Go Revision Library

A Go library for tracking and comparing struct revisions. It provides a simple interface to detect changes between two struct instances, with support for field inclusion/exclusion and easy integration into your projects.

Features

• Compare two structs and get a list of changed fields
• Ignore unexported fields automatically
• Include or exclude specific fields from comparison
• Simple API for checking if structs are identical or changed

Installation

go get github.com/go-universal/revision

Usage

Basic Example

package main

import (
    "fmt"
    "github.com/go-universal/revision"
)

type User struct {
    ID    int
    Name  string
    Email string
    age   int // unexported, will be ignored
}

func main() {
    oldUser := User{ID: 1, Name: "Alice", Email: "alice@example.com", age: 30}
    newUser := User{ID: 1, Name: "Alice Smith", Email: "alice.smith@example.com", age: 31}

    rev := revision.NewRevision(oldUser, newUser)

    if !rev.IsValid() {
        panic("Invalid revision: structs must be of the same type")
    }

    changes := rev.Changes()
    for _, c := range changes {
        fmt.Printf("Field: %s, Old: %v, New: %v\n", c.Field, c.OldValue, c.NewValue)
    }

    fmt.Println("IsSame:", rev.IsSame())     // false
    fmt.Println("IsChanged:", rev.IsChanged()) // true
}

Including or Excluding Fields

You can specify which fields to include or exclude in the comparison:

rev := revision.NewRevision(
    oldUser,
    newUser,
    revision.WithIncludeFields("Name"), // Only compare the Name field
)

// Or exclude specific fields
rev = revision.NewRevision(
    oldUser,
    newUser,
    revision.WithExcludeFields("Email"), // Compare all except Email
)

API

Revision Interface

• IsValid() bool — Returns true if both structs are valid and of the same type.
• Changes() Changes — Returns a slice of changed fields (see below).
• IsSame() bool — Returns true if there are no changes.
• IsChanged() bool — Returns true if there are any changes.

Change Struct

• Field string — The name of the changed field
• OldValue any — The old value
• NewValue any — The new value

Changes Methods

• Contains(field string) bool — Returns true if the field is in the changes
• Find(field string) (any, any, bool) — Returns old/new values and true if found
• Length() int — Number of changed fields
• Fields() []string — List of changed field names

License

This project is licensed under the ISC License. See the LICENSE file for details.