hare

README

Hare - A nimble little database management system written in Go

Hare is a pure Go database management system that stores each table as a text file of line-delimited JSON. Each line of JSON represents a record. It is a good fit for applications that require a simple embedded DBMS.

Table of Contents

• Getting Started
  • Installing
  • Usage
• Features
• Example Web App

Getting Started

Installing

To start using Hare, install Go and run go get:

$ go get github.com/jameycribbs/hare

Usage

Setting up Hare to use your JSON file(s)

Each JSON file is represented by a hare.Table. To set things up, you need to create a struct with an embedded pointer to a hare.Table and add a Query method to it.

Additionally, you need to create a struct for a table's record, with it's members cooresponding to the JSON field names, and implement 3 simple boilerplate methods on that struct that allow it to satisfy the hare.Record interface.

A good way to structure this is to put this boilerplate code in a "models" package in your project. You can find an example of this boilerplate code in the examples/crud/models/episodes.go file.

Now you are ready to go!

Let's say you have a "data" directory with a file in it called "contacts.json".

The top-level object in Hare is a Database. It represents the directory on your disk where the JSON files are located.

To open your database, simply use the hare.OpenDB function:

// OpenDB takes a directory path containing zero or more JSON files and returns
// a database connection.
db, err := hare.OpenDB("data")

defer db.Close()
...

Now, grab a reference to the hare.Table for the JSON file and store it in your model:

var contacts models.Contacts

contacts.Table, err = db.GetTable("contacts")

Creating a record

To add a record, you can use the Create method:

recID, err := contacts.Create(&models.Contact{FirstName: "John", LastName: "Doe", Phone: "888-888-8888", Age: 21})

Finding a record

To find a record if you know the record ID, you can use the Find method:

var c models.Contact

err = contacts.Find(1, &c)

Updating a record

To update a record, you can use the Update method:

c.Age = 22

err = contacts.Update(&c)

Deleting a record

To delete a record, you can use the Destroy method:

err = contacts.Destroy(3)

Querying a table

To query the database, you can write your query expression in pure Go and pass it to your model's Query method as a closure.

results, err := contacts.Query(func(c models.Contact) bool {
  return c.firstname == "John" && c.lastname == "Doe"
}, 0)

Database Administration

There are also built-in methods you can run against the database to create a new table or delete an existing table.

Features

• Records for each table are stored in a newline-delimited JSON file.

• Mutexes are used for table locking. You can have multiple readers or one writer for that table at one time, as long as all processes share the same Database connection.

• Querying is done using Go itself. No need to use a DSL.

• The database is not read into memory, but is queried from disk, so no need to worry about a large dataset filling up memory.

• Two different back-end datastores to choose from: disk or ram.

Example Web App

SnippetBox using Hare This is a version of the SnippetBox web application featured in Alex Edward's outstanding book, Let's Go, with Hare replacing MySQL as the DBMS. This is just a demonstration, mainly to show how you could use Hare in a web application.

Documentation

Overview

Package hare implements a simple DBMS that stores it's data in newline-delimited json files.

Index

• Variables
• type Database
  • func New(ds datastorage) (*Database, error)
  • func (db *Database) Close() error
  • func (db *Database) CreateTable(tableName string) error
  • func (db *Database) Delete(tableName string, id int) error
  • func (db *Database) DropTable(tableName string) error
  • func (db *Database) Find(tableName string, id int, rec Record) error
  • func (db *Database) IDs(tableName string) ([]int, error)
  • func (db *Database) Insert(tableName string, rec Record) (int, error)
  • func (db *Database) TableExists(tableName string) bool
  • func (db *Database) Update(tableName string, rec Record) error
• type Record

Variables

var (
	ErrNoTable     = errors.New("hare: no table with that name found")
	ErrTableExists = errors.New("hare: table with that name already exists")
)

Types

type Database

type Database struct {
	// contains filtered or unexported fields
}

func New

func New(ds datastorage) (*Database, error)

func (*Database) Close

func (db *Database) Close() error

func (*Database) CreateTable

func (db *Database) CreateTable(tableName string) error

func (*Database) Delete

func (db *Database) Delete(tableName string, id int) error

func (*Database) DropTable

func (db *Database) DropTable(tableName string) error

func (*Database) Find

func (db *Database) Find(tableName string, id int, rec Record) error

func (*Database) IDs

func (db *Database) IDs(tableName string) ([]int, error)

func (*Database) Insert

func (db *Database) Insert(tableName string, rec Record) (int, error)

func (*Database) TableExists

func (db *Database) TableExists(tableName string) bool

TableExists takes a table name and returns true if the table exists, false if it does not.

func (*Database) Update

func (db *Database) Update(tableName string, rec Record) error

type Record

type Record interface {
	SetID(int)
	GetID() int
	AfterFind()
}