRUD	Create, FindOne, FindByID, Find, FindCursor, Count, Exists, Distinct, Update, UpdateFields, Delete
Atomic	FindOneAndUpdate, FindOneAndReplace, FindOneAndDelete with upsert
Raw Operations	UpdateOne, DeleteOne, UpdateMany, DeleteMany, NewBulk for direct MongoDB access
Hooks	BeforeCreate, AfterCreate, BeforeSave, AfterSave, BeforeDelete, AfterDelete
Validation	Automatic on Create/Update: required, enum, min/max, immutable enforcement; Enforce can install the same rules as a $jsonSchema collection validator
Middleware	Global and per-model middleware chains wrapping all operations
Population	Resolve ref= fields, including refs inside subdocuments and slices, by fetching referenced documents
Aggregation	Fluent pipeline builder with Match, Group, Sort, Lookup, and more
Bulk	CreateMany and SaveMany with hooks/validation, NewBulk builder, UpdateMany/DeleteMany passthrough
Transactions	WithTransaction wraps operations in a MongoDB session transaction
Change Streams	Watch delivers typed change events with resume tokens, filtering, and pre-images
CLI	goodm discover (introspect DB), goodm migrate (sync indexes), goodm inspect (view schemas)

How does goodm compare?

Feature	goodm	mongo-driver	mgm	mongox
Schema-as-struct tags	Yes	No	Partial	No
Lifecycle hooks	6 hooks	No	3 hooks	No
Validation (required, enum, min/max)	Yes	No	No	No
Immutable fields	Yes	No	No	No
Optimistic concurrency (versioning)	Yes	No	No	No
Population (ref resolution)	Yes	No	No	No
Aggregation builder	Fluent API	Manual	No	No
Middleware (global + per-model)	Yes	No	No	No
CLI: discover (DB → Go structs)	Yes	No	No	No
CLI: migrate (sync indexes)	Yes	No	No	No
Default values	Yes	No	No	No
Escape hatches (raw MongoDB)	Yes	N/A	Yes	Yes

Requirements

• Go 1.21+
• MongoDB 4.0+ (6.0+ recommended; tested against 6.0, 7.0, and 8.0)
• Replica set required for transactions and change streams

Release Notes

See the release notes for what changed in each version, including behavior changes to watch for when upgrading.

License

MIT