Getting Started with Bolt: A Guide to Key-Value Storage in Go

Bolt is a lightweight, embedded key-value store written in Go. It is designed to be simple and fast, making it an ideal choice for projects that need a embedded database without the overhead of a more feature-rich database like PostgreSQL or MySQL.

To use Bolt in a Go project, you will need to install the library using the go get command:

        
    go get github.com/boltdb/bolt
        

Once the library is installed, you can import it into your Go code using the following import statement:

        
    import "github.com/boltdb/bolt"
    

To open a Bolt database, you can use the Open function:

        
    db, err := bolt.Open("my.db", 0600,nil)

    if err != nil {
    
        // handle error

    }

    defer db.Close()

        

This will open the database file my.db in read-write mode with the specified file permissions (0600 in this example, which means that the file is readable and writable only by the owner).

To store a key-value pair in the database, you can use the Put function:

        
    err = db.Update(func(tx *bolt.Tx) error {
    bucket,
    err := tx.CreateBucketIfNotExists([]byte("mybucket"))
    if err != nil
    {
        return err
    }
    err =  bucket.Put([]byte("mykey"), []byte("myvalue"))
    if err != nil
    {
        return err
    }
   
    return nil
})

        

This will create a new bucket called "mybucket" if it does not already exist, and then store the key-value pair "mykey"-"myvalue" in the bucket.

To retrieve a value for a given key, you can use the Get function:

        
    var value []byte
err = db.View(func(tx *bolt.Tx) error {
   
    bucket := tx.Bucket([]byte("mybucket"))
    if bucket == nil
    {
        return fmt.Errorf("Bucket not found")
   
    }
    value = bucket.Get([]byte("mykey"))
    return nil
})

        

This will retrieve the value for the key "mykey" from the "mybucket" bucket. If the key does not exist, the Get function will return a nil slice.

 
package main

import (
	"fmt"
	"log"

	"github.com/boltdb/bolt"
)

func main() {
	// Open a Bolt database file.
	db, err := bolt.Open("my.db", 0600, nil)
	if err != nil {
		log.Fatal(err)
	}
	defer db.Close()

	// Use an update function to store a key-value pair in the database.
	err = db.Update(func(tx *bolt.Tx) error {
		bucket, err := tx.CreateBucketIfNotExists([]byte("mybucket"))
		if err != nil {
			return err
		}
		err = bucket.Put([]byte("mykey"), []byte("myvalue"))
		if err != nil {
			return err
		}
		return nil
	})
	if err != nil {
		log.Fatal(err)
	}

	// Use a view function to retrieve the value for the key.
	var value []byte
	err = db.View(func(tx *bolt.Tx) error {
		bucket := tx.Bucket([]byte("mybucket"))
		if bucket == nil {
			return fmt.Errorf("Bucket not found")
		}
		value = bucket.Get([]byte("mykey"))
		return nil
	})
	if err != nil {
		log.Fatal(err)
	}

	// Print the retrieved value.
	fmt.Println(string(value))
}