Elassandra Support (elassandra 5.5 or above)

Configure Auto Index Management

If you are a user of elassandra, then express-cassandra provides built in index management functionality for you. If enabled, express-cassandra will automatically create and manage an index with the same name as your keyspace and create type mapping for your tables according to an es_index_mapping defined in your table model schema. To enable auto index management, make sure to use the NetworkTopologyStrategy as the replication strategy and set manageESIndex: true in the ormOptions like the following:

{
    clientOptions: {
        // omitted other options for clarity
    },
    ormOptions: {
        // omitted other options for clarity
        defaultReplicationStrategy: {
            class: 'NetworkTopologyStrategy',
            DC1: 1
        },
    migration: 'alter',
        manageESIndex: true
    }
}

Elassandra does not work with the SimpleStrategy replication class. You can still have a single Elassandra node. The DC1 parameter is the case sensitive name of the Data Center as defined in your elassandra/conf/cassandra-rackdc.properties file. You may also have to edit your elassandra/conf/cassandra-topology.properties file to match the rack data center declarations. If you did not edit those files, the default is DC1. These parameters are used with the CREATE KEYSPACE CQL command.

Note that you can optionally provide connection options for elasticsearch in the clientOptions like the following. If omitted, then the cassandra contactPoints are used as default host addresses with sniffOnStart: true as default configuration for the elasticsearch client.

{
    clientOptions: {
        // omitted other options for clarity
        elasticsearch: {
            host: 'http://localhost:9200',
            apiVersion: '5.5',
            sniffOnStart: true
        }
    },
    ormOptions: {
        // omitted other options for clarity
        defaultReplicationStrategy: {
            class: 'NetworkTopologyStrategy',
            DC1: 1
        },
        migration: 'alter',
        manageESIndex: true
    }
}

Note that any config option elasticsearch js client supports can be used in the above elasticsearch configuration block.

Define Elasticsearch Mapping for a Table Schema:

To keep all your cassandra table fields synced into the elasticsearch index, use the discover option from elassandra like the following schema for an example User model:

// User model
module.exports = {
  fields: {
    id: 'varchar',
    name: 'text',
    score: 'int'
  },
  key: ['id'],
  es_index_mapping: {
    discover: '.*',
  }
};

By default, all text columns are mapped with "index":"not_analyzed". To overwrite some properties, you could do the following:

// User model
module.exports = {
  fields: {
    id: 'varchar',
    name: 'text',
    score: 'int'
  },
  key: ['id'],
  es_index_mapping: {
    discover: '.*',
    properties: {
        "name" : {
            "type" : "string",
            "index" : "analyzed"
        }
    }
  }
};

Elassandra mapping docs contain details about possible mapping parameters and customizations that can be defined here.

Search Elasticsearch Index Mapping for the Table:

You can now use the search method to do an elasticsearch query like the following:

models.instance.User.search({
    q: 'name:John'
}, function(err, response) {
    if (err) throw err;

    console.log(response);
});

You could also use the optional from and size parameters to paginate, sort parameter to sort and provide the body parameter to use elasticsearch query dsl:

var pageNum = 2;
var perPage = 30;

models.instance.User.search({
    from: (pageNum - 1) * perPage,
    size: perPage,
    sort: ['score:desc'],
    body: {
        query: {
            match: {
                name: 'john'
            }
        }
    }
}, function(err, response) {
    if (err) throw err;

    console.log(response);
});

You could also use the get_es_client() method to get the elasticsearch client instance and do any operations that the elasticsearch js client supports. For example you could count the total number of users like the following:

const esClient = models.instance.User.get_es_client();
const modelKeyspaceName = models.instance.MultipleOrderBy.get_keyspace_name();
const modelTableName = models.instance.User.get_table_name();
const modelIndexName = modelKeyspaceName + '_' + modelTableName;

esClient.count({
    index: modelIndexName,
    type: modelTableName
}, function(err, response) {
    if (err) throw err;

    console.log(response.count);
});