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How to create REST API using Total.js LessCode

In this tutorial, we will walk through the process of building a REST API using Total.js LessCode, which offers a visual programming interface. We will cover how to handle requests and responses using Total.js LessCode.

How to create REST API using Total.js LessCode

In this tutorial, we will walk through the process of building a REST API using Total.js LessCode, which offers a visual programming interface. We will cover how to handle requests and responses using Total.js LessCode.

What is Total.js LessCode

Total.js LessCode is an application that simplifies and enables the fast building of APIs, like its name suggests, with less coding. The app uses the Total.js Flow engine, so it can take advantage of all its benefits. Total.js Flow offers a visual programming interface.


First of all, make sure you have at least version 19 of Node.js installed. If not, proceed to install Node.js.

You can install the application either manually or using Docker, I will be proceeding with the manual installation. However, if you prefer to use Docker, instructions for Docker installation can be found here:

Manual installation:

To install Total.js LessCode manually, visit the GitHub repository Total.js LessCode and either download the code manually or clone the repository using your terminal. Use the following command:

This command will download the LessCode source code to your computer and save it to a lesscode-app folder. Open the lesscode-app directory in the code editor you prefer and install the dependencies:

With the dependencies installed, your Total.js LessCode application is now successfully set up, and we are ready to run the application.

Running the application

Run npm start in the terminal to run the app. Be sure you are in lesscode-app folder.

The LessCode app is now running on your local machine.

The app will automatically generate your token. This token is essential for accessing the Flow editor. You will see a URL in your terminal or command-line output. It will look like this:

Screenshot 2024-03-28 at 11.46.30.png

Simply copy this URL into your web browser to access the Flow editor, and we are ready to start editing in the visual programming interface.

You should now see one flowstream called api.

What are flowstreams? Flowstream is simply a JSON file that stores all changes and information about the visual interface you utilize. All components you use, their configurations, positions, and many more...

You can have multiple flowstreams in your app.

In the LessCode app, flowstreams are located in the /databases/flowstreams/{name}.json directory, where {name} represents the specific flowstream file name.

Screenshot 2024-03-28 at 12.10.51.png

Now that we have a basic understanding of flowstreams, let's see them in action. Start by clicking on the api flowstream in the LessCode app. Here, you will find the welcome endpoint. Next, open a new tab in your browser and navigate to http://localhost:8000/. If a welcome message appears, this confirms that everything is working correctly. Additionally, you'll notice a visual indication within the flowstream each time the endpoint is triggered.

Building REST API

To begin building our REST API, we'll start by creating a new flowstream file users.json in the /databases/flowstreams/ directory. Then, add the following JSON structure to this file:

Next, open the config file in the root directory of the app and just save it. Now navigate to and you should see users flowstream. If you don't see it, try reloading the page.

Screenshot 2024-03-28 at 13.32.34.png

Now click on users flowstream. On the left side of the side panel, press the download button to download the components we will need for our API.

  • Route for defining routes
  • Action for creating CRUD API and validations
  • Response for handling responses
  • Print for printing data

Firstly, we need to set up a database. In Total.js, we use the Total.js QueryBuilder for database connectivity. For this example, I'll be utilizing PostgreSQL.

To connect the application to the database, first add your database connection string to the config file in the root directory of your project. It should look like this:


To initialize the database connection. On the top of the definitions/init.js add the following code:

require('querybuilderpg').init('default', CONF.database);

Use this SQL command to create a table named 'tbl_users' with three fields: 'id', 'name', and 'age':

Adding a new user to the database:

In our users flowstream, drag and drop components on the main area of Flow interface. And connect them, like in the picture below:

Screenshot 2024-03-28 at 15.06.09.png

Double-click on component Route and configure it like on the picture below. In this component, you can set the method of request and multiple parameters, such as a timeout, a request limit if you need to be authenticated or not, and more... Character # in relative url means the ID of flowstream so if you set an ID like me, users, this will be transferred from /#/create to /users/create. This helps in creating clear and meaningful paths for your API endpoints.

Screenshot 2024-03-28 at 15.29.41.png

Next, we need to configure component Action and set the expected payload. This component creates similar functionality as Total.js Actions. You will find all supported data types. In the payload schema, the character * means that a value is required. This component also supports await keyword out of the box.

Screenshot 2024-03-28 at 15.13.35.png

Now click on the button script in the Action component. Here, you can write Javascript code mostly for database queries. On the object called model, our payloads, with name and age, are attached, so we just generate a unique ID for the user, insert it into the database, and we can call the endpoint.

Screenshot 2024-03-28 at 15.34.21.png

Use a tool like Postman to test the API by sending requests.

Screenshot 2024-04-02 at 12.37.55.png

Once you send the request, you should be able to see the expected response displayed in the print component.

Screenshot 2024-04-02 at 09.12.53.png

We can add second user with values for example : { name: 'John', age: 23 }.

Now we have 2 users in the database:

Screenshot 2024-04-02 at 12.43.32.png

Getting a list of users

To create a new route, we need to drag new components to the main area of Flow and configure components

Screenshot 2024-04-02 at 09.45.11.png

Hit the endpoint with postman or some other testing API tool:

After you send a request to the new endpoint, you should see a list of users in the print component.

Screenshot 2024-04-02 at 09.46.11.png

Getting one user

Drag new components to the main area of Flow and configure them. First of all, we need to set up a dynamic parameter for the URL in the component Route.

Screenshot 2024-04-02 at 10.06.12.png

Then, in component Action, set up the Params schema as required and expected type of dynamic value.

Screenshot 2024-04-02 at 10.07.07.png

Next, create a database query in component Action. Dynamic parameters are attached to the $.params object.

Screenshot 2024-04-02 at 13.02.32.png

Now, when you send a request with the ID of any user in our database, if the ID matches the user's ID in the database, we get his data, otherwise, we get an error.

Screenshot 2024-04-02 at 13.06.32.png

If an error occurs:

Screenshot 2024-04-02 at 10.22.32.png

Updating a user

Drag new components to the main area of Flow interface and configure them.

Screenshot 2024-04-02 at 10.48.01.png

Hit the endpoint with the ID of the user you want to update:

When you check the user in the database, you can see the user was updated:

Screenshot 2024-04-02 at 13.21.07.png

Removing a user

Drag new components to the main area of Flow and configure them.

Screenshot 2024-04-02 at 10.28.51.png

By hitting endpoint with ID of user. User will be removed from database:

A useful tip at the end

If you check the 'Auto HTTP response' option in the Action component, there's no need for a separate response component, everything will still work.

Screenshot 2024-04-02 at 13.30.44.png

You will need only Route and Action components:

Screenshot 2024-04-02 at 13.38.44.png


That’s it! Now we can test all our endpoints with Postman by sending requests to each route and verifying that the correct response is returned. This is a basic example of building a REST API with Total.js LessCode. From here, we can continue to expand our API by adding more routes and more flowstreams.