Quickstart in Couchbase with Flask and Python

REST API using Couchbase Capella in Python using Flask

Often, the first step developers do after creating their database is to create a REST API that can perform Create, Read, Update, and Delete (CRUD) operations for that database. This repo is designed to teach you and give you a starter project (in Python using Flask) to generate such a REST API. After you have installed travel-sample bucket in your database, you can run this application which is a REST API with Swagger documentation so that you can learn:

1. How to create, read, update, and delete documents using Key Value operations (KV operations). KV operations are unique to couchbase and provide super fast (think microseconds) queries.
2. How to write simple parametrized SQL++ queries using the built-in travel-sample bucket.

Full documentation for the tutorial can be found on the Couchbase Developer Portal.

If you are looking for a quickstart using FastAPI, you can find it in this repo.

Prerequisites

To run this prebuilt project, you will need:

• Couchbase Capella cluster with travel-sample bucket loaded.
  • To run this tutorial using a self managed Couchbase cluster, please refer to the appendix.
• Python 3.9 or higher installed
  • Ensure that the Python version is compatible with the Couchbase SDK.
• Loading Travel Sample Bucket If travel-sample is not loaded in your Capella cluster, you can load it by following the instructions for your Capella Cluster:
  • Load travel-sample bucket in Couchbase Capella

App Setup

We will walk through the different steps required to get the application running.

Cloning Repo

git clone https://github.com/couchbase-examples/python-quickstart.git

Install Dependencies

The dependencies for the application are specified in the requirements.txt file in the source folder. Dependencies can be installed through pip the default package manager for Python.

Note: If your Python is not symbolically linked to python3, you need to run all commands using python3 instead of python.

cd src
python -m pip install -r requirements.txt

Note: Python SDKs older than version 4.1.9 require OpenSSL v1.1. This might not be the default in some newer platforms. In such scenarios, please install the SDK without using the prebuilt wheels

python -m pip install couchbase --no-binary couchbase

Refer to the instructions in the SDK for more info.

Setup Database Configuration

To know more about connecting to your Capella cluster, please follow the instructions.

Specifically, you need to do the following:

• Create the database credentials to access the travel-sample bucket (Read and Write) used in the application.
• Allow access to the Cluster from the IP on which the application is running.

All configuration for communication with the database is read from the environment variables. We have provided a convenience feature in this quickstart to read the environment variables from a local file, .env in the source folder.

Create a copy of .env.example file and rename it to .env and add the values for the Couchbase connection.

DB_CONN_STR=<connection_string>
DB_USERNAME=<user_with_read_write_permission_to_travel-sample_bucket>
DB_PASSWORD=<password_for_user>

Note: The connection string expects the couchbases:// or couchbase:// part.

Running The Application

Directly on Machine

At this point, we have installed the dependencies, loaded the travel-sample data and configured the application with the credentials. The application is now ready and you can run it.

cd src
python app.py

Using Docker

• Build the Docker image

cd src
docker build -t couchbase-flask-quickstart .

• Run the Docker image

docker run -it --env-file .env -p 8080:8080 couchbase-flask-quickstart

Note: The .env file has the connection information to connect to your Capella cluster. These will be part of the environment variables in the Docker container.

Verifying the Application

Once the application starts, you can see the details of the application on the logs.

The application will run on port 8080 of your local machine (http://localhost:8080). You will find the interactive Swagger documentation of the API if you go to the URL in your browser. Swagger documentation is used in this demo to showcase the different API end points and how they can be invoked. More details on the Swagger documentation can be found in the appendix.

Running Tests

To run the integration tests, use the following commands:

cd src
python -m pytest

Appendix

Data Model

For this quickstart, we use three collections, airport, airline and routes that contain sample airports, airlines and airline routes respectively. The routes collection connects the airports and airlines as seen in the figure below. We use these connections in the quickstart to generate airports that are directly connected and airlines connecting to a destination airport. Note that these are just examples to highlight how you can use SQL++ queries to join the collections.

Extending API by Adding New Entity

If you would like to add another entity to the APIs, these are the steps to follow:

• Create the new entity (collection) in the Couchbase bucket. You can create the collection using the SDK or via the Couchbase Server interface.
• Define the routes in a new file in the api folder similar to the existing routes like airport.py.
• Add the new routes to the application in app.py.
• Add the tests for the new routes in a new file in the tests folder similar to test_airport.py.

Running Self Managed Couchbase Cluster

If you are running this quickstart with a self managed Couchbase cluster, you need to load the travel-sample data bucket in your cluster and generate the credentials for the bucket.

You need to update the connection string and the credentials in the .env file in the source folder.

Note: Couchbase Server version 7 or higher must be installed and running prior to running the Flask Python app.

Swagger Documentation

Swagger documentation provides a clear view of the API including endpoints, HTTP methods, request parameters, and response objects.

Click on an individual endpoint to expand it and see detailed information. This includes the endpoint's description, possible response status codes, and the request parameters it accepts.

Trying Out the API

You can try out an API by clicking on the "Try it out" button next to the endpoints.

• Parameters: If an endpoint requires parameters, Swagger UI provides input boxes for you to fill in. This could include path parameters, query strings, headers, or the body of a POST/PUT request.

• Execution: Once you've inputted all the necessary parameters, you can click the "Execute" button to make a live API call. Swagger UI will send the request to the API and display the response directly in the documentation. This includes the response code, response headers, and response body.

Models

Swagger documents the structure of request and response bodies using models. These models define the expected data structure using JSON schema and are extremely helpful in understanding what data to send and expect.