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Templates

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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

Make sure you create a virtual environment, activate it, and install jinja2:

$ pip install jinja2

---> 100%

Using Jinja2Templates

  • Import Jinja2Templates.
  • Create a templates object that you can reuse 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, pass the name of the template, the request object, and a "context" dictionary with key-value pairs to be used inside of the Jinja2 template.
from fastapi import FastAPI, Request
from fastapi.responses import HTMLResponse
from fastapi.staticfiles import StaticFiles
from fastapi.templating import Jinja2Templates

app = FastAPI()

app.mount("/static", StaticFiles(directory="static"), name="static")


templates = Jinja2Templates(directory="templates")


@app.get("/items/{id}", response_class=HTMLResponse)
async def read_item(request: Request, id: str):
    return templates.TemplateResponse(
        request=request, name="item.html", context={"id": id}
    )

Note

Before FastAPI 0.108.0, Starlette 0.29.0, the name was the first parameter.

Also, before that, in previous versions, the request object was passed as part of the key-value pairs in the context for Jinja2.

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, for example:

<html>
<head>
    <title>Item Details</title>
    <link href="{{ url_for('static', path='/styles.css') }}" rel="stylesheet">
</head>
<body>
    <h1><a href="{{ url_for('read_item', id=id) }}">Item ID: {{ id }}</a></h1>
</body>
</html>

Template Context Values

In the HTML that contains:

Item ID: {{ id }}

...it will show the id taken from the "context" dict you passed:

{"id": id}

For example, with an ID of 42, this would render:

Item ID: 42

Template url_for Arguments

You can also use url_for() inside of the template, it takes as arguments the same arguments that would be used by your path operation function.

So, the section with:

<a href="{{ url_for('read_item', id=id) }}">

...will generate a link to the same URL that would be handled by the path operation function read_item(id=id).

For example, with an ID of 42, this would render:

<a href="/items/42">

Templates and static files

You can also use url_for() inside of the template, and use it, for example, with the StaticFiles you mounted with the name="static".

<html>
<head>
    <title>Item Details</title>
    <link href="{{ url_for('static', path='/styles.css') }}" rel="stylesheet">
</head>
<body>
    <h1><a href="{{ url_for('read_item', id=id) }}">Item ID: {{ id }}</a></h1>
</body>
</html>

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

h1 {
    color: green;
}

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.