Databases — Data Model
Initializer
Your first step in using the API must be to call its initializer. An exception is raised if any other API method is invoked before the initializer.
The init() API accepts no parameters.
// Initialize the Couchbase Lite system
CouchbaseLite.init();New Database
As the top-level entity in the API, new databases can be created using the Database class by passing in a name, configuration, or both.
The following example creates a database using the Database(String name, DatabaseConfiguration config) method.
DatabaseConfiguration config = new DatabaseConfiguration();
Database database = new Database(DB_NAME, config);Just as before, the database will be created in a default location.
Alternatively, the Database(string name, DatabaseConfiguration config) initializer can be used to provide specific options in the DatabaseConfiguration object such as the database directory.
Database Encryption
| This is an Enterprise Edition feature. |
Couchbase Lite on Java includes the ability to encrypt Couchbase Lite databases. This allows mobile applications to secure the data at rest, when it is being stored on the device. The algorithm used to encrypt the database is 256-bit AES.
To enable encryption, you must set the DatabaseConfiguration.encryptionKey property to the encryption key of your choice.
Provide this encryption key every time the database is opened.
DatabaseConfiguration config = new DatabaseConfiguration();
config.setEncryptionKey(new EncryptionKey("PASSWORD"));
Database database = new Database(DB_NAME, config);Couchbase Lite does not persist the key. It is the application’s responsibility to manage the key and store it in a platform specific secure store such as Apple’s Keychain or Android’s Keystore.
An encrypted database can only be opened with the same language SDK that was used to encrypt it in the first place (Swift, C#, Java, Java (Android) or Objective-C). For example, if a database is encrypted with the Swift SDK and then exported, it will only be readable with the Swift SDK.
Upgrading from 1.x when Encryption is Enabled
If you’re migrating an application from Couchbase Lite 1.x to 2.x, note that the automatic database upgrade functionality is not supported for encrypted databases. Thus, to upgrade an encrypted 1.x database, you should do the following:
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Disable encryption using the Couchbase Lite 1.x framework (see 1.x encryption guide)
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Open the database file with encryption enabled using the Couchbase Lite 2.x framework.
Since it is not possible to package Couchbase Lite 1.x and Couchbase Lite 2.x in the same application this upgrade path would require two successive upgrades. If you are using Sync Gateway to synchronize the database content, it may be preferable to run a pull replication from a new 2.x database with encryption enabled and delete the 1.x local database.
Finding a Database File
By default a Couchbase Lite on Java database is created in a directory at the current location called <databaseName>.cblite2.
This location is set by the DatabaseConfiguration method. You should always use it to explicitly set the database location. See the following example for how to do this:
DatabaseConfiguration thisConfig = new DatabaseConfiguration(); thisConfig.setDirectory("yourDBpath");
Database thisDB = new Database("db", thisConfig);Command Line Tool
cblite is a command-line tool for inspecting and querying Couchbase Lite 2.x databases.
You can download and build it from the couchbaselabs GitHub repository.
Note that the cblite tool is not supported by the Couchbase Support Policy.
Logging
If you are using a Couchbase Lite release prior to 2.5 see Deprecated functionality
From version 2.5, Couchbase Lite provides a logging API that unifies the logging behavior across all platforms, making debugging and troubleshooting easier during development and in production.
| The retrieval of logs from the device is out of scope of this feature. |
Available logging features include:
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Console based logging
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File based logging
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Custom logging
Console based logging
Default: Enabled.
Console based logging is often used to facilitate troubleshooting during development.
File based logging
Default: Disabled.
Available file based logging formats:
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Binary — most efficient for storage and performance. It is the default for file based logging.
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Plaintext
We recommend using the binary log format and a decoder, such as cbl-log, to view them. Download cbl-log from couchbaselabs/couchbase-mobile-tools.
| See Decoding binary logs. |
The following example enables file based logging.
final File path = new File("/usr/local/MyApp/logs")
Database.log.getFile().setConfig(new LogFileConfiguration(path.toString()));
Database.log.getFile().setLevel(LogLevel.INFO);Custom logging
Default: Disabled.
Allows registration of a callback function to receive Couchbase Lite log messages, which may be logged using any external logging framework.
Apps must implement the Logger interface, as shown below:
class LogTestLogger implements Logger {
@NonNull
private final LogLevel level;
public LogTestLogger(@NonNull LogLevel level) { this.level = level; }
@NonNull
@Override
public LogLevel getLevel() { return level; }
@Override
public void log(@NonNull LogLevel level, @NonNull LogDomain domain, @NonNull String message) {
// this method will never be called if param level < this.level
// handle the message, for example piping it to a third party framework
}
}And set it on the custom property.
// this custom logger will never be asked to log an event
// with a log level < WARNING
Database.log.setCustom(new LogTestLogger(LogLevel.WARNING));Decoding binary logs
The cbl-log tool should be used to decode binary log files as shown in these examples.
Download the cbl-log tool using wget.
wget https://packages.couchbase.com/releases/couchbase-lite-log/2.8.0/couchbase-lite-log-2.8.0-macos.zipNavigate to the bin directory and run the cbl-log executable.
$ ./cbl-log logcat LOGFILE <OUTPUT_PATH>Download the cbl-log tool using wget.
wget https://packages.couchbase.com/releases/couchbase-lite-log/2.8.0/couchbase-lite-log-2.8.0-centos.zipNavigate to the bin directory and run the cbl-log executable.
cbl-log logcat LOGFILE <OUTPUT_PATH>Download the cbl-log tool using PowerShell.
Invoke-WebRequest https://packages.couchbase.com/releases/couchbase-lite-log/2.8.0/couchbase-lite-log-2.8.0-windows.zip -OutFile couchbase-lite-log-2.8.0-windows.zipRun the cbl-log executable.
$ .\cbl-log.exe logcat LOGFILE <OUTPUT_PATH>Logging Functionality Prior To Release 2.5
|
Deprecation
The pre-Couchbase Lite 2.5 logging functionality is deprecated.
It was superseded by an enhanced Logging API in that release.
This information is included for completeness only.
|
The log messages are split into different domains (LogDomains) which can be tuned to different log levels.
The following example enables verbose logging for the replicator and query domains.
Database.setLogLevel(LogDomain.REPLICATOR, LogLevel.VERBOSE);
Database.setLogLevel(LogDomain.QUERY, LogLevel.VERBOSE);Loading a Pre-Built Database
If your app needs to sync a lot of data initially, but that data is fairly static and won’t change much, it can be a lot more efficient to bundle a database in your application and install it on the first launch. Even if some of the content changes on the server after you create the app, the app’s first pull replication will bring the database up to date.
To use a prebuilt database, you need to set up the database, build the database into your app bundle as a resource, and install the database during the initial launch. After your app launches, it needs to check whether the database exists.
If the database does not exist, the app should copy it using the following method.
// Note: Getting the path to a database is platform-specific.
// For Android you need to extract it from your
// assets to a temporary directory and then pass that path to Database.copy()
DatabaseConfiguration configuration = new DatabaseConfiguration();
if (!Database.exists("travel-sample", APP_DB_DIR)) {
File tmpDir = new File(System.getProperty("java.io.tmpdir"));
ZipUtils.unzip(getAsset("travel-sample.cblite2.zip"), tmpDir);
File path = new File(tmpDir, "travel-sample");
try {
Database.copy(path, "travel-sample", configuration);
} catch (CouchbaseLiteException e) {
e.printStackTrace();
}
}In the example below, the ZipUtils.unzip method copies the zipped pre-built database from the application’s resource directory to the files directory.
This method is provided below for information as it isn’t included in the Couchbase Lite library.
public class ZipUtils {
public static void unzip(InputStream in, File destination) throws IOException {
byte[] buffer = new byte[1024];
ZipInputStream zis = new ZipInputStream(in);
ZipEntry ze = zis.getNextEntry();
while (ze != null) {
String fileName = ze.getName();
File newFile = new File(destination, fileName);
if (ze.isDirectory()) {
newFile.mkdirs();
} else {
new File(newFile.getParent()).mkdirs();
FileOutputStream fos = new FileOutputStream(newFile);
int len;
while ((len = zis.read(buffer)) > 0) {
fos.write(buffer, 0, len);
}
fos.close();
}
ze = zis.getNextEntry();
}
zis.closeEntry();
zis.close();
in.close();
}
}