fastapi

This skill should be triggered when:

• Working with fastapi
• Asking about fastapi features or APIs
• Implementing fastapi solutions
• Debugging fastapi code
• Learning fastapi best practices

Common Patterns

Pattern 1: This includes, for example:

```

BackgroundTasks

```

Pattern 2: Info To use forms, first install python-multipart. Make sure you create a virtual environment, activate it, and then install it, for example: $ pip install python-multipart

```

python-multipart

```

Pattern 3: Make sure you create a virtual environment, activate it, and then install it, for example:

```

$ pip install python-multipart

```

Pattern 4: fastapi.FastAPI ¶ FastAPI( , debug=False, routes=None, title="FastAPI", summary=None, description="", version="0.1.0", openapi_url="/openapi.json", openapi_tags=None, servers=None, dependencies=None, default_response_class=Default(JSONResponse), redirect_slashes=True, docs_url="/docs", redoc_url="/redoc", swagger_ui_oauth2_redirect_url="/docs/oauth2-redirect", swagger_ui_init_oauth=None, middleware=None, exception_handlers=None, on_startup=None, on_shutdown=None, lifespan=None, terms_of_service=None, contact=None, license_info=None, openapi_prefix="", root_path="", root_path_in_servers=True, responses=None, callbacks=None, webhooks=None, deprecated=None, include_in_schema=True, swagger_ui_parameters=None, generate_unique_id_function=Default(generate_unique_id), separate_input_output_schemas=True, openapi_external_docs=None, extra ) Bases: Starlette FastAPI app class, the main entrypoint to use FastAPI. Read more in the FastAPI docs for First Steps. Example¶ from fastapi import FastAPI app = FastAPI() PARAMETER DESCRIPTION debug Boolean indicating if debug tracebacks should be returned on server errors. Read more in the Starlette docs for Applications. TYPE: bool DEFAULT: False routes Note: you probably shouldn't use this parameter, it is inherited from Starlette and supported for compatibility. A list of routes to serve incoming HTTP and WebSocket requests. TYPE: Optional[List[BaseRoute]] DEFAULT: None title The title of the API. It will be added to the generated OpenAPI (e.g. visible at /docs). Read more in the FastAPI docs for Metadata and Docs URLs. Example from fastapi import FastAPI app = FastAPI(title="ChimichangApp") TYPE: str DEFAULT: 'FastAPI' summary A short summary of the API. It will be added to the generated OpenAPI (e.g. visible at /docs). Read more in the FastAPI docs for Metadata and Docs URLs. Example from fastapi import FastAPI app = FastAPI(summary="Deadpond's favorite app. Nuff said.") TYPE: Optional[str] DEFAULT: None description A description of the API. Supports Markdown (using CommonMark syntax). It will be added to the generated OpenAPI (e.g. visible at /docs). Read more in the FastAPI docs for Metadata and Docs URLs. Example from fastapi import FastAPI app = FastAPI( description=""" ChimichangApp API helps you do awesome stuff. 🚀 ## Items You can read items. ## Users You will be able to: Create users (_not implemented_). Read users (_not implemented_). """ ) TYPE: str DEFAULT: '' version The version of the API. Note This is the version of your application, not the version of the OpenAPI specification nor the version of FastAPI being used. It will be added to the generated OpenAPI (e.g. visible at /docs). Read more in the FastAPI docs for Metadata and Docs URLs. Example from fastapi import FastAPI app = FastAPI(version="0.0.1") TYPE: str DEFAULT: '0.1.0' openapi_url The URL where the OpenAPI schema will be served from. If you set it to None, no OpenAPI schema will be served publicly, and the default automatic endpoints /docs and /redoc will also be disabled. Read more in the FastAPI docs for Metadata and Docs URLs. Example from fastapi import FastAPI app = FastAPI(openapi_url="/api/v1/openapi.json") TYPE: Optional[str] DEFAULT: '/openapi.json' openapi_tags A list of tags used by OpenAPI, these are the same tags you can set in the path operations, like: @app.get("/users/", tags=["users"]) @app.get("/items/", tags=["items"]) The order of the tags can be used to specify the order shown in tools like Swagger UI, used in the automatic path /docs. It's not required to specify all the tags used. The tags that are not declared MAY be organized randomly or based on the tools' logic. Each tag name in the list MUST be unique. The value of each item is a dict containing: name: The name of the tag. description: A short description of the tag. CommonMark syntax MAY be used for rich text representation. externalDocs: Additional external documentation for this tag. If provided, it would contain a dict with: description: A short description of the target documentation. CommonMark syntax MAY be used for rich text representation. url: The URL for the target documentation. Value MUST be in the form of a URL. Read more in the FastAPI docs for Metadata and Docs URLs. Example from fastapi import FastAPI tags_metadata = [ { "name": "users", "description": "Operations with users. The login logic is also here.", }, { "name": "items", "description": "Manage items. So _fancy_ they have their own docs.", "externalDocs": { "description": "Items external docs", "url": "https://fastapi.tiangolo.com/", }, }, ] app = FastAPI(openapi_tags=tags_metadata) TYPE: Optional[List[Dict[str, Any]]] DEFAULT: None servers A list of dicts with connectivity information to a target server. You would use it, for example, if your application is served from different domains and you want to use the same Swagger UI in the browser to interact with each of them (instead of having multiple browser tabs open). Or if you want to leave fixed the possible URLs. If the servers list is not provided, or is an empty list, the servers property in the generated OpenAPI will be: a dict with a url value of the application's mounting point (root_path) if it's different from /. otherwise, the servers property will be omitted from the OpenAPI schema. Each item in the list is a dict containing: url: A URL to the target host. This URL supports Server Variables and MAY be relative, to indicate that the host location is relative to the location where the OpenAPI document is being served. Variable substitutions will be made when a variable is named in {brackets}. description: An optional string describing the host designated by the URL. CommonMark syntax MAY be used for rich text representation. variables: A dict between a variable name and its value. The value is used for substitution in the server's URL template. Read more in the FastAPI docs for Behind a Proxy. Example from fastapi import FastAPI app = FastAPI( servers=[ {"url": "https://stag.example.com", "description": "Staging environment"}, {"url": "https://prod.example.com", "description": "Production environment"}, ] ) TYPE: Optional[List[Dict[str, Union[str, Any]]]] DEFAULT: None dependencies A list of global dependencies, they will be applied to each path operation, including in sub-routers. Read more about it in the FastAPI docs for Global Dependencies. Example from fastapi import Depends, FastAPI from .dependencies import func_dep_1, func_dep_2 app = FastAPI(dependencies=[Depends(func_dep_1), Depends(func_dep_2)]) TYPE: Optional[Sequence[Depends]] DEFAULT: None default_response_class The default response class to be used. Read more in the FastAPI docs for Custom Response - HTML, Stream, File, others. Example from fastapi import FastAPI from fastapi.responses import ORJSONResponse app = FastAPI(default_response_class=ORJSONResponse) TYPE: Type[Response] DEFAULT: Default(JSONResponse) redirect_slashes Whether to detect and redirect slashes in URLs when the client doesn't use the same format. Example from fastapi import FastAPI app = FastAPI(redirect_slashes=True) # the default @app.get("/items/") async def read_items(): return [{"item_id": "Foo"}] With this app, if a client goes to /items (without a trailing slash), they will be automatically redirected with an HTTP status code of 307 to /items/. TYPE: bool DEFAULT: True docs_url The path to the automatic interactive API documentation. It is handled in the browser by Swagger UI. The default URL is /docs. You can disable it by setting it to None. If openapi_url is set to None, this will be automatically disabled. Read more in the FastAPI docs for Metadata and Docs URLs. Example from fastapi import FastAPI app = FastAPI(docs_url="/documentation", redoc_url=None) TYPE: Optional[str] DEFAULT: '/docs' redoc_url The path to the alternative automatic interactive API documentation provided by ReDoc. The default URL is /redoc. You can disable it by setting it to None. If openapi_url is set to None, this will be automatically disabled. Read more in the FastAPI docs for Metadata and Docs URLs. Example from fastapi import FastAPI app = FastAPI(docs_url="/documentation", redoc_url="redocumentation") TYPE: Optional[str] DEFAULT: '/redoc' swagger_ui_oauth2_redirect_url The OAuth2 redirect endpoint for the Swagger UI. By default it is /docs/oauth2-redirect. This is only used if you use OAuth2 (with the "Authorize" button) with Swagger UI. TYPE: Optional[str] DEFAULT: '/docs/oauth2-redirect' swagger_ui_init_oauth OAuth2 configuration for the Swagger UI, by default shown at /docs. Read more about the available configuration options in the Swagger UI docs. TYPE: Optional[Dict[str, Any]] DEFAULT: None middleware List of middleware to be added when creating the application. In FastAPI you would normally do this with app.add_middleware() instead. Read more in the FastAPI docs for Middleware. TYPE: Optional[Sequence[Middleware]] DEFAULT: None exception_handlers A dictionary with handlers for exceptions. In FastAPI, you would normally use the decorator @app.exception_handler(). Read more in the FastAPI docs for Handling Errors. TYPE: Optional[Dict[Union[int, Type[Exception]], Callable[[Request, Any], Coroutine[Any, Any, Response]]]] DEFAULT: None on_startup A list of startup event handler functions. You should instead use the lifespan handlers. Read more in the FastAPI docs for lifespan. TYPE: Optional[Sequence[Callable[[], Any]]] DEFAULT: None on_shutdown A list of shutdown event handler functions. You should instead use the lifespan handlers. Read more in the FastAPI docs for lifespan. TYPE: Optional[Sequence[Callable[[], Any]]] DEFAULT: None lifespan A Lifespan context manager handler. This replaces startup and shutdown functions with a single context manager. Read more in the FastAPI docs for lifespan. TYPE: Optional[Lifespan[AppType]] DEFAULT: None terms_of_service A URL to the Terms of Service for your API. It will be added to the generated OpenAPI (e.g. visible at /docs). Read more at the FastAPI docs for Metadata and Docs URLs. Example app = FastAPI(terms_of_service="http://example.com/terms/") TYPE: Optional[str] DEFAULT: None contact A dictionary with the contact information for the exposed API. It can contain several fields. name: (str) The name of the contact person/organization. url: (str) A URL pointing to the contact information. MUST be in the format of a URL. email: (str) The email address of the contact person/organization. MUST be in the format of an email address. It will be added to the generated OpenAPI (e.g. visible at /docs). Read more at the FastAPI docs for Metadata and Docs URLs. Example app = FastAPI( contact={ "name": "Deadpoolio the Amazing", "url": "http://x-force.example.com/contact/", "email": "dp@x-force.example.com", } ) TYPE: Optional[Dict[str, Union[str, Any]]] DEFAULT: None license_info A dictionary with the license information for the exposed API. It can contain several fields. name: (str) REQUIRED (if a license_info is set). The license name used for the API. identifier: (str) An SPDX license expression for the API. The identifier field is mutually exclusive of the url field. Available since OpenAPI 3.1.0, FastAPI 0.99.0. url: (str) A URL to the license used for the API. This MUST be the format of a URL. It will be added to the generated OpenAPI (e.g. visible at /docs). Read more at the FastAPI docs for Metadata and Docs URLs. Example app = FastAPI( license_info={ "name": "Apache 2.0", "url": "https://www.apache.org/licenses/LICENSE-2.0.html", } ) TYPE: Optional[Dict[str, Union[str, Any]]] DEFAULT: None openapi_prefix A URL prefix for the OpenAPI URL. TYPE: str DEFAULT: '' root_path A path prefix handled by a proxy that is not seen by the application but is seen by external clients, which affects things like Swagger UI. Read more about it at the FastAPI docs for Behind a Proxy. Example from fastapi import FastAPI app = FastAPI(root_path="/api/v1") TYPE: str DEFAULT: '' root_path_in_servers To disable automatically generating the URLs in the servers field in the autogenerated OpenAPI using the root_path. Read more about it in the FastAPI docs for Behind a Proxy. Example from fastapi import FastAPI app = FastAPI(root_path_in_servers=False) TYPE: bool DEFAULT: True responses Additional responses to be shown in OpenAPI. It will be added to the generated OpenAPI (e.g. visible at /docs). Read more about it in the FastAPI docs for Additional Responses in OpenAPI. And in the FastAPI docs for Bigger Applications. TYPE: Optional[Dict[Union[int, str], Dict[str, Any]]] DEFAULT: None callbacks OpenAPI callbacks that should apply to all path operations. It will be added to the generated OpenAPI (e.g. visible at /docs). Read more about it in the FastAPI docs for OpenAPI Callbacks. TYPE: Optional[List[BaseRoute]] DEFAULT: None webhooks Add OpenAPI webhooks. This is similar to callbacks but it doesn't depend on specific path operations. It will be added to the generated OpenAPI (e.g. visible at /docs). Note: This is available since OpenAPI 3.1.0, FastAPI 0.99.0. Read more about it in the FastAPI docs for OpenAPI Webhooks. TYPE: Optional[APIRouter] DEFAULT: None deprecated Mark all path operations as deprecated. You probably don't need it, but it's available. It will be added to the generated OpenAPI (e.g. visible at /docs). Read more about it in the FastAPI docs for Path Operation Configuration. TYPE: Optional[bool] DEFAULT: None include_in_schema To include (or not) all the path operations in the generated OpenAPI. You probably don't need it, but it's available. This affects the generated OpenAPI (e.g. visible at /docs). Read more about it in the FastAPI docs for Query Parameters and String Validations. TYPE: bool DEFAULT: True swagger_ui_parameters Parameters to configure Swagger UI, the autogenerated interactive API documentation (by default at /docs). Read more about it in the FastAPI docs about how to Configure Swagger UI. TYPE: Optional[Dict[str, Any]] DEFAULT: None generate_unique_id_function Customize the function used to generate unique IDs for the path operations shown in the generated OpenAPI. This is particularly useful when automatically generating clients or SDKs for your API. Read more about it in the FastAPI docs about how to Generate Clients. TYPE: Callable[[APIRoute], str] DEFAULT: Default(generate_unique_id) separate_input_output_schemas Whether to generate separate OpenAPI schemas for request body and response body when the results would be more precise. This is particularly useful when automatically generating clients. For example, if you have a model like: from pydantic import BaseModel class Item(BaseModel): name: str tags: list[str] = [] When Item is used for input, a request body, tags is not required, the client doesn't have to provide it. But when using Item for output, for a response body, tags is always available because it has a default value, even if it's just an empty list. So, the client should be able to always expect it. In this case, there would be two different schemas, one for input and another one for output. TYPE: bool DEFAULT: True openapi_external_docs This field allows you to provide additional external documentation links. If provided, it must be a dictionary containing: description: A brief description of the external documentation. url: The URL pointing to the external documentation. The value MUST be a valid URL format. Example: from fastapi import FastAPI external_docs = { "description": "Detailed API Reference", "url": "https://example.com/api-docs", } app = FastAPI(openapi_external_docs=external_docs) TYPE: Optional[Dict[str, Any]] DEFAULT: None extra Extra keyword arguments to be stored in the app, not used by FastAPI anywhere. TYPE: Any DEFAULT: {} Source code in fastapi/applications.py 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 927 928 929 930 931 932 933 934 935 936 937 938 939 940 941 942 943 944 945 946 947 948 949 950 951 952 953 954 955 956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976 977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000def __init__( self: AppType, , debug: Annotated[ bool, Doc( """ Boolean indicating if debug tracebacks should be returned on server errors. Read more in the [Starlette docs for Applications](https://www.starlette.dev/applications/#instantiating-the-application). """ ), ] = False, routes: Annotated[ Optional[List[BaseRoute]], Doc( """ Note: you probably shouldn't use this parameter, it is inherited from Starlette and supported for compatibility. --- A list of routes to serve incoming HTTP and WebSocket requests. """ ), deprecated( """ You normally wouldn't use this parameter with FastAPI, it is inherited from Starlette and supported for compatibility. In FastAPI, you normally would use the path operation methods, like app.get(), app.post(), etc. """ ), ] = None, title: Annotated[ str, Doc( """ The title of the API. It will be added to the generated OpenAPI (e.g. visible at /docs). Read more in the [FastAPI docs for Metadata and Docs URLs](https://fastapi.tiangolo.com/tutorial/metadata/#metadata-for-api). Example ``python from fastapi import FastAPI app = FastAPI(title="ChimichangApp") ` """ ), ] = "FastAPI", summary: Annotated[ Optional[str], Doc( """ A short summary of the API. It will be added to the generated OpenAPI (e.g. visible at /docs). Read more in the [FastAPI docs for Metadata and Docs URLs](https://fastapi.tiangolo.com/tutorial/metadata/#metadata-for-api). Example `python from fastapi import FastAPI app = FastAPI(summary="Deadpond's favorite app. Nuff said.") ` """ ), ] = None, description: Annotated[ str, Doc( ''' A description of the API. Supports Markdown (using [CommonMark syntax](https://commonmark.org/)). It will be added to the generated OpenAPI (e.g. visible at /docs). Read more in the [FastAPI docs for Metadata and Docs URLs](https://fastapi.tiangolo.com/tutorial/metadata/#metadata-for-api). Example `python from fastapi import FastAPI app = FastAPI( description=""" ChimichangApp API helps you do awesome stuff. 🚀 ## Items You can read items. ## Users You will be able to: Create users (_not implemented_). Read users (_not implemented_). """ ) ` ''' ), ] = "", version: Annotated[ str, Doc( """ The version of the API. Note This is the version of your application, not the version of the OpenAPI specification nor the version of FastAPI being used. It will be added to the generated OpenAPI (e.g. visible at /docs). Read more in the [FastAPI docs for Metadata and Docs URLs](https://fastapi.tiangolo.com/tutorial/metadata/#metadata-for-api). Example `python from fastapi import FastAPI app = FastAPI(version="0.0.1") ` """ ), ] = "0.1.0", openapi_url: Annotated[ Optional[str], Doc( """ The URL where the OpenAPI schema will be served from. If you set it to None, no OpenAPI schema will be served publicly, and the default automatic endpoints /docs and /redoc will also be disabled. Read more in the [FastAPI docs for Metadata and Docs URLs](https://fastapi.tiangolo.com/tutorial/metadata/#openapi-url). Example `python from fastapi import FastAPI app = FastAPI(openapi_url="/api/v1/openapi.json") ` """ ), ] = "/openapi.json", openapi_tags: Annotated[ Optional[List[Dict[str, Any]]], Doc( """ A list of tags used by OpenAPI, these are the same tags you can set in the path operations, like: @app.get("/users/", tags=["users"]) @app.get("/items/", tags=["items"]) The order of the tags can be used to specify the order shown in tools like Swagger UI, used in the automatic path /docs. It's not required to specify all the tags used. The tags that are not declared MAY be organized randomly or based on the tools' logic. Each tag name in the list MUST be unique. The value of each item is a dict containing: name: The name of the tag. description: A short description of the tag. [CommonMark syntax](https://commonmark.org/) MAY be used for rich text representation. externalDocs: Additional external documentation for this tag. If provided, it would contain a dict with: description: A short description of the target documentation. [CommonMark syntax](https://commonmark.org/) MAY be used for rich text representation. url: The URL for the target documentation. Value MUST be in the form of a URL. Read more in the [FastAPI docs for Metadata and Docs URLs](https://fastapi.tiangolo.com/tutorial/metadata/#metadata-for-tags). Example `python from fastapi import FastAPI tags_metadata = [ { "name": "users", "description": "Operations with users. The login logic is also here.", }, { "name": "items", "description": "Manage items. So _fancy_ they have their own docs.", "externalDocs": { "description": "Items external docs", "url": "https://fastapi.tiangolo.com/", }, }, ] app = FastAPI(openapi_tags=tags_metadata) ` """ ), ] = None, servers: Annotated[ Optional[List[Dict[str, Union[str, Any]]]], Doc( """ A list of dicts with connectivity information to a target server. You would use it, for example, if your application is served from different domains and you want to use the same Swagger UI in the browser to interact with each of them (instead of having multiple browser tabs open). Or if you want to leave fixed the possible URLs. If the servers list is not provided, or is an empty list, the servers property in the generated OpenAPI will be: a dict with a url value of the application's mounting point (root_path) if it's different from /. otherwise, the servers property will be omitted from the OpenAPI schema. Each item in the list is a dict containing: url: A URL to the target host. This URL supports Server Variables and MAY be relative, to indicate that the host location is relative to the location where the OpenAPI document is being served. Variable substitutions will be made when a variable is named in {brackets}. description: An optional string describing the host designated by the URL. [CommonMark syntax](https://commonmark.org/) MAY be used for rich text representation. variables: A dict between a variable name and its value. The value is used for substitution in the server's URL template. Read more in the [FastAPI docs for Behind a Proxy](https://fastapi.tiangolo.com/advanced/behind-a-proxy/#additional-servers). Example `python from fastapi import FastAPI app = FastAPI( servers=[ {"url": "https://stag.example.com", "description": "Staging environment"}, {"url": "https://prod.example.com", "description": "Production environment"}, ] ) ` """ ), ] = None, dependencies: Annotated[ Optional[Sequence[Depends]], Doc( """ A list of global dependencies, they will be applied to each path operation, including in sub-routers. Read more about it in the [FastAPI docs for Global Dependencies](https://fastapi.tiangolo.com/tutorial/dependencies/global-dependencies/). Example `python from fastapi import Depends, FastAPI from .dependencies import func_dep_1, func_dep_2 app = FastAPI(dependencies=[Depends(func_dep_1), Depends(func_dep_2)]) ` """ ), ] = None, default_response_class: Annotated[ Type[Response], Doc( """ The default response class to be used. Read more in the [FastAPI docs for Custom Response - HTML, Stream, File, others](https://fastapi.tiangolo.com/advanced/custom-response/#default-response-class). Example `python from fastapi import FastAPI from fastapi.responses import ORJSONResponse app = FastAPI(default_response_class=ORJSONResponse) ` """ ), ] = Default(JSONResponse), redirect_slashes: Annotated[ bool, Doc( """ Whether to detect and redirect slashes in URLs when the client doesn't use the same format. Example `python from fastapi import FastAPI app = FastAPI(redirect_slashes=True) # the default @app.get("/items/") async def read_items(): return [{"item_id": "Foo"}] ` With this app, if a client goes to /items (without a trailing slash), they will be automatically redirected with an HTTP status code of 307 to /items/. """ ), ] = True, docs_url: Annotated[ Optional[str], Doc( """ The path to the automatic interactive API documentation. It is handled in the browser by Swagger UI. The default URL is /docs. You can disable it by setting it to None. If openapi_url is set to None, this will be automatically disabled. Read more in the [FastAPI docs for Metadata and Docs URLs](https://fastapi.tiangolo.com/tutorial/metadata/#docs-urls). Example `python from fastapi import FastAPI app = FastAPI(docs_url="/documentation", redoc_url=None) ` """ ), ] = "/docs", redoc_url: Annotated[ Optional[str], Doc( """ The path to the alternative automatic interactive API documentation provided by ReDoc. The default URL is /redoc. You can disable it by setting it to None. If openapi_url is set to None, this will be automatically disabled. Read more in the [FastAPI docs for Metadata and Docs URLs](https://fastapi.tiangolo.com/tutorial/metadata/#docs-urls). Example `python from fastapi import FastAPI app = FastAPI(docs_url="/documentation", redoc_url="redocumentation") ` """ ), ] = "/redoc", swagger_ui_oauth2_redirect_url: Annotated[ Optional[str], Doc( """ The OAuth2 redirect endpoint for the Swagger UI. By default it is /docs/oauth2-redirect. This is only used if you use OAuth2 (with the "Authorize" button) with Swagger UI. """ ), ] = "/docs/oauth2-redirect", swagger_ui_init_oauth: Annotated[ Optional[Dict[str, Any]], Doc( """ OAuth2 configuration for the Swagger UI, by default shown at /docs. Read more about the available configuration options in the [Swagger UI docs](https://swagger.io/docs/open-source-tools/swagger-ui/usage/oauth2/). """ ), ] = None, middleware: Annotated[ Optional[Sequence[Middleware]], Doc( """ List of middleware to be added when creating the application. In FastAPI you would normally do this with app.add_middleware() instead. Read more in the [FastAPI docs for Middleware](https://fastapi.tiangolo.com/tutorial/middleware/). """ ), ] = None, exception_handlers: Annotated[ Optional[ Dict[ Union[int, Type[Exception]], Callable[[Request, Any], Coroutine[Any, Any, Response]], ] ], Doc( """ A dictionary with handlers for exceptions. In FastAPI, you would normally use the decorator @app.exception_handler(). Read more in the [FastAPI docs for Handling Errors](https://fastapi.tiangolo.com/tutorial/handling-errors/). """ ), ] = None, on_startup: Annotated[ Optional[Sequence[Callable[[], Any]]], Doc( """ A list of startup event handler functions. You should instead use the lifespan handlers. Read more in the [FastAPI docs for lifespan](https://fastapi.tiangolo.com/advanced/events/). """ ), ] = None, on_shutdown: Annotated[ Optional[Sequence[Callable[[], Any]]], Doc( """ A list of shutdown event handler functions. You should instead use the lifespan handlers. Read more in the [FastAPI docs for lifespan](https://fastapi.tiangolo.com/advanced/events/). """ ), ] = None, lifespan: Annotated[ Optional[Lifespan[AppType]], Doc( """ A Lifespan context manager handler. This replaces startup and shutdown functions with a single context manager. Read more in the [FastAPI docs for lifespan](https://fastapi.tiangolo.com/advanced/events/). """ ), ] = None, terms_of_service: Annotated[ Optional[str], Doc( """ A URL to the Terms of Service for your API. It will be added to the generated OpenAPI (e.g. visible at /docs). Read more at the [FastAPI docs for Metadata and Docs URLs](https://fastapi.tiangolo.com/tutorial/metadata/#metadata-for-api). Example `python app = FastAPI(terms_of_service="http://example.com/terms/") ` """ ), ] = None, contact: Annotated[ Optional[Dict[str, Union[str, Any]]], Doc( """ A dictionary with the contact information for the exposed API. It can contain several fields. name: (str) The name of the contact person/organization. url: (str) A URL pointing to the contact information. MUST be in the format of a URL. email: (str) The email address of the contact person/organization. MUST be in the format of an email address. It will be added to the generated OpenAPI (e.g. visible at /docs). Read more at the [FastAPI docs for Metadata and Docs URLs](https://fastapi.tiangolo.com/tutorial/metadata/#metadata-for-api). Example `python app = FastAPI( contact={ "name": "Deadpoolio the Amazing", "url": "http://x-force.example.com/contact/", "email": "dp@x-force.example.com", } ) ` """ ), ] = None, license_info: Annotated[ Optional[Dict[str, Union[str, Any]]], Doc( """ A dictionary with the license information for the exposed API. It can contain several fields. name: (str) REQUIRED (if a license_info is set). The license name used for the API. identifier: (str) An [SPDX](https://spdx.dev/) license expression for the API. The identifier field is mutually exclusive of the url field. Available since OpenAPI 3.1.0, FastAPI 0.99.0. url: (str) A URL to the license used for the API. This MUST be the format of a URL. It will be added to the generated OpenAPI (e.g. visible at /docs). Read more at the [FastAPI docs for Metadata and Docs URLs](https://fastapi.tiangolo.com/tutorial/metadata/#metadata-for-api). Example `python app = FastAPI( license_info={ "name": "Apache 2.0", "url": "https://www.apache.org/licenses/LICENSE-2.0.html", } ) ` """ ), ] = None, openapi_prefix: Annotated[ str, Doc( """ A URL prefix for the OpenAPI URL. """ ), deprecated( """ "openapi_prefix" has been deprecated in favor of "root_path", which follows more closely the ASGI standard, is simpler, and more automatic. """ ), ] = "", root_path: Annotated[ str, Doc( """ A path prefix handled by a proxy that is not seen by the application but is seen by external clients, which affects things like Swagger UI. Read more about it at the [FastAPI docs for Behind a Proxy](https://fastapi.tiangolo.com/advanced/behind-a-proxy/). Example `python from fastapi import FastAPI app = FastAPI(root_path="/api/v1") ` """ ), ] = "", root_path_in_servers: Annotated[ bool, Doc( """ To disable automatically generating the URLs in the servers field in the autogenerated OpenAPI using the root_path. Read more about it in the [FastAPI docs for Behind a Proxy](https://fastapi.tiangolo.com/advanced/behind-a-proxy/#disable-automatic-server-from-root_path). Example `python from fastapi import FastAPI app = FastAPI(root_path_in_servers=False) ` """ ), ] = True, responses: Annotated[ Optional[Dict[Union[int, str], Dict[str, Any]]], Doc( """ Additional responses to be shown in OpenAPI. It will be added to the generated OpenAPI (e.g. visible at /docs). Read more about it in the [FastAPI docs for Additional Responses in OpenAPI](https://fastapi.tiangolo.com/advanced/additional-responses/). And in the [FastAPI docs for Bigger Applications](https://fastapi.tiangolo.com/tutorial/bigger-applications/#include-an-apirouter-with-a-custom-prefix-tags-responses-and-dependencies). """ ), ] = None, callbacks: Annotated[ Optional[List[BaseRoute]], Doc( """ OpenAPI callbacks that should apply to all path operations. It will be added to the generated OpenAPI (e.g. visible at /docs). Read more about it in the [FastAPI docs for OpenAPI Callbacks](https://fastapi.tiangolo.com/advanced/openapi-callbacks/). """ ), ] = None, webhooks: Annotated[ Optional[routing.APIRouter], Doc( """ Add OpenAPI webhooks. This is similar to callbacks but it doesn't depend on specific path operations. It will be added to the generated OpenAPI (e.g. visible at /docs). Note: This is available since OpenAPI 3.1.0, FastAPI 0.99.0. Read more about it in the [FastAPI docs for OpenAPI Webhooks](https://fastapi.tiangolo.com/advanced/openapi-webhooks/). """ ), ] = None, deprecated: Annotated[ Optional[bool], Doc( """ Mark all path operations as deprecated. You probably don't need it, but it's available. It will be added to the generated OpenAPI (e.g. visible at /docs). Read more about it in the [FastAPI docs for Path Operation Configuration](https://fastapi.tiangolo.com/tutorial/path-operation-configuration/). """ ), ] = None, include_in_schema: Annotated[ bool, Doc( """ To include (or not) all the path operations in the generated OpenAPI. You probably don't need it, but it's available. This affects the generated OpenAPI (e.g. visible at /docs). Read more about it in the [FastAPI docs for Query Parameters and String Validations](https://fastapi.tiangolo.com/tutorial/query-params-str-validations/#exclude-parameters-from-openapi). """ ), ] = True, swagger_ui_parameters: Annotated[ Optional[Dict[str, Any]], Doc( """ Parameters to configure Swagger UI, the autogenerated interactive API documentation (by default at /docs). Read more about it in the [FastAPI docs about how to Configure Swagger UI](https://fastapi.tiangolo.com/how-to/configure-swagger-ui/). """ ), ] = None, generate_unique_id_function: Annotated[ Callable[[routing.APIRoute], str], Doc( """ Customize the function used to generate unique IDs for the path operations shown in the generated OpenAPI. This is particularly useful when automatically generating clients or SDKs for your API. Read more about it in the [FastAPI docs about how to Generate Clients](https://fastapi.tiangolo.com/advanced/generate-clients/#custom-generate-unique-id-function). """ ), ] = Default(generate_unique_id), separate_input_output_schemas: Annotated[ bool, Doc( """ Whether to generate separate OpenAPI schemas for request body and response body when the results would be more precise. This is particularly useful when automatically generating clients. For example, if you have a model like: `python from pydantic import BaseModel class Item(BaseModel): name: str tags: list[str] = [] ` When Item is used for input, a request body, tags is not required, the client doesn't have to provide it. But when using Item for output, for a response body, tags is always available because it has a default value, even if it's just an empty list. So, the client should be able to always expect it. In this case, there would be two different schemas, one for input and another one for output. """ ), ] = True, openapi_external_docs: Annotated[ Optional[Dict[str, Any]], Doc( """ This field allows you to provide additional external documentation links. If provided, it must be a dictionary containing: description: A brief description of the external documentation. url: The URL pointing to the external documentation. The value MUST be a valid URL format. Example: `python from fastapi import FastAPI external_docs = { "description": "Detailed API Reference", "url": "https://example.com/api-docs", } app = FastAPI(openapi_external_docs=external_docs) ` """ ), ] = None, extra: Annotated[ Any, Doc( """ Extra keyword arguments to be stored in the app, not used by FastAPI anywhere. """ ), ], ) -> None: self.debug = debug self.title = title self.summary = summary self.description = description self.version = version self.terms_of_service = terms_of_service self.contact = contact self.license_info = license_info self.openapi_url = openapi_url self.openapi_tags = openapi_tags self.root_path_in_servers = root_path_in_servers self.docs_url = docs_url self.redoc_url = redoc_url self.swagger_ui_oauth2_redirect_url = swagger_ui_oauth2_redirect_url self.swagger_ui_init_oauth = swagger_ui_init_oauth self.swagger_ui_parameters = swagger_ui_parameters self.servers = servers or [] self.separate_input_output_schemas = separate_input_output_schemas self.openapi_external_docs = openapi_external_docs self.extra = extra self.openapi_version: Annotated[ str, Doc( """ The version string of OpenAPI. FastAPI will generate OpenAPI version 3.1.0, and will output that as the OpenAPI version. But some tools, even though they might be compatible with OpenAPI 3.1.0, might not recognize it as a valid. So you could override this value to trick those tools into using the generated OpenAPI. Have in mind that this is a hack. But if you avoid using features added in OpenAPI 3.1.0, it might work for your use case. This is not passed as a parameter to the FastAPI class to avoid giving the false idea that FastAPI would generate a different OpenAPI schema. It is only available as an attribute. Example* `python from fastapi import FastAPI app = FastAPI() app.openapi_version = "3.0.2" ` """ ), ] = "3.1.0" self.openapi_schema: Optional[Dict[str, Any]] = None if self.openapi_url: assert self.title, "A title must be provided for OpenAPI, e.g.: 'My API'" assert self.version, "A version must be provided for OpenAPI, e.g.: '2.1.0'" # TODO: remove when discarding the openapi_prefix parameter if openapi_prefix: logger.warning( '"openapi_prefix" has been deprecated in favor of "root_path", which ' "follows more closely the ASGI standard, is simpler, and more " "automatic. Check the docs at " "https://fastapi.tiangolo.com/advanced/sub-applications/" ) self.webhooks: Annotated[ routing.APIRouter, Doc( """ The app.webhooks attribute is an APIRouter with the path operations that will be used just for documentation of webhooks. Read more about it in the [FastAPI docs for OpenAPI Webhooks](https://fastapi.tiangolo.com/advanced/openapi-webhooks/). """ ), ] = webhooks or routing.APIRouter() self.root_path = root_path or openapi_prefix self.state: Annotated[ State, Doc( """ A state object for the application. This is the same object for the entire application, it doesn't change from request to request. You normally wouldn't use this in FastAPI, for most of the cases you would instead use FastAPI dependencies. This is simply inherited from Starlette. Read more about it in the [Starlette docs for Applications](https://www.starlette.dev/applications/#storing-state-on-the-app-instance). """ ), ] = State() self.dependency_overrides: Annotated[ Dict[Callable[..., Any], Callable[..., Any]], Doc( """ A dictionary with overrides for the dependencies. Each key is the original dependency callable, and the value is the actual dependency that should be called. This is for testing, to replace expensive dependencies with testing versions. Read more about it in the [FastAPI docs for Testing Dependencies with Overrides](https://fastapi.tiangolo.com/advanced/testing-dependencies/). """ ), ] = {} self.router: routing.APIRouter = routing.APIRouter( routes=routes, redirect_slashes=redirect_slashes, dependency_overrides_provider=self, on_startup=on_startup, on_shutdown=on_shutdown, lifespan=lifespan, default_response_class=default_response_class, dependencies=dependencies, callbacks=callbacks, deprecated=deprecated, include_in_schema=include_in_schema, responses=responses, generate_unique_id_function=generate_unique_id_function, ) self.exception_handlers: Dict[ Any, Callable[[Request, Any], Union[Response, Awaitable[Response]]] ] = {} if exception_handlers is None else dict(exception_handlers) self.exception_handlers.setdefault(HTTPException, http_exception_handler) self.exception_handlers.setdefault( RequestValidationError, request_validation_exception_handler ) self.exception_handlers.setdefault( WebSocketRequestValidationError, # Starlette still has incorrect type specification for the handlers websocket_request_validation_exception_handler, # type: ignore ) self.user_middleware: List[Middleware] = ( [] if middleware is None else list(middleware) ) self.middleware_stack: Union[ASGIApp, None] = None self.setup() openapi_version instance-attribute ¶ openapi_version = '3.1.0' The version string of OpenAPI. FastAPI will generate OpenAPI version 3.1.0, and will output that as the OpenAPI version. But some tools, even though they might be compatible with OpenAPI 3.1.0, might not recognize it as a valid. So you could override this value to trick those tools into using the generated OpenAPI. Have in mind that this is a hack. But if you avoid using features added in OpenAPI 3.1.0, it might work for your use case. This is not passed as a parameter to the FastAPI class to avoid giving the false idea that FastAPI would generate a different OpenAPI schema. It is only available as an attribute. Example from fastapi import FastAPI app = FastAPI() app.openapi_version = "3.0.2" webhooks instance-attribute ¶ webhooks = webhooks or APIRouter() The app.webhooks attribute is an APIRouter with the path operations that will be used just for documentation of webhooks. Read more about it in the FastAPI docs for OpenAPI Webhooks. state instance-attribute ¶ state = State() A state object for the application. This is the same object for the entire application, it doesn't change from request to request. You normally wouldn't use this in FastAPI, for most of the cases you would instead use FastAPI dependencies. This is simply inherited from Starlette. Read more about it in the Starlette docs for Applications. dependency_overrides instance-attribute ¶ dependency_overrides = {} A dictionary with overrides for the dependencies. Each key is the original dependency callable, and the value is the actual dependency that should be called. This is for testing, to replace expensive dependencies with testing versions. Read more about it in the FastAPI docs for Testing Dependencies with Overrides. openapi ¶ openapi() Generate the OpenAPI schema of the application. This is called by FastAPI internally. The first time it is called it stores the result in the attribute app.openapi_schema, and next times it is called, it just returns that same result. To avoid the cost of generating the schema every time. If you need to modify the generated OpenAPI schema, you could modify it. Read more in the FastAPI docs for OpenAPI. Source code in fastapi/applications.py 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081def openapi(self) -> Dict[str, Any]: """ Generate the OpenAPI schema of the application. This is called by FastAPI internally. The first time it is called it stores the result in the attribute app.openapi_schema, and next times it is called, it just returns that same result. To avoid the cost of generating the schema every time. If you need to modify the generated OpenAPI schema, you could modify it. Read more in the [FastAPI docs for OpenAPI](https://fastapi.tiangolo.com/how-to/extending-openapi/). """ if not self.openapi_schema: self.openapi_schema = get_openapi( title=self.title, version=self.version, openapi_version=self.openapi_version, summary=self.summary, description=self.description, terms_of_service=self.terms_of_service, contact=self.contact, license_info=self.license_info, routes=self.routes, webhooks=self.webhooks.routes, tags=self.openapi_tags, servers=self.servers, separate_input_output_schemas=self.separate_input_output_schemas, external_docs=self.openapi_external_docs, ) return self.openapi_schema websocket ¶ websocket(path, name=None, , dependencies=None) Decorate a WebSocket function. Read more about it in the FastAPI docs for WebSockets. Example from fastapi import FastAPI, WebSocket app = FastAPI() @app.websocket("/ws") async def websocket_endpoint(websocket: WebSocket): await websocket.accept() while True: data = await websocket.receive_text() await websocket.send_text(f"Message text was: {data}") PARAMETER DESCRIPTION path WebSocket path. TYPE: str name A name for the WebSocket. Only used internally. TYPE: Optional[str] DEFAULT: None dependencies A list of dependencies (using Depends()) to be used for this WebSocket. Read more about it in the FastAPI docs for WebSockets. TYPE: Optional[Sequence[Depends]] DEFAULT: None Source code in fastapi/applications.py 1275 1276 1277 1278 1279 1280 1281 1282 1283 1284 1285 1286 1287 1288 1289 1290 1291 1292 1293 1294 1295 1296 1297 1298 1299 1300 1301 1302 1303 1304 1305 1306 1307 1308 1309 1310 1311 1312 1313 1314 1315 1316 1317 1318 1319 1320 1321 1322 1323 1324 1325 1326 1327 1328 1329 1330 1331 1332 1333 1334 1335 1336 1337 1338def websocket( self, path: Annotated[ str, Doc( """ WebSocket path. """ ), ], name: Annotated[ Optional[str], Doc( """ A name for the WebSocket. Only used internally. """ ), ] = None, , dependencies: Annotated[ Optional[Sequence[Depends]], Doc( """ A list of dependencies (using Depends()) to be used for this WebSocket. Read more about it in the [FastAPI docs for WebSockets](https://fastapi.tiangolo.com/advanced/websockets/). """ ), ] = None, ) -> Callable[[DecoratedCallable], DecoratedCallable]: """ Decorate a WebSocket function. Read more about it in the [FastAPI docs for WebSockets](https://fastapi.tiangolo.com/advanced/websockets/). Example `python from fastapi import FastAPI, WebSocket app = FastAPI() @app.websocket("/ws") async def websocket_endpoint(websocket: WebSocket): await websocket.accept() while True: data = await websocket.receive_text() await websocket.send_text(f"Message text was: {data}") `` """ def decorator(func: DecoratedCallable) -> DecoratedCallable: self.add_api_websocket_route( path, func, name=name, dependencies=dependencies, ) return func return decorator include_router ¶ include_router( router, , prefix="", tags=None, dependencies=None, responses=None, deprecated=None, include_in_schema=True, default_response_class=Default(JSONResponse), callbacks=None, generate_unique_id_function=Default(generate_unique_id) ) Include an APIRouter in the same app. Read more about it in the FastAPI docs for Bigger Applications. Example¶ from fastapi import FastAPI from .users import us