MongoDB

The mongo adapter for MongoDB wraps the labix.org/v2/mgo driver written by Gustavo Niemeyer.

Please note that MongoDB:

• Does not support transactions.
• Does not support query builder.
• Uses bson tags instead of db for mapping.

Installation

To use the package, you'll need the bazaar version control system:

sudo apt-get install bzr -y

Once this requirement is met, use go get to download and install the adapter:

go get github.com/upper/db/v4/adapter/mongo

Setup

Import the github.com/upper/db/v4/adapter/mongo package into your application:

// main.go
package main

import (
  "github.com/upper/db/v4/adapter/mongo"
)

Define the mongo.ConnectionURL{} struct:

// ConnectionURL defines the DSN attributes.
type ConnectionURL struct {
  User     string
  Password string
  Host     string
  Database string
  Options  map[string]string
}

Pass the mongo.ConnectionURL value as argument to mongo.Open() so the mongo.Database session is created.

settings = mongo.ConnectionURL{
  ...
}

sess, err = mongo.Open(settings)
...

The mongo.ParseURL() function is also provided in case you need to convert a DSN into a mongo.ConnectionURL:

// ParseURL parses s into a ConnectionURL struct.
mongo.ParseURL(s string) (ConnectionURL, error)

Once the connection is established, you can start performing operations on the database.

Example

In the following example, a table named 'birthday' consisting of two columns ('name' and 'born') will be created. Before starting, the table will be searched in the database and, in the event it already exists, it will be removed. Then, three rows will be inserted into the table and checked for accuracy. To this end, the database will be queried and the matches (insertions) will be printed to standard output.

The rows are inserted into the birthday table. The database is queried for the insertions and is set to print them to standard output.

// example.go

package main

import (
  "fmt"
  "log"
  "time"

  "github.com/upper/db/v4/adapter/mongo"
)

var settings = mongo.ConnectionURL{
  Database:  `upperio_tests`,  // Database name
  Host:      `127.0.0.1`,      // Server IP or name
}

type Birthday struct {
  // The 'name' column of the 'birthday' table
  // is mapped to the 'name' property.
  Name string `bson:"name"`
  // The 'born' column of the 'birthday' table
  // is mapped to the 'born' property.
  Born time.Time `bson:"born"`
}

func main() {

  // The database connection is attempted.
  sess, err := mongo.Open(settings)
  if err != nil {
    log.Fatalf("db.Open(): %q\n", err)
  }
  defer sess.Close() // Closing the session is a good practice.

  // The 'birthday' table is referenced.
  birthdayCollection := sess.Collection("birthday")

  // Any rows that might have been added between the creation of
  // the table and the execution of this function are removed.
  err = birthdayCollection.Truncate()
  if err != nil {
    log.Fatalf("Truncate(): %q\n", err)
  }

  // Three rows are inserted into the 'Birthday' table.
  birthdayCollection.Insert(Birthday{
    Name: "Hayao Miyazaki",
    Born: time.Date(1941, time.January, 5, 0, 0, 0, 0, time.Local),
  })

  birthdayCollection.Insert(Birthday{
    Name: "Nobuo Uematsu",
    Born: time.Date(1959, time.March, 21, 0, 0, 0, 0, time.Local),
  })

  birthdayCollection.Insert(Birthday{
    Name: "Hironobu Sakaguchi",
    Born: time.Date(1962, time.November, 25, 0, 0, 0, 0, time.Local),
  })

  // The database is queried for the rows inserted.
  res := birthdayCollection.Find()

  // The 'birthdays' variable is filled with the results found.
  var birthday []Birthday

  err = res.All(&birthday)
  if err != nil {
    log.Fatalf("res.All(): %q\n", err)
  }

  // The 'birthdays' variable is printed to stdout.
  for _, birthday := range birthday {
    fmt.Printf(
      "%s was born in %s.\n",
      birthday.Name,
      birthday.Born.Format("January 2, 2006"),
    )
  }
}

Compile and run the example:

go run example.go

The output will be:

Hayao Miyazaki was born in January 5, 1941.
Nobuo Uematsu was born in March 21, 1959.
Hironobu Sakaguchi was born in November 25, 1962.

Take the tour

Get the real upper/db experience, take the tour.