MongoDB Sync Driver

Table of Contents

# Introduction

This sections covers the Mongock implementation for MongoDB java Driver 3.x and 4.x


# MongoDB driver options and compatibility

Mongock driver Driver library Version compatibility
mongodb-sync-v4-driver org.mongodb:mongodb-driver-sync 4.X.X
mongodb-v3-driver org.mongodb:mongo-java-driver 3.X.X

# MongoDB common configuration

All the MongoDB drivers share the same configuration.

When setting configuration via properties file, it must be prefixed by mongock.mongo-db

# Properties

Property Description Type Default value
writeConcern Exactly the same MongoDB parameter write concern. For more information, visit the official MongoDB documentation for write concern. Object {w:majority,
wTimeoutMs: null,
j:true}
readConcern Exactly the same MongoDB parameter read concern. For more information, visit the official MongoDB documentation for read concern. String majority
readPreference Exactly the same MongoDB parameter read preference. For more information, visit the official MongoDB documentation for read preference. String primary

# Get started

Following the get started section, this covers steps 3 and 5 and 6.

# - Add maven dependency for the driver (step 2)

<dependency>
  <groupId>io.mongock</groupId>
  <artifactId>mongodb-sync-v4-driver</artifactId>
  <!--<artifactId>mongodb-v3-driver</artifactId> for MongoDB driver v3-->
</dependency>

# - Build the driver (step 5)

These classes provide the same two static initializers

// For mongodb-sync-v4-driver
MongoSync4Driver driver = MongoSync4Driver.withDefaultLock(mongoClient, databaseName);
// For mongodb-v3-driver
//MongoCore3Driver driver = MongoCore3Driver.withDefaultLock(mongoClient, databaseName);
driver.setWriteConcern(WriteConcern.MAJORITY.withJournal(true).withWTimeout(1000, TimeUnit.MILLISECONDS));
driver.setReadConcern(ReadConcern.MAJORITY);
driver.setReadPreference(ReadPreference.primary());

# - Driver extra configuration (step 6)

# Transactions

Due to the MongoDB API design, to work with transactions the ClientSession object is required in every MongoDB driver operation.

Mongock makes this very simple. The developer only needs to specify a ClientSession parameter in the contructor or method of the @ChangeUnit and use it in the MongoDB operations. Mongock takes care of everything else.

The following code shows how to save documents inside the transaction using the ClientSession object.

  @Execution
  public void execution(ClientSession clientSession, MongoDatabase mongoDatabase) {
  
    mongoDatabase.getCollection(CLIENTS_COLLECTION_NAME, Client.class)
            .insertMany(clientSession, IntStream.range(0, INITIAL_CLIENTS)
                    .mapToObj(ClientInitializerChangeLog::getClient)
                    .collect(Collectors.toList()));
  }

# Examples

Please visit our example github repository for more information