Update

Insert

Inserting new documents into a collection is done with the insert command.

This can be done from the mongo command shell.

The following command inserts a new entry in our “movies” collection in the “entertainment” database.

mongo entertainment

db.movies.insert(
      {
        title: "The Matrix",
        year: 1999,
        directors: [ "Andy Wachowski", "Lana Wachowski" ],
        writers: [ "Andy Wachowski", "Lana Wachowski" ],
        stars: [ "Keanu Reeves", "Laurence Fishburne", "Carrie-Anne Moss"]
      }
    )

To see the effect of the insertion we can query the new entry by using the find command:

db.movies.find( { title: "The Matrix" } )

You will see something similar to the following screen:

Update

Modification to existing documents can be made with the update command.

The update command has two parts:

• The first one selects the documents to be modified, similar to the find command.
• The second indicates the fields that will be modified along their new values.

For example

db.movies.update(
     { title: "The Matrix" },
     { $set : { year: 2000 } }
  )

Here we are selecting the documents corresponding to movies whose title matches “The Matrix”, and then we are replacing their “year” field with the value “2000”.

Notice the use of the $set operator in the second part of the update command.

This operator specifies how the field is to be modified in this update.

To see the effect of the change we use again the find command:

db.movies.find( { title: "The Matrix" } )

Notice how the value of the “year” field has changed after we use the update command.

Exercise

• Go to the Movie Database IMDB
• Find three of your favorite movies
• Insert them as documents in the movies collection using the insert command.* Review them with the find command.
• Correct any errors with the update command.

As you do, you may find that there are duplicates in the database, since some of your peers may have selected the same movies as their favorites and during the process of insertion MongoDB considers each one of them to be an independent document.

Command Line

In addition to creating entries from the interactive MongoDB interpreter shell, we can also use Javascript files as the mechanism for entering data in a mongo database.

Let write the following in a file called “insertOneMovie.js”:

db.movies.insert(
{
  title: "The Matrix",
  year: 1999,
  directors: [ "Andy Wachowski", "Lana Wachowski" ],
  writers: [ "Andy Wachowski", "Lana Wachowski" ],
  stars: [ "Keanu Reeves", "Laurence Fishburne", "Carrie-Anne Moss"]
}
)

Then, we can perform the actual entry insertion with the following command

mongo  entertainment  ./insertOneMovie.js

Where the first argument “entertainment” is the name of our database.

If we are working in a remote machine, we could write the script locally using our favorite text editor, and then we can copy our insertOneMovie.js file, to the server by using the command:

scp  insertOneMovie.js  username@hostname:

Where:

• “username” should be your actual username in that server
• “hostname” should be your actual name of that server
• Note the use of the colon symbol ”:” at the end of the server name

Finally, we can then use the command in the server:

mongo  entertainment  ./insertOneMovie.js

Exercise

Use this mechanism to enter two more of your favorite movies from the IMDB database.

More Examples

Here are a few more examples

The Matrix Reloaded

{
  title: "The Matrix Reloaded",
  year: 2003,
  directors: [ "Andy Wachowski", "Lana Wachowski" ],
  writers: [ "Andy Wachowski", "Lana Wachowski" ],
  stars: [ "Keanu Reeves", "Laurence Fishburne", "Carrie-Anne Moss"]
}

The Matrix Revolutions

{
  title: "The Matrix Revolutions",
  year: 2003,
  directors: [ "Andy Wachowski", "Lana Wachowski" ],
  writers: [ "Andy Wachowski", "Lana Wachowski" ],
  stars: [ "Keanu Reeves", "Laurence Fishburne", "Carrie-Anne Moss"]
}

Freedom Writers

{
  title: "Freedom Writers",
  year: 2007,
  director: "Richard LaGravanase",
  writers: [ "Richard LaGravenese", { book : [ "Zlata Filpovic", "Erin Gruwell" ] } ],
  stars: [ "Hilary Swank", "Imelda Stauton", "Patrick Dempsey" ]
}

You will find more examples in the following directory:

https://github.com/luisibanez/open-source-databases-tutorial/tree/master/source/MongoDB/JSON