App Basics

New Applications

Every view project will have a new_app call. The simplest app looks like this:

from view import new_app

app = new_app()

new_app does a few important things:

• Loads the configuration, regardless of whether a config file exists.
• Sets the App address for use by get_app (more on that later).
• Loads finalization code for when the app closes.

While it's not required for every app, naming your app variable app is the proper convention for view, as that's the default variable searched for when using the view serve command, but more on that in a moment.

For now, just try to stick with naming your app file app.py and your view.App instance app.

view.app.App

Bases: ViewApp

Public view.py app object.

Source code in src/view/app.py

class App(ViewApp):
    """Public view.py app object."""

    def __init__(self, config: Config) -> None:
        """
        Args:
            config: Configuration object to be used. Automatically generated by `new_app`.
        """
        supply_parsers(self)
        self.config = config
        self._set_dev_state(config.dev)
        self._manual_routes: list[Route] = []
        self.routes: list[Route] = []
        self.loaded: bool = False
        self.running = False
        self._docs: DocsType = {}
        self.loaded_routes: list[Route] = []
        self.templaters: dict[str, Any] = {}

        Service.log.setLevel(
            config.log.level
            if not isinstance(config.log.level, str)
            else config.log.level.upper()
        )

        if config.dev:
            if os.environ.get("VIEW_PROD") is not None:
                Service.warning("VIEW_PROD is set but dev is set to true")

            format_warnings()
            weakref.finalize(self, self._finalize)

            if config.log.pretty_tracebacks:
                install(show_locals=True)

            rich_handler = sys.excepthook

            def _hook(tp: type[B], value: B, traceback: Traceback) -> None:
                rich_handler(tp, value, traceback)
                os.environ["_VIEW_CANCEL_FINALIZERS"] = "1"

                if isinstance(value, ViewError):
                    if value.hint:
                        print(value.hint)

            sys.excepthook = _hook
            with suppress(UnsupportedOperation):
                faulthandler.enable()
        else:
            os.environ["VIEW_PROD"] = "1"

        if config.log.level == "debug":
            enable_debug()

        self.running = False

    def _finalize(self) -> None:
        if os.environ.get("_VIEW_CANCEL_FINALIZERS"):
            return

        if self.loaded:
            return

        warnings.warn("load() was never called (did you forget to start the app?)")
        split = self.config.app.app_path.split(":", maxsplit=1)

        if len(split) != 2:
            return

        app_name = split[1]

        print(
            make_hint(
                "Add this to your code",
                split[0],
                line=-1,
                prepend=f"\n{app_name}.run()",
            )
        )

    def _push_route(self, route: Route) -> None:
        if route in self._manual_routes:
            return

        self._manual_routes.append(route)

    def route(
        self,
        path_or_route: str | None | RouteOrCallable = None,
        doc: str | None = None,
        *,
        cache_rate: int = -1,
        methods: Iterable[StrMethod] | None = None
    ) -> Callable[[RouteOrCallable], Route]:
        """Add a route that can be called with any method (or only specific methods).

        Args:
            path_or_route: The path to this route, or the route itself.
            doc: The description of the route to be used in documentation.
            cache_rate: Reload the cache for this route every x number of requests. `-1` means to never cache.
            methods: Methods that can be used to access this route. If this is `None`, then all methods are allowed.

        Example:
            ```py
            from view import route

            @route("/", methods=("GET", "POST"))
            async def index():
                return "Hello, view.py!"
            ```
        """
        def inner(r: RouteOrCallable) -> Route:
            new_r = route_impl(path_or_route, doc, cache_rate=cache_rate, methods=methods)(r)
            self._push_route(new_r)
            return new_r

        return inner

    def _method_wrapper(
        self,
        path: str,
        doc: str | None,
        cache_rate: int,
        target: Callable[..., Any],
        # i dont really feel like typing this properly
    ) -> Callable[[RouteOrCallable], Route]:
        def inner(route: RouteOrCallable) -> Route:
            new_route = target(path, doc, cache_rate=cache_rate)(route)
            self._push_route(new_route)
            return new_route

        return inner

    def get(self, path: str, doc: str | None = None, *, cache_rate: int = -1):
        """Add a GET route.

        Args:
            path_or_route: The path to this route, or the route itself.
            doc: The description of the route to be used in documentation.
            cache_rate: Reload the cache for this route every x number of requests. `-1` means to never cache.

        Example:
            ```py
            from view import new_app

            app = new_app()

            @app.get("/")
            async def index():
                return "Hello, view.py!"

            app.run()
            ```
        """
        return self._method_wrapper(path, doc, cache_rate, get)

    def post(self, path: str, doc: str | None = None, *, cache_rate: int = -1):
        """Add a POST route.

        Args:
            path_or_route: The path to this route, or the route itself.
            doc: The description of the route to be used in documentation.
            cache_rate: Reload the cache for this route every x number of requests. `-1` means to never cache.

        Example:
            ```py
            from view import new_app

            app = new_app()

            @app.post("/")
            async def index():
                return "Hello, view.py!"

            app.run()
            ```
        """
        return self._method_wrapper(path, doc, cache_rate, post)

    def delete(self, path: str, doc: str | None = None, *, cache_rate: int = -1):
        """Add a DELETE route.

        Args:
            path_or_route: The path to this route, or the route itself.
            doc: The description of the route to be used in documentation.
            cache_rate: Reload the cache for this route every x number of requests. `-1` means to never cache.

        Example:
            ```py
            from view import new_app

            app = new_app()

            @app.delete("/")
            async def index():
                return "Hello, view.py!"

            app.run()
            ```
        """
        return self._method_wrapper(path, doc, cache_rate, delete)

    def patch(
        self,
        path: str,
        doc: str | None = None,
        *,
        cache_rate: int = -1,
    ):
        """Add a PATCH route.

        Args:
            path_or_route: The path to this route, or the route itself.
            doc: The description of the route to be used in documentation.
            cache_rate: Reload the cache for this route every x number of requests. `-1` means to never cache.

        Example:
            ```py
            from view import new_app

            app = new_app()

            @app.patch("/")
            async def index():
                return "Hello, view.py!"

            app.run()
            ```
        """
        return self._method_wrapper(path, doc, cache_rate, patch)

    def put(self, path: str, doc: str | None = None, *, cache_rate: int = -1):
        """Add a PUT route.

        Args:
            path_or_route: The path to this route, or the route itself.
            doc: The description of the route to be used in documentation.
            cache_rate: Reload the cache for this route every x number of requests. `-1` means to never cache.

        Example:
            ```py
            from view import new_app

            app = new_app()

            @app.put("/")
            async def index():
                return "Hello, view.py!"

            app.run()
            ```
        """
        return self._method_wrapper(path, doc, cache_rate, put)

    def options(self, path: str, doc: str | None = None, *, cache_rate: int = -1):
        """Add an OPTIONS route.

        Args:
            path_or_route: The path to this route, or the route itself.
            doc: The description of the route to be used in documentation.
            cache_rate: Reload the cache for this route every x number of requests. `-1` means to never cache.

        Example:
            ```py
            from view import new_app

            app = new_app()

            @app.options("/")
            async def index():
                return "Hello, view.py!"

            app.run()
            ```
        """
        return self._method_wrapper(path, doc, cache_rate, options)

    def _set_log_arg(self, kwargs: _LogArgs, key: str) -> None:
        if key not in kwargs:
            kwargs[key] = getattr(self.config.log.user, key)

    def _splat_log_args(self, kwargs: _LogArgs) -> _LogArgs:
        self._set_log_arg(kwargs, "log_file")
        self._set_log_arg(kwargs, "show_time")
        self._set_log_arg(kwargs, "show_caller")
        self._set_log_arg(kwargs, "show_color")
        self._set_log_arg(kwargs, "show_urgency")
        self._set_log_arg(kwargs, "file_write")
        self._set_log_arg(kwargs, "strftime")

        if "caller_frame" not in kwargs:
            frame = inspect.currentframe()
            assert frame, "failed to get frame"
            back = frame.f_back
            assert back, "frame has no f_back"
            kwargs["caller_frame"] = back

        return kwargs

    def debug(self, *messages: object, **kwargs: Unpack[_LogArgs]) -> None:
        log(*messages, urgency="debug", **self._splat_log_args(kwargs))

    def info(self, *messages: object, **kwargs: Unpack[_LogArgs]) -> None:
        log(*messages, urgency="info", **self._splat_log_args(kwargs))

    def warning(self, *messages: object, **kwargs: Unpack[_LogArgs]) -> None:
        log(*messages, urgency="warning", **self._splat_log_args(kwargs))

    def error(self, *messages: object, **kwargs: Unpack[_LogArgs]) -> None:
        log(*messages, urgency="error", **self._splat_log_args(kwargs))

    def critical(self, *messages: object, **kwargs: Unpack[_LogArgs]) -> None:
        log(*messages, urgency="critical", **self._splat_log_args(kwargs))

    def query(
        self,
        name: str,
        *tps: type[V],
        doc: str | None = None,
        default: V | None | _NoDefaultType = _NoDefault,
    ):
        """Set a query parameter.

        Args:
            name: Name of the parameter.
            tps: Types that can be passed to the server. If empty, any is used.
            doc: Description of this query parameter.
            default: Default value to be used if not supplied.
        """

        def inner(func: RouteOrCallable) -> Route:
            route = query_impl(name, *tps, doc=doc, default=default)(func)
            self._push_route(route)
            return route

        return inner

    def body(
        self,
        name: str,
        *tps: type[V],
        doc: str | None = None,
        default: V | None | _NoDefaultType = _NoDefault,
    ):
        """Set a body parameter.

        Args:
            name: Name of the parameter.
            tps: Types that can be passed to the server. If empty, any is used.
            doc: Description of this body parameter.
            default: Default value to be used if not supplied.
        """

        def inner(func: RouteOrCallable) -> Route:
            route = body_impl(name, *tps, doc=doc, default=default)(func)
            self._push_route(route)
            return route

        return inner

    async def template(
        self,
        name: str | Path,
        directory: str | Path | None = _ConfigSpecified,
        engine: TemplateEngine | None = _ConfigSpecified,
        frame: Frame | None | _CurrentFrameType = _CurrentFrame,
        **parameters: Any,
    ) -> HTML:
        """Render a template with the specified engine. This returns a view.py HTML response."""
        return await template(name, directory, engine, frame, app=self, **parameters)

    def context(self, r_or_none: RouteOrCallable | None = None):
        return context_impl(r_or_none)

    async def _app(self, scope, receive, send) -> None:
        return await self.asgi_app_entry(scope, receive, send)

    def load(self, routes: list[Route] | None = None) -> None:
        """Load the app. This is automatically called most of the time and should only be called manually during manual loading.

        Args:
            routes: Routes to load into the app.
        """
        if self.loaded:
            if routes:
                finalize(routes, self)
            Internal.warning("load called twice")
            return

        if routes and (self.config.app.loader != "manual"):
            warnings.warn(_ROUTES_WARN_MSG)

        if self.config.app.loader == "filesystem":
            load_fs(self, self.config.app.loader_path)
        elif self.config.app.loader == "simple":
            load_simple(self, self.config.app.loader_path)
        elif self.config.app.loader == "patterns":
            load_patterns(self, self.config.app.loader_path)
        else:
            finalize([*(routes or ()), *self._manual_routes], self)

        self.loaded = True

        from .routing import RouteInput

        for r in self.loaded_routes:
            if not r.path:
                continue

            body = {}
            query = {}

            for i in r.inputs:
                if not isinstance(i, RouteInput):
                    continue

                target = body if i.is_body else query
                target[i.name] = InputDoc(
                    i.doc or "No description provided.", i.tp, i.default
                )

            if r.method:
                self._docs[(r.method.name, r.path)] = RouteDoc(
                    r.doc or "No description provided.", body, query
                )
            else:
                self._docs[
                    (tuple([i.name for i in r.method_list]) if r.method_list else (
                        "GET",
                        "POST",
                        "PUT",
                        "PATCH",
                        "DELETE",
                        "OPTIONS",
                    ), r.path)] = RouteDoc(
                    r.doc or "No description provided.", body, query
                )

    async def _spawn(self, coro: Coroutine[Any, Any, Any]):
        Internal.info(f"using event loop: {asyncio.get_event_loop()}")
        Internal.info(f"spawning {coro}")

        task = asyncio.create_task(coro)
        if self.config.log.hijack:
            if self.config.server.backend == "uvicorn":
                Internal.info("hijacking uvicorn")
                for log in (
                    logging.getLogger("uvicorn.error"),
                    logging.getLogger("uvicorn.access"),
                ):
                    log.addFilter(UvicornHijack())
            else:
                Internal.info("hijacking hypercorn")

        if self.config.log.fancy:
            if not self.config.log.hijack:
                raise ConfigurationError("hijack must be enabled for fancy mode")

            enter_server()

        self.running = True
        Internal.debug("here we go!")
        await task
        self.running = False

        if self.config.log.fancy:
            exit_server()

        Internal.info("server closed")

    def _run(self, start_target: Callable[..., Any] | None = None) -> Any:
        self.load()
        Internal.info("starting server!")
        server = self.config.server.backend
        uvloop_enabled = False

        if self.config.app.uvloop is True:
            uvloop = importlib.import_module("uvloop")
            uvloop.install()
            uvloop_enabled = True
        elif self.config.app.uvloop == "decide":
            with suppress(ModuleNotFoundError):
                uvloop = importlib.import_module("uvloop")
                uvloop.install()
                uvloop_enabled = True

        start = start_target or asyncio.run

        if server == "uvicorn":
            config = uvicorn.Config(
                self._app,
                port=self.config.server.port,
                host=str(self.config.server.host),
                log_level="debug" if self.config.dev else "info",
                lifespan="on",
                factory=False,
                interface="asgi3",
                loop="uvloop" if uvloop_enabled else "asyncio",
                **self.config.server.extra_args,
            )
            server = uvicorn.Server(config)

            return start(self._spawn(server.serve()))

        elif server == "hypercorn":
            raise NotImplementedError
            conf = hypercorn.Config()
            conf.loglevel = "debug" if self.config.dev else "info"
            conf.bind = [
                f"{self.config.server.host}:{self.config.server.port}",
            ]

            for k, v in self.config.server.extra_args.items():
                setattr(conf, k, v)

            return start(
                importlib.import_module("hypercorn.asyncio").serve(self._app, conf)
            )
        else:
            raise NotImplementedError("viewserver is not implemented yet")

    def run(self, *, fancy: bool | None = None) -> None:
        """Run the app."""
        if fancy is not None:
            self.config.log.fancy = fancy

        frame = inspect.currentframe()
        assert frame, "failed to get frame"
        assert frame.f_back, "frame has no f_back"

        back = frame.f_back
        base = os.path.basename(back.f_code.co_filename)
        app_path = self.config.app.app_path
        fname = app_path.split(":")[0]
        if base != fname:
            warnings.warn(
                f"ran app from {base}, but app path is {fname} in config",
            )

        if (not os.environ.get("_VIEW_RUN")) and (
            back.f_globals.get("__name__") == "__main__"
        ):
            self._run()
        else:
            Internal.info("called run, but env or scope prevented startup")

    def run_threaded(self, *, daemon: bool = True) -> Thread:
        """Run the app in a thread."""
        thread = Thread(target=self._run, daemon=daemon)
        thread.start()
        return thread

    def run_async(
        self,
        loop: asyncio.AbstractEventLoop | None = None,
    ) -> None:
        """Run the app in an event loop."""
        self._run((loop or asyncio.get_event_loop()).run_until_complete)

    def run_task(
        self,
        loop: asyncio.AbstractEventLoop | None = None,
    ) -> asyncio.Task[None]:
        """Run the app as a task."""
        return self._run((loop or asyncio.get_event_loop()).create_task)

    start = run

    def __repr__(self) -> str:
        return f"App(config={self.config!r})"

    @asynccontextmanager
    async def test(self):
        """Open the testing context."""
        self.load()
        ctx = TestingContext(self.asgi_app_entry)
        try:
            yield ctx
        finally:
            await ctx.stop()

    @overload
    def docs(self, file: None = None) -> str:
        ...

    @overload
    def docs(self, file: TextIO) -> None:
        ...

    @overload
    def docs(
        self,
        file: Path,
        *,
        encoding: str = "utf-8",
        overwrite: bool = True,
    ) -> None:
        ...

    @overload
    def docs(
        self,
        file: str,
        *,
        encoding: str = "utf-8",
        overwrite: bool = True,
    ) -> None:
        ...

    def docs(
        self,
        file: str | TextIO | Path | None = None,
        *,
        encoding: str = "utf-8",
        overwrite: bool = True,
    ) -> str | None:
        """Generate documentation for the app."""
        self.load()
        md = markdown_docs(self._docs)

        if not file:
            return md

        if isinstance(file, str):
            if not overwrite:
                Path(file).write_text(md, encoding=encoding)
            else:
                with open(file, "w", encoding=encoding) as f:
                    f.write(md)
        elif isinstance(file, Path):
            if overwrite:
                with open(file, "w", encoding=encoding) as f:
                    f.write(md)
            else:
                file.write_text(md)
        else:
            file.write(md)

view.app.App.__init__(config: Config) -> None

Parameters:

Name	Type	Description	Default
config	Config	Configuration object to be used. Automatically generated by new_app.	required

Source code in src/view/app.py

def __init__(self, config: Config) -> None:
    """
    Args:
        config: Configuration object to be used. Automatically generated by `new_app`.
    """
    supply_parsers(self)
    self.config = config
    self._set_dev_state(config.dev)
    self._manual_routes: list[Route] = []
    self.routes: list[Route] = []
    self.loaded: bool = False
    self.running = False
    self._docs: DocsType = {}
    self.loaded_routes: list[Route] = []
    self.templaters: dict[str, Any] = {}

    Service.log.setLevel(
        config.log.level
        if not isinstance(config.log.level, str)
        else config.log.level.upper()
    )

    if config.dev:
        if os.environ.get("VIEW_PROD") is not None:
            Service.warning("VIEW_PROD is set but dev is set to true")

        format_warnings()
        weakref.finalize(self, self._finalize)

        if config.log.pretty_tracebacks:
            install(show_locals=True)

        rich_handler = sys.excepthook

        def _hook(tp: type[B], value: B, traceback: Traceback) -> None:
            rich_handler(tp, value, traceback)
            os.environ["_VIEW_CANCEL_FINALIZERS"] = "1"

            if isinstance(value, ViewError):
                if value.hint:
                    print(value.hint)

        sys.excepthook = _hook
        with suppress(UnsupportedOperation):
            faulthandler.enable()
    else:
        os.environ["VIEW_PROD"] = "1"

    if config.log.level == "debug":
        enable_debug()

    self.running = False

view.app.App.body(name: str, *tps: type[V], doc: str | None = None, default: V | None | _NoDefaultType = _NoDefault)

Set a body parameter.

Parameters:

Name	Type	Description	Default
name	str	Name of the parameter.	required
tps	type[V]	Types that can be passed to the server. If empty, any is used.	()
doc	str | None	Description of this body parameter.	None
default	V | None | _NoDefaultType	Default value to be used if not supplied.	_NoDefault

Source code in src/view/app.py

def body(
    self,
    name: str,
    *tps: type[V],
    doc: str | None = None,
    default: V | None | _NoDefaultType = _NoDefault,
):
    """Set a body parameter.

    Args:
        name: Name of the parameter.
        tps: Types that can be passed to the server. If empty, any is used.
        doc: Description of this body parameter.
        default: Default value to be used if not supplied.
    """

    def inner(func: RouteOrCallable) -> Route:
        route = body_impl(name, *tps, doc=doc, default=default)(func)
        self._push_route(route)
        return route

    return inner

view.app.App.delete(path: str, doc: str | None = None, *, cache_rate: int = -1)

Add a DELETE route.

Parameters:

Name	Type	Description	Default
path_or_route		The path to this route, or the route itself.	required
doc	str | None	The description of the route to be used in documentation.	None
cache_rate	int	Reload the cache for this route every x number of requests. -1 means to never cache.	-1

Example

from view import new_app

app = new_app()

@app.delete("/")
async def index():
    return "Hello, view.py!"

app.run()

Source code in src/view/app.py

def delete(self, path: str, doc: str | None = None, *, cache_rate: int = -1):
    """Add a DELETE route.

    Args:
        path_or_route: The path to this route, or the route itself.
        doc: The description of the route to be used in documentation.
        cache_rate: Reload the cache for this route every x number of requests. `-1` means to never cache.

    Example:
        ```py
        from view import new_app

        app = new_app()

        @app.delete("/")
        async def index():
            return "Hello, view.py!"

        app.run()
        ```
    """
    return self._method_wrapper(path, doc, cache_rate, delete)

view.app.App.docs(file: str | TextIO | Path | None = None, *, encoding: str = 'utf-8', overwrite: bool = True) -> str | None

Generate documentation for the app.

Source code in src/view/app.py

def docs(
    self,
    file: str | TextIO | Path | None = None,
    *,
    encoding: str = "utf-8",
    overwrite: bool = True,
) -> str | None:
    """Generate documentation for the app."""
    self.load()
    md = markdown_docs(self._docs)

    if not file:
        return md

    if isinstance(file, str):
        if not overwrite:
            Path(file).write_text(md, encoding=encoding)
        else:
            with open(file, "w", encoding=encoding) as f:
                f.write(md)
    elif isinstance(file, Path):
        if overwrite:
            with open(file, "w", encoding=encoding) as f:
                f.write(md)
        else:
            file.write_text(md)
    else:
        file.write(md)

view.app.App.get(path: str, doc: str | None = None, *, cache_rate: int = -1)

Add a GET route.

Parameters:

Name	Type	Description	Default
path_or_route		The path to this route, or the route itself.	required
doc	str | None	The description of the route to be used in documentation.	None
cache_rate	int	Reload the cache for this route every x number of requests. -1 means to never cache.	-1

Example

from view import new_app

app = new_app()

@app.get("/")
async def index():
    return "Hello, view.py!"

app.run()

Source code in src/view/app.py

def get(self, path: str, doc: str | None = None, *, cache_rate: int = -1):
    """Add a GET route.

    Args:
        path_or_route: The path to this route, or the route itself.
        doc: The description of the route to be used in documentation.
        cache_rate: Reload the cache for this route every x number of requests. `-1` means to never cache.

    Example:
        ```py
        from view import new_app

        app = new_app()

        @app.get("/")
        async def index():
            return "Hello, view.py!"

        app.run()
        ```
    """
    return self._method_wrapper(path, doc, cache_rate, get)

view.app.App.load(routes: list[Route] | None = None) -> None

Load the app. This is automatically called most of the time and should only be called manually during manual loading.

Parameters:

Name	Type	Description	Default
routes	list[Route] | None	Routes to load into the app.	None

Source code in src/view/app.py

def load(self, routes: list[Route] | None = None) -> None:
    """Load the app. This is automatically called most of the time and should only be called manually during manual loading.

    Args:
        routes: Routes to load into the app.
    """
    if self.loaded:
        if routes:
            finalize(routes, self)
        Internal.warning("load called twice")
        return

    if routes and (self.config.app.loader != "manual"):
        warnings.warn(_ROUTES_WARN_MSG)

    if self.config.app.loader == "filesystem":
        load_fs(self, self.config.app.loader_path)
    elif self.config.app.loader == "simple":
        load_simple(self, self.config.app.loader_path)
    elif self.config.app.loader == "patterns":
        load_patterns(self, self.config.app.loader_path)
    else:
        finalize([*(routes or ()), *self._manual_routes], self)

    self.loaded = True

    from .routing import RouteInput

    for r in self.loaded_routes:
        if not r.path:
            continue

        body = {}
        query = {}

        for i in r.inputs:
            if not isinstance(i, RouteInput):
                continue

            target = body if i.is_body else query
            target[i.name] = InputDoc(
                i.doc or "No description provided.", i.tp, i.default
            )

        if r.method:
            self._docs[(r.method.name, r.path)] = RouteDoc(
                r.doc or "No description provided.", body, query
            )
        else:
            self._docs[
                (tuple([i.name for i in r.method_list]) if r.method_list else (
                    "GET",
                    "POST",
                    "PUT",
                    "PATCH",
                    "DELETE",
                    "OPTIONS",
                ), r.path)] = RouteDoc(
                r.doc or "No description provided.", body, query
            )

view.app.App.options(path: str, doc: str | None = None, *, cache_rate: int = -1)

Add an OPTIONS route.

Parameters:

Name	Type	Description	Default
path_or_route		The path to this route, or the route itself.	required
doc	str | None	The description of the route to be used in documentation.	None
cache_rate	int	Reload the cache for this route every x number of requests. -1 means to never cache.	-1

Example

from view import new_app

app = new_app()

@app.options("/")
async def index():
    return "Hello, view.py!"

app.run()

Source code in src/view/app.py

def options(self, path: str, doc: str | None = None, *, cache_rate: int = -1):
    """Add an OPTIONS route.

    Args:
        path_or_route: The path to this route, or the route itself.
        doc: The description of the route to be used in documentation.
        cache_rate: Reload the cache for this route every x number of requests. `-1` means to never cache.

    Example:
        ```py
        from view import new_app

        app = new_app()

        @app.options("/")
        async def index():
            return "Hello, view.py!"

        app.run()
        ```
    """
    return self._method_wrapper(path, doc, cache_rate, options)

view.app.App.patch(path: str, doc: str | None = None, *, cache_rate: int = -1)

Add a PATCH route.

Parameters:

Name	Type	Description	Default
path_or_route		The path to this route, or the route itself.	required
doc	str | None	The description of the route to be used in documentation.	None
cache_rate	int	Reload the cache for this route every x number of requests. -1 means to never cache.	-1

Example

from view import new_app

app = new_app()

@app.patch("/")
async def index():
    return "Hello, view.py!"

app.run()

Source code in src/view/app.py

def patch(
    self,
    path: str,
    doc: str | None = None,
    *,
    cache_rate: int = -1,
):
    """Add a PATCH route.

    Args:
        path_or_route: The path to this route, or the route itself.
        doc: The description of the route to be used in documentation.
        cache_rate: Reload the cache for this route every x number of requests. `-1` means to never cache.

    Example:
        ```py
        from view import new_app

        app = new_app()

        @app.patch("/")
        async def index():
            return "Hello, view.py!"

        app.run()
        ```
    """
    return self._method_wrapper(path, doc, cache_rate, patch)

view.app.App.post(path: str, doc: str | None = None, *, cache_rate: int = -1)

Add a POST route.

Parameters:

Name	Type	Description	Default
path_or_route		The path to this route, or the route itself.	required
doc	str | None	The description of the route to be used in documentation.	None
cache_rate	int	Reload the cache for this route every x number of requests. -1 means to never cache.	-1

Example

from view import new_app

app = new_app()

@app.post("/")
async def index():
    return "Hello, view.py!"

app.run()

Source code in src/view/app.py

def post(self, path: str, doc: str | None = None, *, cache_rate: int = -1):
    """Add a POST route.

    Args:
        path_or_route: The path to this route, or the route itself.
        doc: The description of the route to be used in documentation.
        cache_rate: Reload the cache for this route every x number of requests. `-1` means to never cache.

    Example:
        ```py
        from view import new_app

        app = new_app()

        @app.post("/")
        async def index():
            return "Hello, view.py!"

        app.run()
        ```
    """
    return self._method_wrapper(path, doc, cache_rate, post)

view.app.App.put(path: str, doc: str | None = None, *, cache_rate: int = -1)

Add a PUT route.

Parameters:

Name	Type	Description	Default
path_or_route		The path to this route, or the route itself.	required
doc	str | None	The description of the route to be used in documentation.	None
cache_rate	int	Reload the cache for this route every x number of requests. -1 means to never cache.	-1

Example

from view import new_app

app = new_app()

@app.put("/")
async def index():
    return "Hello, view.py!"

app.run()

Source code in src/view/app.py

def put(self, path: str, doc: str | None = None, *, cache_rate: int = -1):
    """Add a PUT route.

    Args:
        path_or_route: The path to this route, or the route itself.
        doc: The description of the route to be used in documentation.
        cache_rate: Reload the cache for this route every x number of requests. `-1` means to never cache.

    Example:
        ```py
        from view import new_app

        app = new_app()

        @app.put("/")
        async def index():
            return "Hello, view.py!"

        app.run()
        ```
    """
    return self._method_wrapper(path, doc, cache_rate, put)

view.app.App.query(name: str, *tps: type[V], doc: str | None = None, default: V | None | _NoDefaultType = _NoDefault)

Set a query parameter.

Parameters:

Name	Type	Description	Default
name	str	Name of the parameter.	required
tps	type[V]	Types that can be passed to the server. If empty, any is used.	()
doc	str | None	Description of this query parameter.	None
default	V | None | _NoDefaultType	Default value to be used if not supplied.	_NoDefault

Source code in src/view/app.py

def query(
    self,
    name: str,
    *tps: type[V],
    doc: str | None = None,
    default: V | None | _NoDefaultType = _NoDefault,
):
    """Set a query parameter.

    Args:
        name: Name of the parameter.
        tps: Types that can be passed to the server. If empty, any is used.
        doc: Description of this query parameter.
        default: Default value to be used if not supplied.
    """

    def inner(func: RouteOrCallable) -> Route:
        route = query_impl(name, *tps, doc=doc, default=default)(func)
        self._push_route(route)
        return route

    return inner

view.app.App.route(path_or_route: str | None | RouteOrCallable = None, doc: str | None = None, *, cache_rate: int = -1, methods: Iterable[StrMethod] | None = None) -> Callable[[RouteOrCallable], Route]

Add a route that can be called with any method (or only specific methods).

Parameters:

Name	Type	Description	Default
path_or_route	str | None | RouteOrCallable	The path to this route, or the route itself.	None
doc	str | None	The description of the route to be used in documentation.	None
cache_rate	int	Reload the cache for this route every x number of requests. -1 means to never cache.	-1
methods	Iterable[StrMethod] | None	Methods that can be used to access this route. If this is None, then all methods are allowed.	None

Example

from view import route

@route("/", methods=("GET", "POST"))
async def index():
    return "Hello, view.py!"

Source code in src/view/app.py

def route(
    self,
    path_or_route: str | None | RouteOrCallable = None,
    doc: str | None = None,
    *,
    cache_rate: int = -1,
    methods: Iterable[StrMethod] | None = None
) -> Callable[[RouteOrCallable], Route]:
    """Add a route that can be called with any method (or only specific methods).

    Args:
        path_or_route: The path to this route, or the route itself.
        doc: The description of the route to be used in documentation.
        cache_rate: Reload the cache for this route every x number of requests. `-1` means to never cache.
        methods: Methods that can be used to access this route. If this is `None`, then all methods are allowed.

    Example:
        ```py
        from view import route

        @route("/", methods=("GET", "POST"))
        async def index():
            return "Hello, view.py!"
        ```
    """
    def inner(r: RouteOrCallable) -> Route:
        new_r = route_impl(path_or_route, doc, cache_rate=cache_rate, methods=methods)(r)
        self._push_route(new_r)
        return new_r

    return inner

view.app.App.run(*, fancy: bool | None = None) -> None

Run the app.

Source code in src/view/app.py

def run(self, *, fancy: bool | None = None) -> None:
    """Run the app."""
    if fancy is not None:
        self.config.log.fancy = fancy

    frame = inspect.currentframe()
    assert frame, "failed to get frame"
    assert frame.f_back, "frame has no f_back"

    back = frame.f_back
    base = os.path.basename(back.f_code.co_filename)
    app_path = self.config.app.app_path
    fname = app_path.split(":")[0]
    if base != fname:
        warnings.warn(
            f"ran app from {base}, but app path is {fname} in config",
        )

    if (not os.environ.get("_VIEW_RUN")) and (
        back.f_globals.get("__name__") == "__main__"
    ):
        self._run()
    else:
        Internal.info("called run, but env or scope prevented startup")

view.app.App.run_async(loop: asyncio.AbstractEventLoop | None = None) -> None

Run the app in an event loop.

Source code in src/view/app.py

def run_async(
    self,
    loop: asyncio.AbstractEventLoop | None = None,
) -> None:
    """Run the app in an event loop."""
    self._run((loop or asyncio.get_event_loop()).run_until_complete)

view.app.App.run_task(loop: asyncio.AbstractEventLoop | None = None) -> asyncio.Task[None]

Run the app as a task.

Source code in src/view/app.py

def run_task(
    self,
    loop: asyncio.AbstractEventLoop | None = None,
) -> asyncio.Task[None]:
    """Run the app as a task."""
    return self._run((loop or asyncio.get_event_loop()).create_task)

view.app.App.run_threaded(*, daemon: bool = True) -> Thread

Run the app in a thread.

Source code in src/view/app.py

def run_threaded(self, *, daemon: bool = True) -> Thread:
    """Run the app in a thread."""
    thread = Thread(target=self._run, daemon=daemon)
    thread.start()
    return thread

view.app.App.template(name: str | Path, directory: str | Path | None = _ConfigSpecified, engine: TemplateEngine | None = _ConfigSpecified, frame: Frame | None | _CurrentFrameType = _CurrentFrame, **parameters: Any) -> HTML async

Render a template with the specified engine. This returns a view.py HTML response.

Source code in src/view/app.py

async def template(
    self,
    name: str | Path,
    directory: str | Path | None = _ConfigSpecified,
    engine: TemplateEngine | None = _ConfigSpecified,
    frame: Frame | None | _CurrentFrameType = _CurrentFrame,
    **parameters: Any,
) -> HTML:
    """Render a template with the specified engine. This returns a view.py HTML response."""
    return await template(name, directory, engine, frame, app=self, **parameters)

view.app.App.test() async

Open the testing context.

Source code in src/view/app.py

@asynccontextmanager
async def test(self):
    """Open the testing context."""
    self.load()
    ctx = TestingContext(self.asgi_app_entry)
    try:
        yield ctx
    finally:
        await ctx.stop()

Launching Apps

Python libraries generally have two ways to run a web server:

• Running via the command line.
• Launching from Python itself (e.g. a server.start(...) function).

Both have their benefits and downsides, so view.py supports both out of the box. App comes with its run() method, and the view CLI has the view serve command.

Generally, you're going to want to add an app.run() to every view.py project, like so:

from view import new_app

app = new_app()
app.run()

This way, if you (or someone else) want to run your code programmatically, they can run it via something like python3 app.py. It's also more semantically clear that an app is going to start when you run that file.

If you prefer the CLI method, you can just run view serve and view.py will extract the app from the file itself, ignoring the run() call.

Note that this behavior is a double-edged sword, so be careful. When calling with run(), the Python script will never get past that line because the server will run indefinitely, but when using view serve it proceeds past it just fine since all it's doing is extracting the app, skipping run(). For example, take a look at this code:

from view import new_app

app = new_app()
app.run()
print("you called the app with view serve")  # this only runs when `view serve` is used

view.app.App.run(*, fancy: bool | None = None) -> None

Run the app.

Source code in src/view/app.py

def run(self, *, fancy: bool | None = None) -> None:
    """Run the app."""
    if fancy is not None:
        self.config.log.fancy = fancy

    frame = inspect.currentframe()
    assert frame, "failed to get frame"
    assert frame.f_back, "frame has no f_back"

    back = frame.f_back
    base = os.path.basename(back.f_code.co_filename)
    app_path = self.config.app.app_path
    fname = app_path.split(":")[0]
    if base != fname:
        warnings.warn(
            f"ran app from {base}, but app path is {fname} in config",
        )

    if (not os.environ.get("_VIEW_RUN")) and (
        back.f_globals.get("__name__") == "__main__"
    ):
        self._run()
    else:
        Internal.info("called run, but env or scope prevented startup")

Fancy Mode

View comes with something called "fancy mode", which is a fancy UI that shows when you run the app. If you would like to disable this, you can do one of two things:

• Disable the fancy setting in configuration.
• Pass fancy=False to run().

You should disable it in the configuration if you completely despise fancy mode and don't want to use it at all, but if you only want to temporarily turn it off (for example, if you're a view.py developer and need to see proper output) then pass fancy=False.

Getting the App

Circular Imports

If you've worked with big Python projects before, there's a good chance you've run into a circular import error. A circular import error occurs when two modules try to import each other. A view.py example of this problem would most likely be the main app file trying to import a route, but then that route tries to import the app.

Note

The below example uses routing, which if you're reading this for the first time you don't know how to use yet. Focus on the use of the app variable and not the routing itself.

# app.py
from view import new_app
from routes import my_route

app = new_app()
app.load([my_route])
app.run()

# routes.py
from view import get
from app import app

@app.get("/something")
def something():
    return "something"

@get("/")
def index():
    return "Hello, view.py"

View gives you a solution to this problem: get_app. get_app uses some magic internally to get you your App instance right then and there, no import required. It works similar to how you would use new_app:

from view import get_app

app = get_app()

@app.get("/")
def index():
    return "..."

view.app.get_app(*, address: int | None = None) -> App

Get the last app created by new_app.

Source code in src/view/app.py

def get_app(*, address: int | None = None) -> App:
    """Get the last app created by `new_app`."""
    env = os.environ.get("_VIEW_APP_ADDRESS")
    addr = address or env

    if (not addr) and (not env):
        raise BadEnvironmentError("no view app registered")

    app: App = ctypes.cast(int(addr), ctypes.py_object).value  # type: ignore
    ctypes.pythonapi.Py_IncRef(app)
    return app

Review

Every view.py project should contain a call to new_app. new_app does important things like loading your configuration, set's up finalization code, and letting the App instance be used by get_app.

Running an app can be done in two ways: programmatically via the App.run or through view serve command. However, every view.py app should contain an App.run to give the choice for running programmatically. By default, view.py has a fancy UI when running your app, which may be disabled via editing the config or passing fancy=False to run().

Finally, circular imports occur when two Python modules try to import each other, which can happen a lot in view when getting the app from the app file (especially in manual routing). To fix it, View provides a get_app function to get you your App instance without an import.