azer / Crud

CRUD

A minimalistic relational database library for Go.

Features:

• Fast.
• Well tested.
• Being used in production since 2015.
• Internal logging with timers, can be configured for streaming slow queries into Slack.

Manual:

Table of Contents

• Install
• Initialize
• Define
  • Reset Tables
  • SQL Options
  • Create
  • CreateAndRead
  • Read
    • Reading multiple rows:
    • Scanning to custom values:
  • Update
  • Delete
  • Transactions
  • Logs
  • Custom Queries
  • Why another ORMish library for Go?
  • Apps Using CRUD
  • What's Missing?
  • LICENSE

Install

$ go get github.com/azer/crud

Initialize

import (
  "github.com/azer/crud"
  _ "github.com/go-sql-driver/mysql"
)

var DB *crud.DB

func init () {
  var err error
  DB, err = crud.Connect("mysql", os.Getenv("DATABASE_URL"))
  err = DB.Ping()
}

Define

type User struct {
  Id int `sql:"auto-increment primary-key"`
  FirstName string
  LastName string
  ProfileId int
}

type Profile struct {
  Id int `sql:"auto-increment primary-key"`
  Bio string `sql:"text"`
}

CRUD will automatically convert column names from "FirstName" (CamelCase) to "first_name" (snake_case) for you. You can still choose custom names though;

type Post struct {
  Slug string `sql:"name=slug_id varchar(255) primary-key required"`
}

If no primary key is specified, CRUD will look for a field named "Id" with int type, and set it as auto-incrementing primary-key field.

Create & Drop Tables

CreateTables takes list of structs and makes sure they exist in the database.

err := DB.CreateTables(User{}, Profile{})

err := DB.DropTables(User{}, Profile{})

Reset Tables

Shortcut for dropping and creating tables.

err := DB.ResetTables(User{}, Profile{})

SQL Options

CRUD tries to be smart about figuring out the best SQL options for your structs, and lets you choose manually, too. For example;

type Tweet struct {
 Text string `sql:"varchar(140) required name=tweet"`
}

Above example sets the type of the Text column as varchar(140), makes it required (NOT NULL) and changes the column name as tweet.

Here is the list of the options that you can pass;

• Types: int, bigint, varchar, text, date, time, timestamp
• auto-increment / autoincrement / auto_increment
• primary-key / primarykey / primary_key
• required
• default='?'
• name=?
• table-name=?

If you'd like a struct field to be ignored by CRUD, choose - as options:

type Foo struct {
 IgnoreMe string `sql:"-"`
}

Create

Simply pass a struct. It can be pointer or not.

user := &User{1, "Foo", "Bar", 1}
err := DB.Create(user)

CreateAndRead

Create a row, and read it back from the DB. The values of the struct you passed get resetted to whatever the corresponding DB row has. In the other words, CreateAndRead creates, and reads. So you got fields generated by the DB scanned to your struct, like ID.

Make sure passing a pointer.

user := User{
  FirstName:"Foo"
}

err := DB.CreateAndRead(&user)

user.Id
// => 123

Read

You can read single/multiple rows, or custom values, with the Read method.

Reading a single row:

Pass your struct's pointer, and a query;

user := &User{}
err := DB.Read(user, "SELECT * FROM users WHERE id = ?", 1)
// => SELECT * FROM users WHERE id = 1

fmt.Println(user.Name)
// => Foo

Reading multiple rows:

users := []*User{}

err := DB.Read(&users)
// => SELECT * FROM users

fmt.Println(len(users))
// => 10

Scanning to custom values:

names := []string{}
err := DB.Read(&names, "SELECT name FROM users")

name := ""
err := DB.Read(&name, "SELECT name FROM users WHERE id=1")

totalUsers := 0
err := DB.Read(&totalUsers, "SELECT COUNT(id) FROM users"

Update

Updates matching row in database, returns sql.ErrNoRows nothing matched.

user := &User{}
err := DB.Read(user, "SELECT * FROM users WHERE id = ?", 1)

user.Name = "Yolo"
err := DB.Update(user)

Delete

Deletes matching row in database, returns sql.ErrNoRows nothing matched.

err := DB.Delete(&User{
  Id: 1
})

Transactions

Use Begin method of a crud.DB instance to create a new transaction. Each transaction will provide you following methods;

• Commit
• Rollback
• Exec
• Query
• Create
• Read
• Update
• Delete

tx, err := DB.Begin()

err := tx.Create(&User{
  Name: "yolo"
})

err := tx.Delete(&User{
  Id: 123
})

err := tx.Commit()

Logs

If you want to see crud's internal logs, specify crud in the LOG environment variable when you run your app. For example;

$ LOG=crud go run myapp.go

(More info about how crud's logging work)

Custom Queries

result, err := DB.Query("DROP DATABASE yolo") // or .Exec

Running Tests

DATABASE_URL="?" go test ./...

Why another ORMish library for Go?

• Simplicity, taking more advantage of reflect library to keep the API simple.
• Building less things with more complete abstractions
• Handling errors in an idiomatic way
• Good test coverage
• Modular & reusable code
• Making less unsafe assumptions. e.g: not mapping structs to SQL rows by column index.
• Complete & tested SQL Options

Apps Using CRUD

• Kozmos
• MultiplayerChess.com
• Listen Paradise.

What's Missing?

• Migration: We need a sophisticated solution for adding / removing columns when user changes the structs.
• Relationships: This was intentionally avoided. Can be considered if there is a clean way to implement it.
• Testing Transactions: Transactions work as expected but there is a sync bug in the test causing failure. It needs to be fixed.
• Comments: I rarely comment my code.
• Hooks: I'm not sure if this is needed, but worths to consider.
• Foreign Keys: *
• Query Builder: Building SQL queries programmatically is useful.
• Make UTF-8 Default: Looks like the default charset is not UTF8.

LICENSE

WTFPL