# Tutorial - User Guide { #tutorial-user-guide }

This tutorial shows you how to use **FastAPI** with most of its features, step by step.

Each section gradually builds on the previous ones, but it's structured to separate topics, so that you can go directly to any specific one to solve your specific API needs.

It is also built to work as a future reference so you can come back and see exactly what you need.

## Run the code { #run-the-code }

    //                                                                      ==============
    /**
     * Show the index page.
     * @return The HTML response.
     */
    @Execute
    @Secured({ ROLE, ROLE + VIEW })
    public HtmlResponse index() {
        return asListHtml();
    }

    /**
     * Show the list page.
     * @param pageNumber The page number.
     * @param form The search form.

Now you can start your app and go to <a href="http://127.0.0.1:8000/docs" class="external-link" target="_blank">http://127.0.0.1:8000/docs</a>.

You will see your docs including a "Callbacks" section for your *path operation* that shows how the *external API* should look like:

            - .github/workflows/build-docs.yml
            - .github/workflows/deploy-docs.yml
  langs:
    needs:
      - changes
    runs-on: ubuntu-latest
    outputs:
      langs: ${{ steps.show-langs.outputs.langs }}
    steps:
      - uses: actions/checkout@v5
      - name: Set up Python
        uses: actions/setup-python@v5
        with:
          python-version: "3.11"
      - name: Setup uv

# Exceptions - `HTTPException` and `WebSocketException`

These are the exceptions that you can raise to show errors to the client.

When you raise an exception, as would happen with normal Python, the rest of the execution is aborted. This way you can raise these exceptions from anywhere in the code to abort a request and show the error to the client.

You can use:

* `HTTPException`
* `WebSocketException`

        }

        if (typeof options.ranges === 'object')
            this.container.addClass('show-ranges');

        if (this.singleDatePicker) {
            this.container.addClass('single');
            this.container.find('.drp-calendar.left').addClass('single');
            this.container.find('.drp-calendar.left').show();
            this.container.find('.drp-calendar.right').hide();

* 🐛 Fix edge case with repeated aliases names not shown in OpenAPI. PR [#2351](https://github.com/tiangolo/fastapi/pull/2351) by [@klaa97](https://github.com/klaa97).

    //                                                                      Search Execute
    //                                                                      ==============
    /**
     * Shows the main elevate word management page.
     *
     * @return HTML response for the elevate word list page
     */
    @Execute
    @Secured({ ROLE, ROLE + VIEW })
    public HtmlResponse index() {

    //                                                                      ==============
    /**
     * Show the index page.
     * @return The HTML response.
     */
    @Execute
    @Secured({ ROLE, ROLE + VIEW })
    public HtmlResponse index() {
        return asListHtml();
    }

    /**
     * Show the list page.
     * @param pageNumber The page number.
     * @param form The search form.

    //                                                                      ==============
    /**
     * Show the index page.
     * @return The HTML response.
     */
    @Execute
    @Secured({ ROLE, ROLE + VIEW })
    public HtmlResponse index() {
        saveToken();
        return asListHtml();
    }

    /**
     * Show the list page.
     * @param pageNumber The page number.
     * @param form The search form.