rethinkdbdash

rethinkdbdash

A Node.js driver for RethinkDB with promises and a connection pool.

Status: Beta

Quick start

---

Example wih koa:

var app = require('koa')();
var r = require('rethinkdbdash')();

app.use(function *(){
    var result = yield r.table("foo").get("bar").run();

    this.body = JSON.stringify(result);
});

app.listen(3000);

Example with bluebird:

var Promise = require('blubird');
var r = require('rethinkdbdash')();

var run = Promise.coroutine(function* () {
    var result

    try{
        result = yield r.table("foo").get("bar").run();
        console.log(JSON.stringify(result, null, 2));
    }
    catch(e) {
        console.log(e);
    }
})

Note: You have to start node with the --harmony flag.

Install

---

• Build node 0.11.10 (checkout v0.11.10-release) from source.
  Binaries won't work with node-protobuf -- some libraries are not properly linked.
• Install the libprotobuf binary and development files (required to build node-protobuf in the next step).
• Install rethinkdbdash with npm.

npm install rethinkdbdash

Documentation

---

While rethinkdbdash has almost the same syntax as the official driver, there are still a few differences.

This section will reference all the differences. For all the other methods not mentionned, please read the official driver's documentation.

The differences are:

Module name

Import rethinkdbdash:

var r = require('rethinkdbdash')(options);

options can be:

• {pool: false}
• the options for the connection pool, which can be:

{
    min: <number>, // minimum number of connections in the pool, default 50
    max: <number>, // maximum number of connections in the pool, default 1000
    bufferSize: <number>, // minimum number of connections available in the pool, default 50
    timeoutError: <number>, // wait time before reconnecting in case of an error (in ms), default 1000
    timeoutGb: <number>, // how long the pool keep a connection that hasn't been used (in ms), default 60*60*1000
}

Promises

Rethinkdbdash will return a bluebird promise when a method with the official driver takes a callback.

Example with yield - 1:

try{
    var cursor = yield r.table("foo").run();
    var result = yield cursor.toArray();
    //process(result);
}
else {
    console.log(e.message);
}

Example with yield - 2:

try{
    var cursor = yield r.table("foo").run();
    var row;
    while(cursor.hasNext()) {
        row = yield cursor.next();
        //process(row);
    }
}
else {
    console.log(e.message);
}

Example then and error:

r.table("foo).run().then(function(connection) {
    //...
}).error(function(e) {
    console.log(e.mssage)
})

Connection pool

Rethinkdbdash implements a connection pool and is created by default.

If you do not want to use a connection pool, iniitialize rethinkdbdash with {pool: false} like that:

var r = require('rethinkdbdash)({pool: false});

You can provide options for the connection pool with the following syntax:

var r = require('rethinkdbdash')({
    min: <number>, // minimum number of connections in the pool, default 50
    max: <number>, // maximum number of connections in the pool, default 1000
    bufferSize: <number>, // minimum number of connections available in the pool, default 50
    timeoutError: <number>, // wait time before reconnecting in case of an error (in ms), default 1000
    timeoutGb: <number>, // how long the pool keep a connection that hasn't been used (in ms), default 60*60*1000
});

try {
    var cursor = yield r.table("foo").run();
    var result = yield cursor.toArray(); // The connection used in the cursor will be released when all the data will be retrieved
}
catch(e) {
    console.log(e.message);
}

Get the number of connections

r.getPool().getLength();

Get the number of available connections

r.getPool().getAvailableLength();

Drain the pool

r.getPool().drain();

Note: If a query returns a cursor, the connection will not be released as long as the cursor hasn't fetch everything or has been closed.

Cursor

Rethinkdbdash will return a cursor as long as your result is a sequence.

var cursor = yield r.expr([1, 2, 3]).run()
console.log(JSON.stringify(cursor)) // will *not* print [1, 2, 3]

var result = yield cursor.toArray();
console.log(JSON.stringify(result)) // Will print [1, 2, 3]

Errors

• Better backtraces

Long backtraces are split on multiple lines.
In case the driver cannot parse the query, it will provide a better location of the error.

• Different handling for queries that cannot be parsed on the server.

In case an error occured because the server cannot parse the protobuf message, the official driver emits an error on the connection.
Rethinkdbdash emits an error and rejects all queries running on this connection and close the connection. This is the only way now to avoid having some part of your program hang forever.

Miscellaneous

• Maximum nesting depth

The maximum nesting depth is your documents is by default 100 (instead of 20). You can change this setting with

r.setNestingLevel(<number>)

• Performance

The tree representation of the query is built step by step and stored which avoid recomputing it if the query is re-run.
exprJSON, internal method used by insert, is more efficient in the worst case (O(n)).

• Connection

If you do not wish to use rethinkdbdash connection pool, you can implement yours. The connections created with rethinkdbdash will emit a "release" event when they receive an error, an atom, or the end (or full) sequence.

A connection can also emit a "timeout" event if the underlying connection times out.

Run tests

---

Update test/config.js if your RethinkDB instance doesn't run on the default parameters.

Run

mocha --harmony-generators

Tests are also being run on wercker:

• Builds: https://app.wercker.com/#applications/52dffe8ba4acb3ef16010ef8/tab
• Box:
  • Github: https://github.com/neumino/box-rethinkdbdash
  • Wercker builds: https://app.wercker.com/#applications/52dffc65a4acb3ef16010b60/tab

Roadmap

============

• Clean tests (refactor It)
• Add better tests for backtraces