Exemples de Middleware

Des exemples pratiques pour construire et utiliser les middleware de Whoosh-NG.

1. Middleware de Logging

from whoosh.middleware.base import Middleware
from whoosh.middleware.context import MiddlewareContext

class LoggingMiddleware(Middleware):
    def before_search(self, context: MiddlewareContext) -> MiddlewareContext:
        print(f"[RECHERCHE] Requête: {context.query}")
        return context

    def after_search(self, context: MiddlewareContext) -> MiddlewareContext:
        if context.results is not None:
            print(f"[RÉSULTATS] {len(context.results)} résultats trouvés")
        return context

2. Middleware de Metrics

from whoosh.middleware.base import Middleware
from whoosh.middleware.context import MiddlewareContext

class MetricsMiddleware(Middleware):
    def __init__(self) -> None:
        self._metrics = {}

    def after_index(self, context: MiddlewareContext) -> MiddlewareContext:
        self._metrics["documents_indexés"] = self._metrics.get("documents_indexés", 0) + 1
        return context

    def after_search(self, context: MiddlewareContext) -> MiddlewareContext:
        self._metrics["recherches_executées"] = self._metrics.get("recherches_executées", 0) + 1
        return context

    def get_metrics(self) -> dict:
        return dict(self._metrics)

3. Middleware de Cache

from whoosh.middleware.base import Middleware
from whoosh.middleware.context import MiddlewareContext

class SearchCacheMiddleware(Middleware):
    def __init__(self) -> None:
        self._cache = {}

    def before_search(self, context: MiddlewareContext) -> MiddlewareContext:
        if context.query and str(context.query) in self._cache:
            context.metadata["_résultat_cache"] = self._cache[str(context.query)]
        return context

    def after_search(self, context: MiddlewareContext) -> MiddlewareContext:
        if context.query and context.results is not None:
            self._cache[str(context.query)] = context.results
        return context

4. Appliquer un Middleware

from whoosh.middleware.chain import MiddlewareChain
from whoosh.middleware.integration import apply_middleware_to_searcher

chain = MiddlewareChain([
    LoggingMiddleware(),
    MetricsMiddleware(),
])

with ix.searcher() as base_searcher:
    searcher = apply_middleware_to_searcher(base_searcher, chain.middlewares)
    results = searcher.search(query)

Points clés

Hook	Phase	Description
startup	Init	Appelé une fois à l'initialisation
shutdown	Nettoyage	Appelé à la fermeture
before_index	Indexation	Avant l'ajout d'un document
after_index	Indexation	Après l'ajout d'un document
before_delete	Suppression	Avant la suppression
after_delete	Suppression	Après la suppression
before_search	Recherche	Avant l'exécution de la requête
after_search	Recherche	Après le retour des résultats
on_error	Erreur	En cas d'exception
on_commit	Commit	Après writer.commit()