# Debugging { #debugging }

You can connect the debugger in your editor, for example with Visual Studio Code or PyCharm.

## Call `uvicorn` { #call-uvicorn }

In your FastAPI application, import and run `uvicorn` directly:

{* ../../docs_src/debugging/tutorial001_py39.py hl[1,15] *}

### About `__name__ == "__main__"` { #about-name-main }

                                "content": {"application/json": {"schema": {}}},
                            },
                            "422": {
                                "description": "Validation Error",
                                "content": {
                                    "application/json": {
                                        "schema": {

{* ../../docs_src/behind_a_proxy/tutorial004_py39.py hl[9] *}

and then it won't include it in the OpenAPI schema.

## Mounting a sub-application { #mounting-a-sub-application }

If you need to mount a sub-application (as described in [Sub Applications - Mounts](sub-applications.md){.internal-link target=_blank}) while also using a proxy with `root_path`, you can do it normally, as you would expect.

            "description": "Just kiddin', no magic here. ✨",
        },
    }


@app.post(
    "/items/",
    openapi_extra={
        "requestBody": {
            "content": {
                "application/json": {
                    "schema": {
                        "required": ["name", "price"],
                        "type": "object",
                        "properties": {

                "get": {
                    "responses": {
                        "200": {
                            "description": "Successful Response",
                            "content": {"application/json": {"schema": {}}},
                        }
                    },
                    "summary": "Read Items",
                    "operationId": "read_items_items__get",
                }
            }

                                "content": {"application/json": {"schema": {}}},
                            },
                            "422": {
                                "description": "Validation Error",
                                "content": {
                                    "application/json": {
                                        "schema": {

                        "responses": {
                            "200": {
                                "description": "Successful Response",
                                "content": {
                                    "application/json": {
                                        "schema": {
                                            "$ref": "#/components/schemas/UserOut"
                                        }
                                    }

You can use any template engine you want with **FastAPI**.

A common choice is Jinja2, the same one used by Flask and other tools.

There are utilities to configure it easily that you can use directly in your **FastAPI** application (provided by Starlette).

## Install dependencies { #install-dependencies }

Make sure you create a [virtual environment](../virtual-environments.md){.internal-link target=_blank}, activate it, and install `jinja2`:

                "get": {
                    "responses": {
                        "200": {
                            "description": "Successful Response",
                            "content": {"application/json": {"schema": {}}},
                        }
                    },
                    "summary": "Read Items",
                    "operationId": "read_items",
                }
            }
        },

    assertThat(body!!.contentType().toString()).isEqualTo(
      "application/x-www-form-urlencoded; charset=utf-8",
    )
    assertThat(bodyAsString(body)).isEqualTo("foo")
  }

  @Test
  fun contentTypeHeader() {
    val request =
      fromArgs(
        "-d",
        "foo",
        "-H",
        "Content-Type: application/json",
        "http://example.com",
      ).createRequest()