Перейти к содержанию

Middleware

There are several middlewares available provided by Starlette directly.

Read more about them in the FastAPI docs for Middleware.

fastapi.middleware.cors.CORSMiddleware

CORSMiddleware(
    app,
    allow_origins=(),
    allow_methods=("GET"),
    allow_headers=(),
    allow_credentials=False,
    allow_origin_regex=None,
    expose_headers=(),
    max_age=600,
)
PARAMETER DESCRIPTION
app

TYPE: ASGIApp

allow_origins

TYPE: Sequence[str] DEFAULT: ()

allow_methods

TYPE: Sequence[str] DEFAULT: ('GET')

allow_headers

TYPE: Sequence[str] DEFAULT: ()

allow_credentials

TYPE: bool DEFAULT: False

allow_origin_regex

TYPE: str | None DEFAULT: None

expose_headers

TYPE: Sequence[str] DEFAULT: ()

max_age

TYPE: int DEFAULT: 600

Source code in starlette/middleware/cors.py
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
def __init__(
    self,
    app: ASGIApp,
    allow_origins: typing.Sequence[str] = (),
    allow_methods: typing.Sequence[str] = ("GET",),
    allow_headers: typing.Sequence[str] = (),
    allow_credentials: bool = False,
    allow_origin_regex: str | None = None,
    expose_headers: typing.Sequence[str] = (),
    max_age: int = 600,
) -> None:
    if "*" in allow_methods:
        allow_methods = ALL_METHODS

    compiled_allow_origin_regex = None
    if allow_origin_regex is not None:
        compiled_allow_origin_regex = re.compile(allow_origin_regex)

    allow_all_origins = "*" in allow_origins
    allow_all_headers = "*" in allow_headers
    preflight_explicit_allow_origin = not allow_all_origins or allow_credentials

    simple_headers = {}
    if allow_all_origins:
        simple_headers["Access-Control-Allow-Origin"] = "*"
    if allow_credentials:
        simple_headers["Access-Control-Allow-Credentials"] = "true"
    if expose_headers:
        simple_headers["Access-Control-Expose-Headers"] = ", ".join(expose_headers)

    preflight_headers = {}
    if preflight_explicit_allow_origin:
        # The origin value will be set in preflight_response() if it is allowed.
        preflight_headers["Vary"] = "Origin"
    else:
        preflight_headers["Access-Control-Allow-Origin"] = "*"
    preflight_headers.update(
        {
            "Access-Control-Allow-Methods": ", ".join(allow_methods),
            "Access-Control-Max-Age": str(max_age),
        }
    )
    allow_headers = sorted(SAFELISTED_HEADERS | set(allow_headers))
    if allow_headers and not allow_all_headers:
        preflight_headers["Access-Control-Allow-Headers"] = ", ".join(allow_headers)
    if allow_credentials:
        preflight_headers["Access-Control-Allow-Credentials"] = "true"

    self.app = app
    self.allow_origins = allow_origins
    self.allow_methods = allow_methods
    self.allow_headers = [h.lower() for h in allow_headers]
    self.allow_all_origins = allow_all_origins
    self.allow_all_headers = allow_all_headers
    self.preflight_explicit_allow_origin = preflight_explicit_allow_origin
    self.allow_origin_regex = compiled_allow_origin_regex
    self.simple_headers = simple_headers
    self.preflight_headers = preflight_headers

app instance-attribute

app = app

allow_origins instance-attribute

allow_origins = allow_origins

allow_methods instance-attribute

allow_methods = allow_methods

allow_headers instance-attribute

allow_headers = [lower() for h in allow_headers]

allow_all_origins instance-attribute

allow_all_origins = allow_all_origins

allow_all_headers instance-attribute

allow_all_headers = allow_all_headers

preflight_explicit_allow_origin instance-attribute

preflight_explicit_allow_origin = (
    preflight_explicit_allow_origin
)

allow_origin_regex instance-attribute

allow_origin_regex = compiled_allow_origin_regex

simple_headers instance-attribute

simple_headers = simple_headers

preflight_headers instance-attribute

preflight_headers = preflight_headers

is_allowed_origin

is_allowed_origin(origin)
PARAMETER DESCRIPTION
origin

TYPE: str

Source code in starlette/middleware/cors.py
 95
 96
 97
 98
 99
100
101
102
def is_allowed_origin(self, origin: str) -> bool:
    if self.allow_all_origins:
        return True

    if self.allow_origin_regex is not None and self.allow_origin_regex.fullmatch(origin):
        return True

    return origin in self.allow_origins

preflight_response

preflight_response(request_headers)
PARAMETER DESCRIPTION
request_headers

TYPE: Headers

Source code in starlette/middleware/cors.py
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
def preflight_response(self, request_headers: Headers) -> Response:
    requested_origin = request_headers["origin"]
    requested_method = request_headers["access-control-request-method"]
    requested_headers = request_headers.get("access-control-request-headers")

    headers = dict(self.preflight_headers)
    failures = []

    if self.is_allowed_origin(origin=requested_origin):
        if self.preflight_explicit_allow_origin:
            # The "else" case is already accounted for in self.preflight_headers
            # and the value would be "*".
            headers["Access-Control-Allow-Origin"] = requested_origin
    else:
        failures.append("origin")

    if requested_method not in self.allow_methods:
        failures.append("method")

    # If we allow all headers, then we have to mirror back any requested
    # headers in the response.
    if self.allow_all_headers and requested_headers is not None:
        headers["Access-Control-Allow-Headers"] = requested_headers
    elif requested_headers is not None:
        for header in [h.lower() for h in requested_headers.split(",")]:
            if header.strip() not in self.allow_headers:
                failures.append("headers")
                break

    # We don't strictly need to use 400 responses here, since its up to
    # the browser to enforce the CORS policy, but its more informative
    # if we do.
    if failures:
        failure_text = "Disallowed CORS " + ", ".join(failures)
        return PlainTextResponse(failure_text, status_code=400, headers=headers)

    return PlainTextResponse("OK", status_code=200, headers=headers)

simple_response async

simple_response(scope, receive, send, request_headers)
PARAMETER DESCRIPTION
scope

TYPE: Scope

receive

TYPE: Receive

send

TYPE: Send

request_headers

TYPE: Headers

Source code in starlette/middleware/cors.py
142
143
144
async def simple_response(self, scope: Scope, receive: Receive, send: Send, request_headers: Headers) -> None:
    send = functools.partial(self.send, send=send, request_headers=request_headers)
    await self.app(scope, receive, send)

send async

send(message, send, request_headers)
PARAMETER DESCRIPTION
message

TYPE: Message

send

TYPE: Send

request_headers

TYPE: Headers

Source code in starlette/middleware/cors.py
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
async def send(self, message: Message, send: Send, request_headers: Headers) -> None:
    if message["type"] != "http.response.start":
        await send(message)
        return

    message.setdefault("headers", [])
    headers = MutableHeaders(scope=message)
    headers.update(self.simple_headers)
    origin = request_headers["Origin"]
    has_cookie = "cookie" in request_headers

    # If request includes any cookie headers, then we must respond
    # with the specific origin instead of '*'.
    if self.allow_all_origins and has_cookie:
        self.allow_explicit_origin(headers, origin)

    # If we only allow specific origins, then we have to mirror back
    # the Origin header in the response.
    elif not self.allow_all_origins and self.is_allowed_origin(origin=origin):
        self.allow_explicit_origin(headers, origin)

    await send(message)

allow_explicit_origin staticmethod

allow_explicit_origin(headers, origin)
PARAMETER DESCRIPTION
headers

TYPE: MutableHeaders

origin

TYPE: str

Source code in starlette/middleware/cors.py
169
170
171
172
@staticmethod
def allow_explicit_origin(headers: MutableHeaders, origin: str) -> None:
    headers["Access-Control-Allow-Origin"] = origin
    headers.add_vary_header("Origin")

It can be imported from fastapi:

from fastapi.middleware.cors import CORSMiddleware

fastapi.middleware.gzip.GZipMiddleware

GZipMiddleware(app, minimum_size=500, compresslevel=9)
PARAMETER DESCRIPTION
app

TYPE: ASGIApp

minimum_size

TYPE: int DEFAULT: 500

compresslevel

TYPE: int DEFAULT: 9

Source code in starlette/middleware/gzip.py
10
11
12
13
def __init__(self, app: ASGIApp, minimum_size: int = 500, compresslevel: int = 9) -> None:
    self.app = app
    self.minimum_size = minimum_size
    self.compresslevel = compresslevel

app instance-attribute

app = app

minimum_size instance-attribute

minimum_size = minimum_size

compresslevel instance-attribute

compresslevel = compresslevel

It can be imported from fastapi:

from fastapi.middleware.gzip import GZipMiddleware

fastapi.middleware.httpsredirect.HTTPSRedirectMiddleware

HTTPSRedirectMiddleware(app)
PARAMETER DESCRIPTION
app

TYPE: ASGIApp

Source code in starlette/middleware/httpsredirect.py
7
8
def __init__(self, app: ASGIApp) -> None:
    self.app = app

app instance-attribute

app = app

It can be imported from fastapi:

from fastapi.middleware.httpsredirect import HTTPSRedirectMiddleware

fastapi.middleware.trustedhost.TrustedHostMiddleware

TrustedHostMiddleware(
    app, allowed_hosts=None, www_redirect=True
)
PARAMETER DESCRIPTION
app

TYPE: ASGIApp

allowed_hosts

TYPE: Sequence[str] | None DEFAULT: None

www_redirect

TYPE: bool DEFAULT: True

Source code in starlette/middleware/trustedhost.py
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
def __init__(
    self,
    app: ASGIApp,
    allowed_hosts: typing.Sequence[str] | None = None,
    www_redirect: bool = True,
) -> None:
    if allowed_hosts is None:
        allowed_hosts = ["*"]

    for pattern in allowed_hosts:
        assert "*" not in pattern[1:], ENFORCE_DOMAIN_WILDCARD
        if pattern.startswith("*") and pattern != "*":
            assert pattern.startswith("*."), ENFORCE_DOMAIN_WILDCARD
    self.app = app
    self.allowed_hosts = list(allowed_hosts)
    self.allow_any = "*" in allowed_hosts
    self.www_redirect = www_redirect

app instance-attribute

app = app

allowed_hosts instance-attribute

allowed_hosts = list(allowed_hosts)

allow_any instance-attribute

allow_any = '*' in allowed_hosts

www_redirect instance-attribute

www_redirect = www_redirect

It can be imported from fastapi:

from fastapi.middleware.trustedhost import TrustedHostMiddleware

fastapi.middleware.wsgi.WSGIMiddleware

WSGIMiddleware(app)
PARAMETER DESCRIPTION
app

TYPE: Callable[..., Any]

Source code in starlette/middleware/wsgi.py
74
75
def __init__(self, app: typing.Callable[..., typing.Any]) -> None:
    self.app = app

app instance-attribute

app = app

It can be imported from fastapi:

from fastapi.middleware.wsgi import WSGIMiddleware