golobby/orm

A lightweight yet powerful, fast, customizable, type-safe object-relational mapper for the Go programming language.

Programming language: Go

License: MIT License

Tags: ORM    

README

Golobby ORM

GoLobby ORM is a lightweight yet powerful, fast, customizable, type-safe object-relational mapper for the Go programming language.

Table Of Contents

• Features
  • Introduction
  • Creating a new Entity
    • Conventions
    • Timestamps
    • Column names
    • Primary Key
  • Initializing ORM
  • Fetching an entity from a database
  • Saving entities or Insert/Update
  • Using raw SQL
  • Deleting entities
  • Relationships
    • HasMany
    • HasOne
    • BelongsTo
    • BelongsToMany
    • Saving with relation
  • Query Builder
    • Finishers
    • All
    • Get
    • Update
    • Delete
    • Select
    • Column names
    • Table
    • Where
    • Order By
    • Limit
    • Offset
    • First, Latest
    • Update
    • Where
    • Table
    • Set
    • Delete
    • Table
    • Where
  • Database Validations
• License

Introduction

GoLobby ORM is an object-relational mapper (ORM) that makes it enjoyable to interact with your database. When using Golobby ORM, each database table has a corresponding "Entity" to interact with that table using elegant APIs.

Features

• Elegant and easy-to-use APIs with the help of Generics.
• Type-safety.
• Using reflection at startup to be fast during runtime.
• No code generation!
• Query builder for various query types.
• Binding query results to entities.
• Supports different kinds of relationship/Association types:
  • One to one
  • One to Many
  • Many to Many

Quick Start

The following example demonstrates how to use the GoLobby ORM.

package main

import "github.com/golobby/orm"

// User entity
type User struct {
  ID        int64
  FirstName string
  LastName  string
  Email     string
  orm.Timestamps
}

// It will be called by ORM to setup entity.
func (u User) ConfigureEntity(e *orm.EntityConfigurator) {
    // Specify related database table for the entity.
    e.Table("users")
}

func main() {
  // Setup ORM
  err := orm.Initialize(orm.ConnectionConfig{
    // Name:          "default",  // Optional. Specify connection names if you have more than on database.
    Driver:           "sqlite3",  // Database type. Currently supported sqlite3, mysql, mariadb, postgresql. 
    ConnectionString: ":memory:", // Database DSN.
    DatabaseValidations: true,    // Validates your database tables and each table schema
  })

  if err != nil {
      panic(err)
  }

  // Find user by primary key (ID)
  user, err := orm.Find[User](1)

  // Update entity
  user.Email = "[email protected]"

  // Save entity
  orm.Save(&user)
}

Creating a new Entity

Let's create a new Entity to represent User in our application.

package main

import "github.com/golobby/orm"

type User struct {
  ID       int64
  Name     string
  LastName string
  Email    string
  orm.Timestamps
}

func (u User) ConfigureEntity(e *orm.EntityConfigurator) {
    e.Table("users").
      Connection("default") // You can omit connection name if you only have one.

}

As you see, our user entity is nothing else than a simple struct and two methods. Entities in GoLobby ORM are implementations of Entity interface, which defines two methods:

• ConfigureEntity: configures table, fields, and also relations to other entities. #### Conventions We have standard conventions and we encourage you to follow, but if you want to change them for any reason you can use Field method to customize how ORM inferres meta data from your Entity.

Column names

GoLobby ORM for each struct field(except slice, arrays, maps, and other nested structs) assumes a respective column named using snake case syntax. If you want a custom column name, you should specify it in ConfigureEntity method using Field() method.

package main

type User struct {
  Name string
}

func (u User) ConfigureEntity(e *orm.EntityConfigurator) {
    e.Field("Name").ColumnName("custom_name_for_column")

    e.Table("users")
}

Timestamps

for having created_at, updated_at, deleted_at timestamps in your entities you can embed orm.Timestamps struct in your entity,

type User struct {
  ID       int64
  Name     string
  LastName string
  Email    string
  orm.Timestamps
}

Also, if you want custom names for them, you can do it like this.

type User struct {
    ID       int64
    Name     string
    LastName string
    Email    string
    MyCreatedAt sql.NullTime
    MyUpdatedAt sql.NullTime
    MyDeletedAt sql.NullTime
}
func (u User) ConfigureEntity(e *orm.EntityConfigurator) {
    e.Field("MyCreatedAt").IsCreatedAt() // this will make ORM to use MyCreatedAt as created_at column
    e.Field("MyUpdatedAt").IsUpdatedAt() // this will make ORM to use MyUpdatedAt as created_at column
    e.Field("MyDeletedAt").IsDeletedAt() // this will make ORM to use MyDeletedAt as created_at column

    e.Table("users")
}

As always you use Field method for configuring how ORM behaves to your struct field.

Primary Key

GoLobby ORM assumes that each entity has a primary key named id; if you want a custom primary key called, you need to specify it in entity struct.

package main

type User struct {
    PK int64
}
func (u User) ConfigureEntity(e *orm.EntityConfigurator) {
    e.Field("PK").IsPrimaryKey() // this will make ORM use PK field as primary key.
    e.Table("users")
}

Initializing ORM

After creating our entities, we need to initialize GoLobby ORM.

package main

import "github.com/golobby/orm"

func main() {
  orm.Initialize(orm.ConnectionConfig{
    // Name:             "default", You should specify connection name if you have multiple connections
    Driver:           "sqlite3",
    ConnectionString: ":memory:",
  })
}

After this step, we can start using ORM.

Fetching an entity from a database

GoLobby ORM makes it trivial to fetch entities from a database using its primary key.

user, err := orm.Find[User](1)

orm.Find is a generic function that takes a generic parameter that specifies the type of Entity we want to query and its primary key value. You can also use custom queries to get entities from the database.

user, err := orm.Query[User]().Where("id", 1).First()
user, err := orm.Query[User]().WherePK(1).First()

GoLobby ORM contains a powerful query builder, which you can use to build Select, Update, and Delete queries, but if you want to write a raw SQL query, you can.

users, err := orm.QueryRaw[User](`SELECT * FROM users`)

Saving entities or Insert/Update

GoLobby ORM makes it easy to persist an Entity to the database using Save method, it's an UPSERT method, if the primary key field is not zero inside the entity it will go for an update query; otherwise, it goes for the insert.

// this will insert entity into the table
err := orm.Save(&User{Name: "Amirreza"}) // INSERT INTO users (name) VALUES (?) , "Amirreza"

// this will update entity with id = 1
orm.Save(&User{ID: 1, Name: "Amirreza2"}) // UPDATE users SET name=? WHERE id=?, "Amirreza2", 1

Also, you can do custom update queries using query builder or raw SQL again as well.

res, err := orm.Query[User]().Where("id", 1).Update(orm.KV{"name": "amirreza2"})

Using raw SQL

_, affected, err := orm.ExecRaw[User](`UPDATE users SET name=? WHERE id=?`, "amirreza", 1)

Deleting entities

It is also easy to delete entities from a database.

err := orm.Delete(user)

You can also use query builder or raw SQL.

_, affected, err := orm.Query[Post]().WherePK(1).Delete()

_, affected, err := orm.Query[Post]().Where("id", 1).Delete()

_, affected, err := orm.ExecRaw[Post](`DELETE FROM posts WHERE id=?`, 1)

Relationships

GoLobby ORM makes it easy to have entities that have relationships with each other. Configuring relations is using ConfigureEntity method, as you will see.

HasMany

type Post struct {}

func (p Post) ConfigureEntity(e *orm.EntityConfigurator) {
    e.Table("posts").HasMany(&Comment{}, orm.HasManyConfig{})
}

As you can see, we are defining a Post entity that has a HasMany relation with Comment. You can configure how GoLobby ORM queries HasMany relation with orm.HasManyConfig object; by default, it will infer all fields for you. Now you can use this relationship anywhere in your code.

comments, err := orm.HasMany[Comment](post).All()

HasMany and other related functions in GoLobby ORM return QueryBuilder, and you can use them like other query builders and create even more complex queries for relationships. for example, you can start a query to get all comments of a post made today.

todayComments, err := orm.HasMany[Comment](post).Where("created_at", "CURDATE()").All()

HasOne

Configuring a HasOne relation is like HasMany.

type Post struct {}

func (p Post) ConfigureEntity(e *orm.EntityConfigurator) {
    e.Table("posts").HasOne(&HeaderPicture{}, orm.HasOneConfig{})
}

As you can see, we are defining a Post entity that has a HasOne relation with HeaderPicture. You can configure how GoLobby ORM queries HasOne relation with orm.HasOneConfig object; by default, it will infer all fields for you. Now you can use this relationship anywhere in your code.

picture, err := orm.HasOne[HeaderPicture](post)

HasOne also returns a query builder, and you can create more complex queries for relations.

BelongsTo

type Comment struct {}

func (c Comment) ConfigureEntity(e *orm.EntityConfigurator) {
    e.Table("comments").BelongsTo(&Post{}, orm.BelongsToConfig{})
}

As you can see, we are defining a Comment entity that has a BelongsTo relation with Post that we saw earlier. You can configure how GoLobby ORM queries BelongsTo relation with orm.BelongsToConfig object; by default, it will infer all fields for you. Now you can use this relationship anywhere in your code.

post, err := orm.BelongsTo[Post](comment).First()

BelongsToMany

type Post struct {}

func (p Post) ConfigureEntity(e *orm.EntityConfigurator) {
    e.Table("posts").BelongsToMany(&Category{}, orm.BelongsToManyConfig{IntermediateTable: "post_categories"})
}

type Category struct{}

func(c Category) ConfigureEntity(r *orm.EntityConfigurator) {
    e.Table("categories").BelongsToMany(&Post{}, orm.BelongsToManyConfig{IntermediateTable: "post_categories"})
}

We are defining a Post entity and a Category entity with a many2many relationship; as you can see, we must configure the IntermediateTable name, which GoLobby ORM cannot infer. Now you can use this relationship anywhere in your code.

categories, err := orm.BelongsToMany[Category](post).All()

Saving with relation

You may need to save an entity that has some kind of relationship with another entity; in that case, you can use Add method.

orm.Add(post, comments...) // inserts all comments passed in and also sets all post_id to the primary key of the given post.

Query Builder

GoLobby ORM contains a powerful query builder to help you build complex queries with ease. QueryBuilder is accessible from orm.Query[Entity] method which will create a new query builder for you with given type parameter. Query builder can build SELECT,UPDATE,DELETE queries for you.

Finishers

Finishers are methods on QueryBuilder that will some how touch database, so use them with caution.

All

All will generate a SELECT query from QueryBuilder, execute it on database and return results in a slice of OUTPUT. It's useful for queries that have multiple results.

posts, err := orm.Query[Post]().All() 

Get

Get will generate a SELECT query from QueryBuilder, execute it on database and return results in an instance of type parameter OUTPUT. It's useful for when you know your query has single result.

post, err := orm.Query[Post]().First().Get()

Update

Update will generate an UPDATE query from QueryBuilder and executes it, returns rows affected by query and any possible error.

rowsAffected, err := orm.Query[Post]().WherePK(1).Set("body", "body jadid").Update()

Delete

Delete will generate a DELETE query from QueryBuilder and executes it, returns rows affected by query and any possible error.

rowsAffected, err := orm.Query[Post]().WherePK(1).Delete()

Select

Let's start with Select queries. Each Select query consists of following:

SELECT [column names] FROM [table name] WHERE [cond1 AND/OR cond2 AND/OR ...] ORDER BY [column] [ASC/DESC] LIMIT [N] OFFSET [N] GROUP BY [col]

Query builder has methods for constructing each part, of course not all of these parts are necessary.

Column names

for setting column names to select use Select method as following:

orm.Query[Post]().Select("id", "title")

Table

for setting table name for select use Table method as following:

orm.Query[Post]().Table("users")

Where

for adding where conditions based on what kind of where you want you can use any of following:

orm.Query[Post]().Where("name", "amirreza") // Equal mode: WHERE name = ?, ["amirreza"]
orm.Query[Post]().Where("age", "<", 19) // Operator mode: WHERE age < ?, [19]
orm.Query[Post]().WhereIn("id", 1,2,3,4,5) // WhereIn: WHERE id IN (?,?,?,?,?), [1,2,3,4,5]

You can also chain these together.

orm.Query[Post]().
    Where("name", "amirreza").
    AndWhere("age", "<", 10).
    OrWhere("id", "!=", 1)
    // WHERE name = ? AND age < ? OR id != ?, ["amirreza", 10, 1]

Order By

You can set order by of query using OrderBy as following.

orm.Query[Post]().OrderBy("id", orm.ASC) // ORDER BY id ASC
orm.Query[Post]().OrderBy("id", orm.DESC) // ORDER BY id DESC

Limit

You can set limit setting of query using Limit as following

orm.Query[Post]().Limit1(1) // LIMIT 1

Offset

You can set limit setting of query using Offset as following

orm.Query[Post]().Offset(1) // OFFSET 1

First, Latest

You can use First, Latest method which are also executers of query as you already seen to get first or latest record.

orm.Query[Post]().First() // SELECT * FROM posts ORDER BY id ASC LIMIT 1
orm.Query[Post]().Latest() // SELECT * FROM posts ORDER BY id DESC LIMIT 1

Update

Each Update query consists of following:

UPDATE [table name] SET [col=val] WHERE [cond1 AND/OR cond2 AND/OR ...]

Where

Just like select where stuff, same code.

Table

Same as select.

Set

You can use Set method to set value.

orm.Query[Message]().
  Where("id", 1).
  Set("read", true, "seen", true).
  Update() // UPDATE posts SET read=?, seen=? WHERE id = ?, [true, true, 1]

Delete

Each Delete query consists of following:

DELETE FROM [table name] WHERE [cond1 AND/OR cond2 AND/OR ...]

Table

Same as Select and Update.

Where

Same as Select and Update.

Database Validations

Golobby ORM can validate your database state and compare it to your entities and if your database and code are not in sync give you error. Currently there are two database validations possible:

1. Validate all necessary tables exists.
2. Validate all tables contain necessary columns. You can enable database validations feature by enabling DatabaseValidations flag in your ConnectionConfig. go return orm.SetupConnections(orm.ConnectionConfig{ Name: "default", DB: db, Dialect: orm.Dialects.SQLite3, Entities: []orm.Entity{&Post{}, &Comment{}, &Category{}, &HeaderPicture{}}, DatabaseValidations: true, }) ## License GoLobby ORM is released under the MIT License.