Neo4j Driver for JavaScript
This is the official Neo4j driver for JavaScript.
Starting with 5.0, the Neo4j Drivers will be moving to a monthly release cadence. A minor version will be released on the last Friday of each month so as to maintain versioning consistency with the core product (Neo4j DBMS) which has also moved to a monthly cadence.
As a policy, patch versions will not be released except on rare occasions. Bug fixes and updates will go into the latest minor version and users should upgrade to that. Driver upgrades within a major version will never contain breaking API changes.
See also: https://neo4j.com/developer/kb/neo4j-supported-versions/
Resources to get you started:
What's New in 5.x
Including the Driver
In Node.js application
Stable channel:
npm install neo4j-driver
Pre-release channel:
npm install neo4j-driver@next
Please note that @next
only points to pre-releases that are not suitable for production use.
To get the latest stable release omit @next
part altogether or use @latest
instead.
var neo4j = require('neo4j-driver')
Driver instance should be closed when Node.js application exits:
driver.close()
otherwise application shutdown might hang or it might exit with a non-zero exit code.
In web browser
We build a special browser version of the driver, which supports connecting to Neo4j over WebSockets.
It can be included in an HTML page using one of the following tags:
<script src="lib/browser/neo4j-web.min.js"></script>
<script src="https://unpkg.com/neo4j-driver"></script>
<script src="https://unpkg.com/neo4j-driver@X.Y.Z/lib/browser/neo4j-web.min.js"></script>
<script src="https://cdn.jsdelivr.net/npm/neo4j-driver"></script>
<script src="https://cdn.jsdelivr.net/npm/neo4j-driver@X.Y.Z/lib/browser/neo4j-web.min.js"></script>
This will make a global neo4j
object available, where you can create a driver instance with neo4j.driver
:
var driver = neo4j.driver(
'neo4j://localhost',
neo4j.auth.basic('neo4j', 'password')
)
From 5.4.0
, this version is also exported as ECMA Script Module.
It can be imported from a module using the following statements:
import neo4j from 'lib/browser/neo4j-web.esm.min.js'
import neo4j from 'https://unpkg.com/neo4j-driver@X.Y.Z/lib/browser/neo4j-web.esm.js'
import neo4j from 'https://unpkg.com/neo4j-driver@X.Y.Z/lib/browser/neo4j-web.esm.min.js'
import neo4j from 'https://cdn.jsdelivr.net/npm/neo4j-driver@X.Y.Z/lib/browser/neo4j-web.esm.js'
import neo4j from 'https://cdn.jsdelivr.net/npm/neo4j-driver@X.Y.Z/lib/browser/neo4j-web.esm.min.js'
It is not required to explicitly close the driver on a web page. Web browser should gracefully close all open
WebSockets when the page is unloaded. However, driver instance should be explicitly closed when it's lifetime
is not the same as the lifetime of the web page:
driver.close()
Usage examples
Constructing a Driver
var driver = neo4j.driver(
'neo4j://localhost',
neo4j.auth.basic('neo4j', 'password')
)
await driver.close()
Acquiring a Session
Regular Session
var session = driver.session()
with a Default Access Mode of READ
var session = driver.session({ defaultAccessMode: neo4j.session.READ })
with Bookmarks
var session = driver.session({
bookmarks: [bookmark1FromPreviousSession, bookmark2FromPreviousSession]
})
against a Database
var session = driver.session({
database: 'foo',
defaultAccessMode: neo4j.session.WRITE
})
Reactive Session
var rxSession = driver.rxSession()
with a Default Access Mode of READ
var rxSession = driver.rxSession({ defaultAccessMode: neo4j.session.READ })
with Bookmarks
var rxSession = driver.rxSession({
bookmarks: [bookmark1FromPreviousSession, bookmark2FromPreviousSession]
})
against a Database
var rxSession = driver.rxSession({
database: 'foo',
defaultAccessMode: neo4j.session.WRITE
})
Executing Queries
Consuming Records with Streaming API
session
.run('MERGE (alice:Person {name : $nameParam}) RETURN alice.name AS name', {
nameParam: 'Alice'
})
.subscribe({
onKeys: keys => {
console.log(keys)
},
onNext: record => {
console.log(record.get('name'))
},
onCompleted: () => {
session.close()
},
onError: error => {
console.log(error)
}
})
Subscriber API allows following combinations of onKeys
, onNext
, onCompleted
and onError
callback invocations:
- zero or one
onKeys
, - zero or more
onNext
followed by onCompleted
when operation was successful. onError
will not be invoked in this case - zero or more
onNext
followed by onError
when operation failed. Callback onError
might be invoked after couple onNext
invocations because records are streamed lazily by the database. onCompleted
will not be invoked in this case.
Consuming Records with Promise API
session
.run('MERGE (james:Person {name : $nameParam}) RETURN james.name AS name', {
nameParam: 'James'
})
.then(result => {
result.records.forEach(record => {
console.log(record.get('name'))
})
})
.catch(error => {
console.log(error)
})
.then(() => session.close())
Consuming Records with Reactive API
rxSession
.run('MERGE (james:Person {name: $nameParam}) RETURN james.name AS name', {
nameParam: 'Bob'
})
.records()
.pipe(
map(record => record.get('name')),
concatWith(rxSession.close())
)
.subscribe({
next: data => console.log(data),
complete: () => console.log('completed'),
error: err => console.log(err)
})
Transaction functions
neo4j.driver('neo4j://localhost', neo4j.auth.basic('neo4j', 'password'), {
maxTransactionRetryTime: 30000
})
Reading with Async Session
var readTxResultPromise = session.readTransaction(txc => {
var result = txc.run('MATCH (person:Person) RETURN person.name AS name')
return result
})
readTxResultPromise
.then(result => {
console.log(result.records)
})
.catch(error => {
console.log(error)
})
.then(() => session.close())
Reading with Reactive Session
rxSession
.readTransaction(txc =>
txc
.run('MATCH (person:Person) RETURN person.name AS name')
.records()
.pipe(map(record => record.get('name')))
)
.subscribe({
next: data => console.log(data),
complete: () => console.log('completed'),
error: err => console.log(error)
})
Writing with Async Session
var writeTxResultPromise = session.writeTransaction(async txc => {
var result = await txc.run(
"MERGE (alice:Person {name : 'Alice'}) RETURN alice.name AS name"
)
return result.records.map(record => record.get('name'))
})
writeTxResultPromise
.then(namesArray => {
console.log(namesArray)
})
.catch(error => {
console.log(error)
})
.then(() => session.close())
Writing with Reactive Session
rxSession
.writeTransaction(txc =>
txc
.run("MERGE (alice:Person {name: 'James'}) RETURN alice.name AS name")
.records()
.pipe(map(record => record.get('name')))
)
.subscribe({
next: data => console.log(data),
complete: () => console.log('completed'),
error: error => console.log(error)
})
Explicit Transactions
With Async Session
const txc = session.beginTransaction()
try {
const result1 = await txc.run(
'MERGE (bob:Person {name: $nameParam}) RETURN bob.name AS name',
{
nameParam: 'Bob'
}
)
result1.records.forEach(r => console.log(r.get('name')))
console.log('First query completed')
const result2 = await txc.run(
'MERGE (adam:Person {name: $nameParam}) RETURN adam.name AS name',
{
nameParam: 'Adam'
}
)
result2.records.forEach(r => console.log(r.get('name')))
console.log('Second query completed')
await txc.commit()
console.log('committed')
} catch (error) {
console.log(error)
await txc.rollback()
console.log('rolled back')
} finally {
await session.close()
}
With Reactive Session
rxSession
.beginTransaction()
.pipe(
mergeMap(txc =>
concatWith(
txc
.run(
'MERGE (bob:Person {name: $nameParam}) RETURN bob.name AS name',
{
nameParam: 'Bob'
}
)
.records()
.pipe(map(r => r.get('name'))),
of('First query completed'),
txc
.run(
'MERGE (adam:Person {name: $nameParam}) RETURN adam.name AS name',
{
nameParam: 'Adam'
}
)
.records()
.pipe(map(r => r.get('name'))),
of('Second query completed'),
txc.commit(),
of('committed')
).pipe(catchError(err => txc.rollback().pipe(throwError(() => err))))
)
)
.subscribe({
next: data => console.log(data),
complete: () => console.log('completed'),
error: error => console.log(error)
})
Numbers and the Integer type
The Neo4j type system uses 64-bit signed integer values. The range of values is between -(2
64
- 1)
and (2
63
- 1)
.
However, JavaScript can only safely represent integers between Number.MIN_SAFE_INTEGER
-(2
53
- 1)
and Number.MAX_SAFE_INTEGER
(2
53
- 1)
.
In order to support the full Neo4j type system, the driver will not automatically convert to javascript integers.
Any time the driver receives an integer value from Neo4j, it will be represented with an internal integer type by the driver.
Any javascript number value passed as a parameter will be recognized as Float
type.
Writing integers
Numbers written directly e.g. session.run("CREATE (n:Node {age: $age})", {age: 22})
will be of type Float
in Neo4j.
To write the age
as an integer the neo4j.int
method should be used:
var neo4j = require('neo4j-driver')
session.run('CREATE (n {age: $myIntParam})', { myIntParam: neo4j.int(22) })
To write an integer value that are not within the range of Number.MIN_SAFE_INTEGER
-(2
53
- 1)
and Number.MAX_SAFE_INTEGER
(2
53
- 1)
, use a string argument to neo4j.int
:
session.run('CREATE (n {age: $myIntParam})', {
myIntParam: neo4j.int('9223372036854775807')
})
Reading integers
In Neo4j, the type Integer can be larger what can be represented safely as an integer with JavaScript Number.
It is only safe to convert to a JavaScript Number if you know that the number will be in the range Number.MIN_SAFE_INTEGER
-(2
53
- 1)
and Number.MAX_SAFE_INTEGER
(2
53
- 1)
.
In order to facilitate working with integers the driver include neo4j.isInt
, neo4j.integer.inSafeRange
, neo4j.integer.toNumber
, and neo4j.integer.toString
.
var smallInteger = neo4j.int(123)
if (neo4j.integer.inSafeRange(smallInteger)) {
var aNumber = smallInteger.toNumber()
}
If you will be handling integers that is not within the JavaScript safe range of integers, you should convert the value to a string:
var largeInteger = neo4j.int('9223372036854775807')
if (!neo4j.integer.inSafeRange(largeInteger)) {
var integerAsString = largeInteger.toString()
}
Enabling native numbers
Starting from 1.6 version of the driver it is possible to configure it to only return native numbers instead of custom Integer
objects.
The configuration option affects all integers returned by the driver. Enabling this option can result in a loss of precision and incorrect numeric
values being returned if the database contains integer numbers outside of the range [Number.MIN_SAFE_INTEGER, Number.MAX_SAFE_INTEGER]
.
To enable potentially lossy integer values use the driver's configuration object:
var driver = neo4j.driver(
'neo4j://localhost',
neo4j.auth.basic('neo4j', 'password'),
{ disableLosslessIntegers: true }
)