TrueLayer Data API quickstart sample

Overview

The following Python/Flask sample code shows a very basic integration against TrueLayer's Data API. TrueLayer's Data API will be used to retrieve banking data for a single set of credentials: balance and transaction for each associated account or credit card. All endpoints require authorisation using an JWT access token. To obtain an access token, an end-user has to give you consent to access their details for a given bank using TrueLayer’s Auth Dialog, where they will be asked to enter their details.

This tutorial shows how to do this for a single set of credentials using a very rudimentary in-memory database (a Python dictionary) to store user data.

Registration and client credentials using TL's console

Go to https://console.truelayer.com and sign up: you need to get your client_id and client_secret - these are the keys that will be required to authenticate and interact with our API.

Installation

Requirements

System requirements:

• python 3.7
• pip

Dev environment

Run the following command to reproduce the virtual environment required to run this example:

# We use pipenv to manage dependencies
pip install pipenv
# Recreate a virtual environment with the packages specified in Pipfile.lock
pipenv sync --dev

Launching the application

Install ngrok

To get an access token, your end users will have to go through the Auth Dialog flow: this happens in a pop-up using a Single Page Application hosted on TrueLayer's domain. Once the authentication flow has been successfully completed, you will receive the access token at the callback endpoint you have specified when setting up your application (https://console.truelayer.com/settings/application > Redirect URIs).

For this process to work, your callback endpoint needs to be exposed on the public Internet because it needs to be reachable from our servers.

You can easily achieve this using ngrok, which will setup a local tunnel between your local development environment and a temporary public URL. Ngrok installation instruction can be found here https://ngrok.com/download. If you are running OSX, ngrok can just be installed using Homebrew:

brew cask install ngrok

ngrok can then be run on a local port with:

# 5000 is the local port we are using to run our Flask application
ngrok http 5000

In the output there will be a line with

Forwarding https://<randomid>.ngrok.io -> localhost:5000

Copy the HTTPS URL, add signin_callback (e.g. https://<randomid>.ngrok.io/signin_callback) at the end and add it as redirect URI in TrueLayer console https://console.truelayer.com/settings/application > Redirect URIs.

Setting client keys

In the top folder of this project there is a file called secrets.json: you have to replace the provided client_id, client_secret and redirect_uri with the secrets you got on TrueLayer's console as well as the URL provided by ngrok. Once you have saved your changes, we can move forward

Launching the application

You can now launch the application with a single command:

# FLASK_DEBUG=1 runs the application in the debug mode (more descriptive logs and error messages)
# You can use FLASK_DEBUG=0 to disable it
FLASK_DEBUG=1 FLASK_APP=src/quickstart/app/sign-in.py pipenv run flask run

Visit http://localhost:5000 to try it out.

From TrueLayer’s Auth Dialog, after allowing permissions, 'Mock Bank' can be selected to try out TrueLayer's Data API. Use the following credentials to login:

Username: john
Password: doe