Getting Started

The Mapper is provided as part of the driver package.

const cassandra = require('cassandra-driver');
const Client = cassandra.Client;
const Mapper = cassandra.mapping.Mapper;

const client = new Client({ contactPoints, localDataCenter, keyspace });

Create a Mapper instance and reuse it across your application. You can define how your model properties are mapped to table columns in the MappingOptions.

const mapper = new Mapper(client, { 
  models: { 'Video': { tables: ['videos'] } }
});

A ModelMapper contains all the logic to retrieve and save objects from and to the database.

const videoMapper = mapper.forModel('Video');

Internally, the Mapper contains a single ModelMapper instance per model in your application, you can call mapper.forModel(name) each time you need a model mapper with no additional cost.

To retrieve a single object, use get() method of the ModelMapper.

const video = await videoMapper.get({ videoId: myVideoId });

Use find() method to filter by one or more primary keys.

const userVideos = await videoMapper.find({ userId: myUserId });

Insert an object using insert() method.

await videoMapper.insert({ videoId, userId, addedDate, name });

Update an object using update() method.

await videoMapper.update({ videoId, userId, addedDate, name: newName });

Delete an object using remove() method.

await videoMapper.remove({ videoId });

Keep in mind that both Mapper and Client instances are designed to be long lived. If you don’t want to maintain both instances on separate fields, you can access the Client instance using the Mapper property client. For example, you can shutdown your Client before exiting your application by calling:

mapper.client.shutdown();

You can look at the Queries documentation for more examples of retrieving and saving objects and you read the Mappings documentation to understand how tables and columns are mapped into properties.

Note that throughout the Mapper documentation the killrvideo schema is used.

Getting Started

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