The Py2neo Handbook¶
Py2neo is a client library and toolkit for working with Neo4j from within Python applications and from the command line. The library supports both Bolt and HTTP and provides a high level API, an OGM, admin tools, an interactive console, a Cypher lexer for Pygments, and many other bells and whistles.
As of version 2021.1, Py2neo contains full support for routing, as exposed by a Neo4j cluster.
This can be enabled using a neo4j://... URI or by passing routing=True to a Graph constructor.
Remember to take a look at the full release notes for version 2021.1.
Quick Example¶
To run a query against a local database is straightforward:
>>> from py2neo import Graph
>>> graph = Graph("bolt://localhost:7687", auth=("neo4j", "password"))
>>> graph.run("UNWIND range(1, 3) AS n RETURN n, n * n as n_sq")
n | n_sq
-----|------
1 | 1
2 | 4
3 | 9
Releases & Versioning¶
As of 2020, py2neo has switched to Calendar Versioning, using a scheme of YYYY.N.M.
Here, N is an incrementing zero-based number for each year, and M is a revision within that version (also zero-based).
No compatibility guarantees are given between versions, but as a general rule, a change in M should require little-to-no work within client applications,
whereas a change in N may require some work. A change to the year is likely to require a more significant amount of work to upgrade.
Note that py2neo is developed on a rolling basis, so patches are not made to old versions. Users will instead need to install the latest release to adopt bug fixes.
Installation¶
To install the latest release of py2neo, simply use:
$ pip install --upgrade py2neo
To install the latest stable code from the GitHub master branch, use:
$ pip install git+https://github.com/technige/py2neo.git@master#egg=py2neo
Requirements¶
The following versions of Python and Neo4j (all editions) are supported:
Python 2.7 / 3.4 / 3.5 / 3.6 / 3.7 / 3.8 / 3.9
Neo4j 3.4 / 3.5 / 4.0 / 4.1 / 4.2 / 4.3 (the latest point release of each version is recommended)
Py2neo provides support for the multi-database functionality added in Neo4j 4.0.
More about this can be found in the documentation for the Graph class.
Note that Py2neo is developed and tested under Linux using standard CPython distributions. While other operating systems and Python distributions may work, support for these is not available.
Core Graph API¶
Py2neo consists of several distinct regions of API, the heart of which is the Graph API. This has evolved from the original, foundational API included with early versions of the library, and remains relevant for general purpose use today.
The Graph class represents a graph database exposed by a
Neo4j service running on a single instance or cluster, and which
provides access to a large portion of the most commonly used py2neo
features. The full DBMS is represented by a GraphService
object.
For convenience, all core functions and classes are exported from the
py2neo root namespace. This includes all connectivity and database
management functionality as well as entity matching and core errors.
Data Types¶
The Node and Relationship objects are key to this library, both of which extend the Subgraph class.
A comprehensive set of graph structure data types and operations are provided, allowing great flexibility in how graph data can be used.
