And the rest will be handled by **FastAPI**.

If you run it and go to <a href="http://localhost:8000/v1/" class="external-link" target="_blank">http://localhost:8000/v1/</a> you will see the response from Flask:

```txt
Hello, World from Flask!
```

And if you go to <a href="http://localhost:8000/v2" class="external-link" target="_blank">http://localhost:8000/v2</a> you will see the response from FastAPI:

                            "description": "Not Found",
                            "content": {
                                "application/json": {
                                    "schema": {"$ref": "#/components/schemas/Message"}
                                }
                            },
                        },
                        "200": {
                            "description": "Successful Response",

                            "content": {
                                "application/json": {
                                    "schema": {
                                        "$ref": "#/components/schemas/HTTPValidationError"
                                    }
                                }
                            },
                        },
                    },

				)

				for _, ref := range rel.References {
					if ref.OwnPrimaryKey {
						foreignFields = append(foreignFields, ref.PrimaryKey)
						relForeignKeys = append(relForeignKeys, ref.ForeignKey.DBName)
					} else if ref.PrimaryValue != "" {
						queryConds = append(queryConds, clause.Eq{
							Column: clause.Column{Table: rel.JoinTable.Table, Name: ref.ForeignKey.DBName},
							Value:  ref.PrimaryValue,

          <description>
            Type of toolchain:&lt;ul>
            &lt;li>{@code jdk} for &lt;a
            href="https://maven.apache.org/plugins/maven-toolchains-plugin/toolchains/jdk.html">JDK Standard Toolchain&lt;/a>,&lt;/li>
            &lt;li>other value for &lt;a
            href="https://maven.apache.org/plugins/maven-toolchains-plugin/toolchains/custom.html">Custom Toolchain&lt;/a>&lt;/li>
            &lt;/ul>

                                    "schema": {
                                        "title": "Response Items-Get Items",
                                        "type": "array",
                                        "items": {"$ref": "#/components/schemas/Item"},
                                    }
                                }
                            },
                        }
                    },
                },

                                </la:info>
                                <la:errors/>
                            </div>
                            <a role="button" data-toggle="collapse" href="#listSearchForm" aria-expanded="false"
                               aria-controls="listSearchForm"><i class="fas fa-search" aria-hidden="true"></i></a>

Der `TestClient` basiert auf <a href="https://www.python-httpx.org" class="external-link" target="_blank">HTTPX</a> und glücklicherweise können wir es direkt verwenden, um die API zu testen.

## Beispiel { #example }

{* ../../docs_src/middleware/tutorial001_py39.py hl[8:9,11,14] *}

/// tip | Consejo

Ten en cuenta que los custom proprietary headers se pueden añadir <a href="https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers" class="external-link" target="_blank">usando el prefijo `X-`</a>.

                    "required": ["item", "item2"],
                    "type": "object",
                    "properties": {
                        "item": {"$ref": "#/components/schemas/Item"},
                        "item2": {"$ref": "#/components/schemas/Item"},
                    },
                },
                "HTTPValidationError": {
                    "title": "HTTPValidationError",