Apache Cassandra的DataStax Node.js驱动程序

You can retrieve the user address details as a regular JavaScript object.

const query = 'SELECT name, address FROM users WHERE key = ?';const result = await client.execute(query, [ key ], { prepare: true });const row = result.first();const address = row.address;console.log('User lives in %s, %s - %s', address.street, address.city, address.state);

Read more information about using UDTs with the Node.js Driver.

Paging

All driver methods use a default fetchSize of 5000 rows, retrieving only first page of results up to a maximum of 5000 rows to shield an application against accidentally retrieving large result sets in a single response.

stream() method automatically fetches the following page once the current one was read. You can also use eachRow() method to retrieve the following pages by using autoPage flag. See [paging documentation for more information][doc-paging].

Batch multiple statements

You can execute multiple statements in a batch to update/insert several rows atomically even in different column families.

const queries = [ { query: 'UPDATE user_profiles SET email=? WHERE key=?', params: [ emailAddress, 'hendrix' ] }, { query: 'INSERT INTO user_track (key, text, date) VALUES (?, ?, ?)', params: [ 'hendrix', 'Changed email', new Date() ] }];await client.batch(queries, { prepare: true });console.log('Data updated on cluster');

Object Mapper

The driver provides a built-in object mapper that lets you interact with your data like you would interact with a set of documents.

Retrieving objects from the database:

const videos = await videoMapper.find({ userId });for (let video of videos) { console.log(video.name);}

Updating an object from the database:

await videoMapper.update({ id, userId, name, addedDate, description });

You can read more information about getting started with the Mapper in our documentation.

Data types

There are few data types defined in the ECMAScript specification, this usually represents a problem when you are trying to deal with data types that come from other systems in JavaScript.

The driver supports all the CQL data types in Apache Cassandra (3.0 and below) even for types with no built-in JavaScript representation, like decimal, varint and bigint. Check the documentation on working with numerical values, uuids and collections.

Logging

Instances of Client() are EventEmitter and emit log events:

client.on('log', (level, loggerName, message, furtherInfo) => { console.log(`${level} - ${loggerName}: ${message}`);});

The level being passed to the listener can be verbose, info, warning or error. Visit the logging documentation for more information.

Compatibility

Apache Cassandra versions 2.1 and above.DataStax Enterprise versions 4.8 and above.Node.js versions 8 and above.

Note: DataStax products do not support big-endian systems.

Credits

This driver is based on the original work of Jorge Bay on node-cassandra-cql and adds a series of advanced features that are common across all other DataStax drivers for Apache Cassandra.

The development effort to provide an up to date, high performance, fully featured Node.js Driver for Apache Cassandra will continue on this project, while node-cassandra-cql will be discontinued.

License

© DataStax, 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://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.

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