- Getting Started
- Admin Quick Tour
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 MongoDB Scala 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.scala
example code
that can be found with the driver source.
Note
See the installation guide for instructions on how to install the MongoDB Driver.
This guide uses the Helper
implicits as covered in the Quick Tour Primer.
Setup
To get started we’ll quickly connect and create a mongoClient
, database
and collection
variable for use in the examples below:
val mongoClient: MongoClient = MongoClient()
val database: MongoDatabase = mongoClient.getDatabase("mydb")
val collection: MongoCollection[Document] = database.getCollection("test")
Note
Calling the getDatabase()
on MongoClient
does not create a database.
Only when a database is written to will a database be created. Examples include the creation of an index or the insertion of a document
into a previously non-existent collection.
Get A List of Databases
You can get a list of the available databases by calling the listDatabaseNames
method. Here we use the implicit
printResults
helper so that we can print the list of database names:
mongoClient.listDatabaseNames().printResults()
Drop A Database
You can drop a database by name using a MongoClient
instance. Here we block for the Observable
to complete before continuing.
mongoClient.getDatabase("databaseToBeDropped").drop().headResult()
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 customize its configuration. For example, to create a capped collection sized to 1 megabyte:
database.createCollection("cappedCollection",
CreateCollectionOptions().capped(true).sizeInBytes(0x100000)
).printHeadResult("Collection Created! ")
Get A List of Collections
You can get a list of the available collections in a database:
database.listCollectionNames().printResults("Collection Names: ")
Drop A Collection
You can drop a collection by using the drop() method:
collection.drop().headResult()
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.
We can use the Indexes
helpers to create index keys:
collection.createIndex(ascending("i")).printResults("Created an index named: ")
Get a List of Indexes on a Collection
Use the listIndexes()
method to get a list of indexes.
collection.listIndexes().printResults()
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 use the Indexes.text
static helper:
The following example creates a text index by specifying the string literal “text” in the index document, then insert some sample documents. Using a for comprehension we can combine the two operations:
val indexAndInsert = for {
indexResults <- collection.createIndex(Document("content" -> "text"))
insertResults <- collection.insertMany(List(
Document("_id" -> 0, "content" -> "textual content"),
Document("_id" -> 1, "content" -> "additional content"),
Document("_id" -> 2, "content" -> "irrelevant content"))
)
} yield insertResults
indexAndInsert.results()
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):
// Find using the text index
collection.count(text("textual content -irrelevant")).printResults("Text search matches: ")
// Find using the $language operator
val textSearch: Bson = text("textual content -irrelevant", TextSearchOptions().language("english"))
collection.count(textSearch).printResults("Text search matches (english): ")
// Find the highest scoring match
collection.find(textSearch)
.projection(metaTextScore("score"))
.first()
.printHeadResult("Highest scoring document: ")
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
While not all commands have a specific helper, however you can run any command
by using the runCommand()
method. Here we call the buildInfo command:
database.runCommand(Document("buildInfo" -> 1)).printHeadResult()
important
If no readPreference
is passed
to runCommand
then the command will be run on the primary node.