MongoDB Driver Admin Quick Tour

This is the second part of the MongoDB driver quick tour. In the quick tour we looked at how to use the Java driver to execute basic CRUD operations. In this section we’ll look at some of the administrative features available in the driver.

The following code snippets come from the QuickTourAdmin.java example code that can be found with the driver source.

Setup

To get started we’ll quickly connect and create a mongoClient, database and collection variable for use in the examples below:

MongoClient mongoClient = new MongoClient();
MongoDatabase database = mongoClient.getDatabase("mydb");
MongoCollection<Document> collection = database.getCollection("test");

Get A List of Databases

You can get a list of the available databases:

for (String name: mongoClient.listDatabaseNames()) {
    System.out.println(name);
}

Drop A Database

You can drop a database by name using a MongoClient instance:

mongoClient.getDatabase("databaseToBeDropped").drop();

Create A Collection

Collections in MongoDB are created automatically simply by inserted a document into it. Using the createCollection method, you can also create a collection explicitly in order to to customize its configuration. For example, to create a capped collection sized to 1 megabyte:

database.createCollection("cappedCollection",
  new CreateCollectionOptions().capped(true).sizeInBytes(0x100000));

Get A List of Collections

You can get a list of the available collections in a database:

for (String name : database.listCollectionNames()) {
    System.out.println(name);
}

Drop A Collection

You can drop a collection by using the drop() method:

collection.dropCollection();

Create An Index

MongoDB supports secondary indexes. To create an index, you just specify the field or combination of fields, and for each field specify the direction of the index for that field. For 1 ascending or -1 for descending. The following creates an ascending index on the i field:

// create an ascending index on the "i" field
 collection.createIndex(new Document("i", 1));

Get a List of Indexes on a Collection

Use the listIndexes() method to get a list of indexes. The following lists the indexes on the collection test:

for (final Document index : collection.listIndexes()) {
    System.out.println(index.toJson());
}

The example should print the following indexes:

{ "v" : 1, "key" : { "_id" : 1 }, "name" : "_id_", "ns" : "mydb.test" }
{ "v" : 1, "key" : { "i" : 1 }, "name" : "i_1", "ns" : "mydb.test" }

Text indexes

MongoDB also provides text indexes to support text search of string content. Text indexes can include any field whose value is a string or an array of string elements. To create a text index specify the string literal “text” in the index document:

// create a text index on the "content" field
coll.createIndex(new Document("content", "text"));

As of MongoDB 2.6, text indexes are now integrated into the main query language and enabled by default (here we use the Filters.text helper):

// Insert some documents
collection.insertOne(new Document("_id", 0).append("content", "textual content"));
collection.insertOne(new Document("_id", 1).append("content", "additional content"));
collection.insertOne(new Document("_id", 2).append("content", "irrelevant content"));

// Find using the text index
long matchCount = collection.count(Filters.text("textual content -irrelevant"));
System.out.println("Text search matches: " + matchCount);

// Find using the $language operator
Bson textSearch = Filters.text("textual content -irrelevant", "english");
matchCount = collection.count(textSearch);
System.out.println("Text search matches (english): " + matchCount);

// Find the highest scoring match
Document projection = new Document("score", new Document("$meta", "textScore"));
Document myDoc = collection.find(textSearch).projection(projection).first();
System.out.println("Highest scoring document: " + myDoc.toJson());

and it should print:

Text search matches: 2
Text search matches (english): 2
Highest scoring document: { "_id" : 1, "content" : "additional content", "score" : 0.75 }

For more information about text search see the text index and $text query operator documentation.

Running a command

Not all commands have a specific helper, however you can run any command by using the runCommand() method. Here we call the buildInfo command:

Document buildInfo = database.runCommand(new Document("buildInfo", 1));
System.out.println(buildInfo);