**FastAPI** provides a convenience tool to structure your application while keeping all the flexibility.

/// info

If you come from Flask, this would be the equivalent of Flask's Blueprints.

///

## An example file structure { #an-example-file-structure }

Let's say you have a file structure like this:

```
.
├── app
│   ├── __init__.py
│   ├── main.py
│   ├── dependencies.py
│   └── routers
│   │   ├── __init__.py

certs-dir: '/home/user/.minio/certs/'
pools: # Specify the nodes and drives with pools
  -
        - 'https://server-example-pool1:9000/mnt/disk{1...4}/'
        - 'https://server1-pool1:9000/mnt/disk{1...4}/'
        - 'https://server3-pool1:9000/mnt/disk{1...4}/'
        - 'https://server4-pool1:9000/mnt/disk{1...4}/'
  -
        - 'https://server-example-pool2:9000/mnt/disk{1...4}/'
        - 'https://server1-pool2:9000/mnt/disk{1...4}/'

    ;

    open fun encode(codePoint: Int): String = throw UnsupportedOperationException()
  }

  enum class Component {
    USER {
      override fun urlString(value: String): String = "http://$value@example.com/"

      override fun encodedValue(url: HttpUrl): String = url.encodedUsername

      override operator fun set(
        builder: HttpUrl.Builder,
        value: String,
      ) {

        // Test when only baseDn is set
        ComponentUtil.setFessConfig(new FessConfig.SimpleImpl() {
            @Override
            public String getLdapBaseDn() {
                return "dc=example,dc=com";
            }

            @Override
            public String getLdapAccountFilter() {
                return "";
            }
        });

        // Test registerSmbURLHandler when java.protocol.handler.pkgs does not contain "jcifs"
        System.setProperty("java.protocol.handler.pkgs", "com.example");
        SingletonContext.registerSmbURLHandler();
        assertEquals("com.example|jcifs", System.getProperty("java.protocol.handler.pkgs"));
    }

    @Test
    void testRegisterSmbURLHandlerWhenPkgsAlreadyContainsJcifs() {

import javax.security.auth.callback.UnsupportedCallbackException
import okhttp3.OkHttpClient
import okhttp3.Request
import okhttp3.internal.SuppressSignatureCheck
import okhttp3.internal.platform.Platform

/**
 * Example of using a hardware key to perform client auth.
 * Prefer recent JDK builds, and results are temperamental to slight environment changes.
 * Different instructions and configuration may be required for other hardware devices.
 *

For example, there's an official <a href="https://hub.docker.com/_/python" class="external-link" target="_blank">Python Image</a>.

And there are many other images for different things like databases, for example for:

* <a href="https://hub.docker.com/_/postgres" class="external-link" target="_blank">PostgreSQL</a>

The `TestClient` is based on <a href="https://www.python-httpx.org" class="external-link" target="_blank">HTTPX</a>, and luckily, we can use it directly to test the API.

## Example { #example }

For a simple example, let's consider a file structure similar to the one described in [Bigger Applications](../tutorial/bigger-applications.md){.internal-link target=_blank} and [Testing](../tutorial/testing.md){.internal-link target=_blank}:

This document focuses on showing a working example on how to use Object Lambda with MinIO, you must have [MinIO deployed in your environment](https://docs.min.io/community/minio-object-store/operations/installation.html) before you can start using external lambda functions. You also must install Python version 3.8 or later for the lambda handlers to work.

## Example Lambda handler

Install the necessary dependencies.
```sh

# Query Parameters and String Validations { #query-parameters-and-string-validations }

**FastAPI** allows you to declare additional information and validation for your parameters.

Let's take this application as example:

{* ../../docs_src/query_params_str_validations/tutorial001_py310.py hl[7] *}