Tutorial: Your First Project

In this tutorial you will create a simple library model, validate it, and generate a Python backend – all within the BESSER Web Modeling Editor. By the end you will understand projects, class diagrams, and code generation.

Note

This tutorial uses the online editor at editor.besser-pearl.org. No installation is required.

Step 1: Create a Project

  1. Open the editor in your browser.

  2. Click File > New / Open / Import Project.

  3. Enter a project name (e.g., “My Library”) and click Create Project.

You are now in the editor with an empty class diagram canvas.

Step 2: Add Classes

Let’s model a simple library with books and authors.

  1. From the Palette on the left, drag a Class element onto the canvas.

  2. Double-click the class to open its properties.

  3. Set the name to Book.

  4. Add attributes (one per line):

    + title: str
+ pages: int
+ price: float

  5. Drag another Class onto the canvas and name it Author.

  6. Add attributes:

    + name: str
+ birth: date

Step 3: Add a Relationship

  1. Click on the Book class.

  2. Drag from a blue connection point on Book to the Author class.

  3. A relationship line appears. Double-click it to edit properties.

  4. Set the Name to written_by.

  5. Set the Type to Bidirectional.

  6. Set the multiplicity: * on the Book side, 1..* on the Author side (a book has one or more authors, an author can write many books).

Step 4: Add an Enumeration

  1. Drag an Enumeration from the palette onto the canvas.

  2. Double-click it and set the name to Genre.

  3. Add values (one per line): Poetry, Thriller, History, Romance.

  4. Now open the Book class properties and add an attribute:

    + genre: Genre

Step 5: Validate Your Model

  1. Click the Quality Check button in the top bar.

  2. If your model has no errors, you will see a success message.

  3. If there are issues (e.g., duplicate class names), the editor will show specific error messages.

Step 6: Generate Code

  1. Click the Generate menu in the top bar.

  2. Select Python Classes from the dropdown.

  3. A .py file is downloaded containing Python class definitions for Book, Author, and Genre.

You can also try other generators:

  • SQL DDL: Generates SQL CREATE TABLE statements.

  • Django: Generates a full Django project with admin panel.

  • Full Web App: Generates a React + FastAPI application (requires a GUI diagram – see GUI Diagrams).

Step 7: Explore Further

Now that you have the basics, try:

  • Adding methods to your classes (e.g., + get_full_name(): str).

  • Adding OCL constraints (drag from palette, write rules like context Book inv: self.pages > 0).

  • Creating an Object Diagram to model specific instances.

  • Switching to a State Machine or Agent Diagram via the left sidebar.

See Diagram Types for detailed guides on each diagram type.