Templates

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You can use any template engine you want with FastAPI.

A common election 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 jinja2:

  1. $ pip install jinja2
  3. ---> 100%

If you need to also serve static files (as in this example), install aiofiles:

  1. $ pip install aiofiles
  3. ---> 100%

Using Jinja2Templates

  • Import Jinja2Templates.
  • Create a templates object that you can re-use later.
  • Declare a Request parameter in the path operation that will return a template.
  • Use the templates you created to render and return a TemplateResponse, passing the request as one of the key-value pairs in the Jinja2 “context”.
  1. from fastapi import FastAPI, Request
  2. from fastapi.responses import HTMLResponse
  3. from fastapi.staticfiles import StaticFiles
  4. from fastapi.templating import Jinja2Templates
  6. app = FastAPI()
  8. app.mount("/static", StaticFiles(directory="static"), name="static")
  11. templates = Jinja2Templates(directory="templates")
  14. @app.get("/items/{id}", response_class=HTMLResponse)
  15. async def read_item(request: Request, id: str):
  16.     return templates.TemplateResponse("item.html", {"request": request, "id": id})

Note

Notice that you have to pass the request as part of the key-value pairs in the context for Jinja2. So, you also have to declare it in your path operation.

Tip

By declaring response_class=HTMLResponse the docs UI will be able to know that the response will be HTML.

Technical Details

You could also use from starlette.templating import Jinja2Templates.

FastAPI provides the same starlette.templating as fastapi.templating just as a convenience for you, the developer. But most of the available responses come directly from Starlette. The same with Request and StaticFiles.

Writing templates

Then you can write a template at templates/item.html with:

  1. <html>
  2. <head>
  3.     <title>Item Details</title>
  4.     <link href="{{ url_for('static', path='/styles.css') }}" rel="stylesheet">
  5. </head>
  6. <body>
  7.     <h1>Item ID: {{ id }}</h1>
  8. </body>
  9. </html>

It will show the id taken from the “context” dict you passed:

  1. {"request": request, "id": id}

Templates and static files

And you can also use url_for() inside of the template, and use it, for example, with the StaticFiles you mounted.

  1. <html>
  2. <head>
  3.     <title>Item Details</title>
  4.     <link href="{{ url_for('static', path='/styles.css') }}" rel="stylesheet">
  5. </head>
  6. <body>
  7.     <h1>Item ID: {{ id }}</h1>
  8. </body>
  9. </html>

In this example, it would link to a CSS file at static/styles.css with:

  1. h1 {
  2.     color: green;
  3. }

And because you are using StaticFiles, that CSS file would be served automatically by your FastAPI application at the URL /static/styles.css.

More details

For more details, including how to test templates, check Starlette’s docs on templates.