Python quick start

At the end of this guide, you will have created a simple Python Hello, World! program that connects to the Memgraph database and executes simple queries.

Prerequisites

To follow this guide, you will need:

• A running Memgraph instance. If you need to setup Memgraph, take a look at the Installation guide.
• A basic understanding of graph databases and the property graph model.
• Docker installed and running. Instructions on how to setup Docker can be found on the official Docker website.
• The pymgclient driver. A Memgraph database adapter for the Python programming language. (if you are not using Docker)

info

NOTE: We recommend using Docker because it simplifies installing the driver dependencies. If you don't wish to use Docker, you will need to install the pymgclient driver locally.

Basic setup

We'll be using a Dockerized Python program to demonstrate how to connect to a running Memgraph database instance. If you don't wish to use Docker, the steps might be slightly different, but the code is most likely the same or very similar.

Let's jump in and connect a simple program to Memgraph.

1. Create a new directory for your program, for example /memgraph_python and position yourself in it.

2. Create a requirements.txt file which will contain a list of items to be installed using pip. Leave it empty for the purposes of this guide.

3. Create a new file in the project root directory /memgraph_python and name it Dockerfile. Add the following code to it:

# Set base image (host OS)
FROM python:3.8

# Install CMake
RUN apt-get update && \
  apt-get --yes install cmake

# Install mgclient
RUN apt-get install -y git cmake make gcc g++ libssl-dev && \
  git clone https://github.com/memgraph/mgclient.git /mgclient && \
  cd mgclient && \
  git checkout dd5dcaaed5d7c8b275fbfd5d2ecbfc5006fa5826 && \
  mkdir build && \
  cd build && \
  cmake .. && \
  make && \
  make install

# Install pymgclient
RUN git clone https://github.com/memgraph/pymgclient /pymgclient && \
  cd pymgclient && \
  python3 setup.py build && \
  python3 setup.py install

# Set the working directory in the container
WORKDIR /code

# Copy the dependencies file to the working directory
COPY requirements.txt .

# Install dependencies
RUN pip install -r requirements.txt

# Copy the content of the local src directory to the working directory
COPY src/ .

# Command to run on container start
CMD [ "python", "./program.py" ]

4. Create a directory for your source code, for example, /src and position yourself in it.

5. To make the actual program, create a new Python script. Name it program.py and add the following code:

import mgclient

# Make a connection to the database
connection = mgclient.connect(host='172.17.0.2', port=7687)

# Create a cursor for query execution
cursor = connection.cursor()

# Delete all nodes and relationships
query = "MATCH (n) DETACH DELETE n"

# Execute the query
cursor.execute(query)

# Create a node with the label FirstNode and message property with the value "Hello, World!"
query = """CREATE (n:FirstNode)
           SET n.message = '{message}'
           RETURN 'Node '  + id(n) + ': ' + n.message""".format(message="Hello, World!")

# Execute the query
cursor.execute(query)

# Fetch one row of query results
row = cursor.fetchone()

# Print the first member in row
print(row[0])

6. Don't forget to change the host address in your code. Find the CONTAINER ID with docker ps and use it in the following command to retrieve the address:

docker inspect -f '{{range.NetworkSettings.Networks}}{{.IPAddress}}{{end}}' CONTAINER ID

7. To run the application, first, you need to create a Docker image with:

docker build -t memgraph_python .

8. Now, you can run the application with the following command:

docker run memgraph_python

You should see an output similar to the following:

Node 1: Hello, World!

Where to next?

For real-world examples of how to use Memgraph, we suggest you take a look at the Tutorials page. You can also browse through the Database functionalities section to get an overview of all the functionalities Memgraph offers.

Getting help

Visit the Getting help page in case you run into any kind of problem or you have additional questions.