Interceptors wrap handler execution. They can transform responses, handle errors, or implement cross-cutting concerns like logging, caching, or metrics. Interceptors run after guards and pipes, and they can run logic both before and after the handler.

Basic Interceptor

from nestipy.common import Injectable, NestipyInterceptor
from nestipy.core import ExecutionContext
from nestipy.types_ import NextFn


@Injectable()
class LoggingInterceptor(NestipyInterceptor):
    async def intercept(self, context: ExecutionContext, next_fn: NextFn):
        print("Before handler")
        result = await next_fn()
        print("After handler")
        return result

Response Mapping Example

from nestipy.common import Injectable, NestipyInterceptor
from nestipy.core import ExecutionContext
from nestipy.types_ import NextFn


@Injectable()
class WrapResponseInterceptor(NestipyInterceptor):
    async def intercept(self, context: ExecutionContext, next_fn: NextFn):
        data = await next_fn()
        return {"data": data, "meta": {"ok": True}}

Apply Interceptors

Interceptors can be applied at the controller, method, module, or global level.

from nestipy.common import Controller, Post, UseInterceptors, Module, ModuleProviderDict
from nestipy.core import AppKey


@UseInterceptors(LoggingInterceptor)
@Controller("cats")
class CatsController:
    @UseInterceptors(LoggingInterceptor)
    @Post()
    async def create(self):
        pass


@Module(
    controllers=[CatsController],
    providers=[
        ModuleProviderDict(token=AppKey.APP_INTERCEPTOR, use_class=LoggingInterceptor)
    ],
)
class AppModule:
    pass

Global usage:

from nestipy.core import NestipyFactory

app = NestipyFactory.create(AppModule)
app.use_global_interceptors(LoggingInterceptor)

Tips

• Always call next_fn() to allow handler execution unless you intentionally short-circuit.
• Interceptors are ideal for shaping response format consistently.
• Keep interceptors stateless or use request scope for per-request state.