Hello World
Install, connect, try. A quick start guide to get you up and running with Couchbase and the Scala SDK.
Couchbase has a simple interface for creating and modifying records in a document, based upon the collection into which the documents are organized. You can read more about data modeling below, but first let’s look at those data operations, and installing the Scala SDK.
val docId = UUID.randomUUID().toString
collection.upsert(docId, json) match {
case Success(result) =>
case Failure(exception) => println("Error: " + exception)
}
upsert
inserts (creates) the document if it does not exist, or replaces it if it does.
We’ll explore creating and retrieving data records in more detail below
(and touch lightly upon a little of Scala’s functional programming approach as we go),
after walking through a quick installation.
Before You Start
Couchbase Capella, our Database-as-a-Service, lets you get on with what matters, while we take care of the administration for you. Alternately, if you need to control every aspect of deployment — or just want to run the Server in a VM on your laptop — there are several self-managed options available:
-
Couchbase Capella
-
Self-Managed Couchbase Server
If you haven’t already got a cluster set up, the easiest route is to sign up to Couchbase Capella and deploy a free tier cluster, then come back to this page. Make a note of the endpoint to connect to, and remember the credentials for the user that you set up.
Install Couchbase Server locally, or in your private Cloud:
For the example code below to run, you’ll need the username and password of the Administrator user that you create, and the IP address of at least one of the nodes of the cluster.
Prerequisites
-
The Scala SDK is tested against LTS versions of Oracle JDK and OpenJDK — see the compatibility docs.
-
The Couchbase Scala SDK 1.7 Client supports Scala 2.12 and 2.13.
The code examples also assume:
-
Couchbase Capella
-
Self-Managed Couchbase Server
-
You have signed up to Couchbase Capella.
-
You have created your own bucket, or loaded the Travel Sample dataset. Note, the Travel Sample dataset is installed automatically when deploying a Capella free tier cluster.
-
A user is created with permissions to access the cluster (at least Application Access permissions). See the Capella connection page for more details.
Couchbase Capella uses Roles to control user access to cluster resources. For the purposes of this guide, you can use the Organization Owner role automatically assigned to your account during installation of the Capella cluster. In production, Couchbase strongly recommends setting up users with more granular access roles as a best practice for data security. |
-
Couchbase Server is installed and accessible locally.
-
You have created your own bucket, or loaded the Travel Sample dataset using the Web interface.
-
A user is created with permissions to access your cluster (at least Application Access permissions). See Manage Users, Groups and Roles for more details.
Couchbase Server uses Role-Based Access Control (RBAC) to control access to cluster resources. In this guide we suggest using the Full Admin role created during setup of your local Couchbase Server cluster. In production, Couchbase strongly recommends setting up users with more granular access roles as a best practice for data security. |
Installation
More details of the installation process are in the full installation guide. In most cases, given the above prerequisites, it’s a simple matter of the following for your favorite build tool:
-
Scala Build Tool (SBT)
-
Gradle
-
Maven
libraryDependencies += "com.couchbase.client" %% "scala-client" % "1.7.3"
This will automatically use the Scala 2.12 or 2.13 builds, as appropriate for your SBT project.
For Scala 2.13, include the following in your build.gradle
:
dependencies {
compile group: 'com.couchbase.client', name: 'scala-client_2.13', version: '1.7.3'
}
For Scala 2.12, refer to the full Installation page.
For Scala 2.13, include the following in your Maven pom.xml
:
<dependencies>
<dependency>
<groupId>com.couchbase.client</groupId>
<artifactId>scala-client_2.13</artifactId>
<version>1.7.3</version>
</dependency>
</dependencies>
For Scala 2.12, refer to the full Installation page.
IDE Plugins
To make development easier, Couchbase plugins are available for VSCode and the IntelliJ family of IDEs and editors. For links and more information on these and other integrations across the Scala ecosystem, check out the Integrations & Ecosystem page.
Grab the Code
If you’re all set up and in a real hurry, just grab this code sample and add in your Capella details.
Complete Hello World code sample [Click to open or collapse the listing]
/* * Copyright (c) 2024 Couchbase, Inc. * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ // tag::imports[] import com.couchbase.client.scala.durability.Durability import com.couchbase.client.scala.env.{ ClusterEnvironment, SecurityConfig, TimeoutConfig } import com.couchbase.client.scala.json.{JsonObject, JsonObjectSafe} import com.couchbase.client.scala.kv.ReplaceOptions import com.couchbase.client.scala.{Cluster, ClusterOptions} import io.netty.handler.ssl.util.InsecureTrustManagerFactory import java.nio.file.Path import java.util.UUID import scala.concurrent.duration._ import scala.util.{Failure, Success, Try} // end::imports[] object Cloud { def main(args: Array[String]): Unit = { // tag::connect[] // Update this to your cluster val endpoint = "cb.<your-endpoint>.cloud.couchbase.com" val username = "username" val password = "Password!123" val bucketName = "travel-sample" val env = ClusterEnvironment.builder .securityConfig( SecurityConfig() .enableTls(true) ) // Sets a pre-configured profile called "wan-development" to help avoid latency issues // when accessing Capella from a different Wide Area Network // or Availability Zone (e.g. your laptop). .applyProfile(ClusterEnvironment.WanDevelopmentProfile) .build .get val cluster = Cluster .connect( "couchbases://" + endpoint, ClusterOptions .create(username, password) .environment(env) ) .get // end::connect[] // tag::bucket[] val bucket = cluster.bucket(bucketName) bucket.waitUntilReady(30.seconds).get // end::bucket[] // tag::collection[] val collection = bucket.scope("inventory").collection("airport") // end::collection[] // tag::json[] val json = JsonObject("status" -> "awesome") // end::json[] // tag::upsert[] val docId = UUID.randomUUID().toString collection.upsert(docId, json) match { case Success(result) => case Failure(exception) => println("Error: " + exception) } // end::upsert[] // tag::get[] // Get a document collection.get(docId) match { case Success(result) => // Convert the content to a JsonObjectSafe result.contentAs[JsonObjectSafe] match { case Success(json) => // Pull out the JSON's status field, if it exists json.str("status") match { case Success(hello) => println(s"Couchbase is $hello") case _ => println("Field 'status' did not exist") } case Failure(err) => println("Error decoding result: " + err) } case Failure(err) => println("Error getting document: " + err) } // end::get[] def getFor() { // tag::get-for[] val result: Try[String] = for { result <- collection.get(docId) json <- result.contentAs[JsonObjectSafe] status <- json.str("status") } yield status result match { case Success(status) => println(s"Couchbase is $status") case Failure(err) => println("Error: " + err) } // end::get-for[] } def getMap() { // tag::get-map[] val result: Try[String] = collection .get(docId) .flatMap(_.contentAs[JsonObjectSafe]) .flatMap(_.str("status")) result match { case Success(status) => println(s"Couchbase is $status") case Failure(err) => println("Error: " + err) } // end::get-map[] } def replaceOptions() { // tag::replace-options[] collection.replace( docId, json, ReplaceOptions() .expiry(10.seconds) .durability(Durability.Majority) ) match { case Success(status) => case Failure(err) => println("Error: " + err) } // end::replace-options[] } def replaceNamed() { // tag::replace-named[] collection.replace(docId, json, durability = Durability.Majority) match { case Success(status) => case Failure(err) => println("Error: " + err) } // end::replace-named[] } } }
Otherwise, read on as we introduce the CRUD API and connection to Capella or self-managed Couchbase Server.
There’s a View link to the complete sample code on GitHub above each of the snippets on these SDK pages, and a Copy icon to grab just the snippet shown. |
Connect to your Database
Connect to your Couchbase Capella operational cluster (or your local Couchbase Cluster, if you are trying out self-managed Couchbase).
-
Couchbase Capella
-
Self-Managed Couchbase Server
-
Cloud Native Gateway (CNG)
// Update this to your cluster
val endpoint = "cb.<your-endpoint>.cloud.couchbase.com"
val username = "username"
val password = "Password!123"
val bucketName = "travel-sample"
val env = ClusterEnvironment.builder
.securityConfig(
SecurityConfig()
.enableTls(true)
)
// Sets a pre-configured profile called "wan-development" to help avoid latency issues
// when accessing Capella from a different Wide Area Network
// or Availability Zone (e.g. your laptop).
.applyProfile(ClusterEnvironment.WanDevelopmentProfile)
.build
.get
val cluster = Cluster
.connect(
"couchbases://" + endpoint,
ClusterOptions
.create(username, password)
.environment(env)
)
.get
Note, the client certificate for connecting to a Capella cluster is included in the SDK installation.
// Update this to your cluster
val username = "Administrator"
val password = "password"
val bucketName = "travel-sample"
val env = ClusterEnvironment.builder
// You should uncomment this if running in a production environment.
// .securityConfig(
// SecurityConfig()
// .enableTls(true)
// )
.build
.get
val cluster = Cluster
.connect(
// For a secure cluster connection, use `couchbases://<your-cluster-ip>` instead.
"couchbase://localhost",
ClusterOptions
.create(username, password)
.environment(env)
)
.get
Couchbase’s large number of ports across the URLs of many services can be proxied by using a couchbase2://
endpoint as the connection string — currently only compatible with recent versions of Couchbase Autonomous Operator:
.connect(
"couchbase2://10.12.14.16",
ClusterOptions
.create(username, password)
.environment(env)
)
Read more on the Connections page.
The ClusterEnvironment.builder
is covered more fully on the Clint Settings page.
Cluster.connect returns a Try[Cluster] , as the Scala client uses functional error handling and does not throw exceptions.
You’ll see examples later of how to better handle a Try , but for simplicity here we’ll assume the operation succeeded and get the result as a Cluster using .get .
|
For a deeper look at connection options, read Managing Connections.
The connection code for getting started uses the Administrator password that you were given during set up. In any production app you should create a role restricted to the permissions needed for your app — more on this in the Security documentation. |
Opening a Bucket
Following successful authentication, open the bucket with:
val bucket = cluster.bucket(bucketName)
bucket.waitUntilReady(30.seconds).get
waitUntilReady
is an optional call,
but it is good practice to use it.
Opening resources such as buckets is asynchronous — that is, the cluster.bucket
call returns immediately and proceeds in the background.
waitUntilReady
ensures that the bucket resource is fully loaded before proceeding.
If not present, then the first key-value (KV) operation on the bucket will wait for it to be ready.
As with the earlier Cluster.connect
, we use .get
on the result here for simplicity.
Collections allow documents to be grouped by purpose or theme, according to a specified scope — see data modeling, below.
Here we will use the airport
collection within the inventory
scope from travel-sample
bucket as an example.
val collection = bucket.scope("inventory").collection("airport")
Create, Read, Update, Delete
Couchbase documents are organized into buckets, scopes, and collections. CRUD operations — Create, Read, Update, Delete — can be performed upon documents in a collection.
JSON
We’ll create a snippet of JSON to work with, using the client’s own JSON library, but you can read about the Scala SDK’s support for other JSON libraries on the JSON Libraries page.
val json = JsonObject("status" -> "awesome")
Insert (Create) and Upsert
insert
and upsert
will both create a new document.
The difference between the two is that if a document with that key already exists, the insert
operation will fail,
while the upsert
operation will succeed, replacing the content.
We need to provide a unique ID as the key, and we’ll use a UUID here:
val docId = UUID.randomUUID().toString
collection.upsert(docId, json) match {
case Success(result) =>
case Failure(exception) => println("Error: " + exception)
}
Get (Read)
The get
method reads a document from a collection.
As mentioned above, the Scala SDK will not throw exceptions.
Instead, methods that can error — such as the upsert
above — will return a Scala Try
result, which can either be a Success
containing the result, or a Failure
containing a Throwable exception.
The easiest way to handle a single operation is with pattern matching, as shown above.
Now let’s get the data back (this example will look a little messy due the nested handling of multiple Try
results, but we’ll see how to clean it up shortly):
// Get a document
collection.get(docId) match {
case Success(result) =>
// Convert the content to a JsonObjectSafe
result.contentAs[JsonObjectSafe] match {
case Success(json) =>
// Pull out the JSON's status field, if it exists
json.str("status") match {
case Success(hello) => println(s"Couchbase is $hello")
case _ => println("Field 'status' did not exist")
}
case Failure(err) => println("Error decoding result: " + err)
}
case Failure(err) => println("Error getting document: " + err)
}
Here we’re fetching the value for the key docId
,
converting that value to a JsonObjectSafe
(a simple wrapper around JsonObject
that returns Try
results — see
JsonObjectSafe for details),
and then accessing the value of the status key as a String.
Better Error Handling
All three of these operations could fail, so there’s quite a lot of error handling code here to do something quite simple.
One way to improve on this is by using flatMap
, like this:
val result: Try[String] = collection
.get(docId)
.flatMap(_.contentAs[JsonObjectSafe])
.flatMap(_.str("status"))
result match {
case Success(status) => println(s"Couchbase is $status")
case Failure(err) => println("Error: " + err)
}
Alternatively, you can use a for-comprehension, like so:
val result: Try[String] = for {
result <- collection.get(docId)
json <- result.contentAs[JsonObjectSafe]
status <- json.str("status")
} yield status
result match {
case Success(status) => println(s"Couchbase is $status")
case Failure(err) => println("Error: " + err)
}
Either of these methods will stop on the first failed operation. So the final returned Try
contains either
a) Success
and the result of the final operation, indicating that everything was successful, or
b) Failure
with the error returned by the first failing operation.
Replace (Update) and Overloads
You’ll notice that most operations in the Scala SDK have two overloads. One will take an Options builder, which provides all possible options that operation takes. For instance:
collection.replace(
docId,
json,
ReplaceOptions()
.expiry(10.seconds)
.durability(Durability.Majority)
) match {
case Success(status) =>
case Failure(err) => println("Error: " + err)
}
These options blocks are implemented as Scala case classes: they are immutable data objects that return a copy of themselves on each change.
The other overload is provided purely for convenience. It takes named arguments instead of an Options object, and provides only the most commonly used options:
collection.replace(docId, json, durability = Durability.Majority) match {
case Success(status) =>
case Failure(err) => println("Error: " + err)
}
When you replace a document, it’s usually good practice to use optimistic locking. Otherwise, changes might get lost if two people change the same document at the same time. |
Remove (Delete)
The remove method deletes a document from a collection:
collection.remove("document-key") match {
case Success(result) => println("Document removed successfully")
case Failure(err: DocumentNotFoundException) =>
println("The document does not exist")
case Failure(err) => println("Error: " + err)
}
Data Modeling
Documents are organized into collections — collections of documents that belong together. You get to decide what it means to "belong." Developers usually put documents of the same type in the same collection.
For example, imagine you have two types of documents: customers and invoices.
You could put the customer documents in a collection called customers
, and the invoice documents in a collection called invoices
.
Each document belongs to exactly one collection. A document’s ID is unique within the collection.
Different scopes can hold collections with different names. There is no relationship between collections in different scopes. Each collection belongs to just one scope and a collection’s name is unique within the scope.
More details can be found on the Data Model page.
What Next?
Next Steps
-
Discover SQL++ — our SQL-family querying language.
-
Explore some of the third party integrations with Couchbase and the Scala SDK, across the Scala ecosystem.