activemodel

activemodel — go-ruby-activemodel

A pure-Go (no cgo) reimplementation of Ruby on Rails' ActiveModel — the model-behaviour toolkit that gives a plain object validations, an errors collection, and conventional naming. This v0.1 foundation mirrors the observable behaviour of the activemodel gem on MRI 4.0.5, without any Ruby runtime.

It is the ActiveModel backend for go-embedded-ruby, but is a standalone, reusable module — a sibling of go-ruby-activesupport (whose Inflector it reuses for naming) and go-ruby-set.

v0.1 scope — the Validations + Errors + Naming core

The seams — reaching a model without open classes

Go has no open classes, so the object under validation is reached through two small interfaces (combined as Model), which a host such as go-embedded-ruby plugs its own object behind:

// Attribute get/set — Ruby attr readers/writers and read_attribute_for_validation.
type Attr interface {
	Get(name string) any
	Set(name string, val any)
}

// Method-call seam — a symbol if:/unless: condition, and the respond_to? guard.
type Dispatcher interface {
	Call(method string) any
	RespondTo(method string) bool
}

type Model interface { Attr; Dispatcher }

Everything the validators need is expressed through these: presence reads the attribute (Get); confirmation reads #{attr}_confirmation (Get); a symbol if: condition calls a method (Call); the %{value} interpolation honours the respond_to? guard (RespondTo). Custom validate bodies and proc conditions are plain Go funcs — the seam for the Ruby block.

Install

go get github.com/go-ruby-activemodel/activemodel

Usage

package main

import (
	"fmt"
	"regexp"

	am "github.com/go-ruby-activemodel/activemodel"
)

func main() {
	v := am.New(am.NewName("Person"))
	v.Validates([]string{"name"}, am.Options{Presence: true})
	v.Validates([]string{"email"}, am.Options{
		Format:     &am.FormatOptions{With: regexp.MustCompile(`@`)},
		AllowBlank: true,
	})
	v.Validates([]string{"age"}, am.Options{
		Numericality: &am.NumericalityOptions{OnlyInteger: true, GreaterThan: 0},
	})

	person := /* your Model seam */ nil
	if ok, errs := v.Valid(person); !ok {
		for _, m := range errs.FullMessages() {
			fmt.Println(m) // e.g. "Name can't be blank"
		}
	}

	n := am.NewName("Admin::User")
	fmt.Println(n.Plural, n.RouteKey, n.Human) // admin_users admin_users User
}

Fidelity — the MRI oracle

The suite pairs deterministic, ruby-free tests (which alone hold coverage at 100%, so the qemu cross-arch and Windows lanes pass the gate) with a differential ActiveModel oracle: model_name fields and full_messages across the whole validator matrix are computed here and diffed against the real activemodel gem running on the system ruby. CI installs the gem on the ubuntu/macos lanes; the oracle skips itself where ruby or the gem is absent.

Roadmap — the deferred ActiveModel subsystems

v0.1 is the model-description core. Still to come, in rough priority order:

• Attributes — the typecasting system (attribute :born_on, :date), with the type registry and default/coercion behaviour.
• Dirty — change tracking (changed?, *_was, changes, saved_changes).
• Callbacks — before_validation / after_validation (and the general ActiveModel::Callbacks define/run machinery) — surfaced as an ordering seam around Valid.
• Serialization — serializable_hash, to_json / from_json, to_xml.
• SecurePassword — has_secure_password, later reusing go-ruby-bcrypt.
• Translation / I18n — full errors.messages / activemodel.models lookup chains, locale fallbacks and pluralization backends (v0.1 ships the English default table and count-based length pluralization).

Tests & coverage

COVERPKG=$(go list ./... | paste -sd, -)
go test -race -coverpkg="$COVERPKG" -coverprofile=cover.out ./...
go tool cover -func=cover.out | tail -1   # 100.0%

CGO-free, gofmt + go vet clean, and green across the six 64-bit Go targets (amd64, arm64, riscv64, loong64, ppc64le, s390x) and three OSes (Linux, macOS, Windows). The one dependency is the pure-Go go-ruby-activesupport (Inflector).

License

BSD-3-Clause — see LICENSE. Copyright the go-ruby-activemodel/activemodel authors.

WebAssembly

Being pure Go (CGO=0), this library also compiles to WebAssembly — both GOOS=js GOARCH=wasm (browser / Node.js) and GOOS=wasip1 GOARCH=wasm (WASI). CI builds both targets on every push, alongside the six 64-bit native/qemu arches.

GOOS=js     GOARCH=wasm go build ./...   # browser / Node
GOOS=wasip1 GOARCH=wasm go build ./...   # WASI (wasmtime, wasmer, wasmedge, …)