diff --git a/doc/basics/error_messages.md b/doc/basics/error_messages.md index 2e903702..4a29539a 100644 --- a/doc/basics/error_messages.md +++ b/doc/basics/error_messages.md @@ -48,3 +48,7 @@ Behind the scenes, both error formatters are backed by a multimethod, so they ar ## More examples See the [validating route data](route_data_validation.md) page. + +## Runtime Exception + +See [Exception Handling with Ring](../ring/exceptions.md). diff --git a/doc/cljdoc.edn b/doc/cljdoc.edn index 56eda47f..d691bbfd 100644 --- a/doc/cljdoc.edn +++ b/doc/cljdoc.edn @@ -39,6 +39,7 @@ ["Data-driven Middleware" {:file "doc/ring/data_driven_middleware.md"}] ["Transforming Middleware Chain" {:file "doc/ring/transforming_middleware_chain.md"}] ["Middleware Registry" {:file "doc/ring/middleware_registry.md"}] + ["Exception Handling with Ring" {:file "doc/ring/exceptions.md"}] ["Default Middleware" {:file "doc/ring/default_middleware.md"}] ["Pluggable Coercion" {:file "doc/ring/coercion.md"}] ["Route Data Validation" {:file "doc/ring/route_data_validation.md"}] diff --git a/doc/ring/default_middleware.md b/doc/ring/default_middleware.md index 2ed9f859..b8393529 100644 --- a/doc/ring/default_middleware.md +++ b/doc/ring/default_middleware.md @@ -21,107 +21,7 @@ Any Ring middleware can be used with `reitit-ring`, but using data-driven middle ## Exception Handling -A polished version of [compojure-api](https://github.com/metosin/compojure-api) exception handling. Catches all exceptions and invokes configured exception handler. - -```clj -(require '[reitit.ring.middleware.exception :as exception]) -``` - -### `exception/exception-middleware` - -A preconfigured middleware using `exception/default-handlers`. Catches: - -* Request & response [Coercion](coercion.md) exceptions -* [Muuntaja](https://github.com/metosin/muuntaja) decode exceptions -* Exceptions with `:type` of `:reitit.ring/response`, returning `:response` key from `ex-data`. -* Safely all other exceptions - -```clj -(require '[reitit.ring :as ring]) - -(def app - (ring/ring-handler - (ring/router - ["/fail" (fn [_] (throw (Exception. "fail")))] - {:data {:middleware [exception/exception-middleware]}}))) - -(app {:request-method :get, :uri "/fail"}) -;{:status 500 -; :body {:type "exception" -; :class "java.lang.Exception"}} -``` - -### `exception/create-exception-middleware` - -Creates the exception-middleware with custom options. Takes a map of `identifier => exception request => response` that is used to select the exception handler for the thrown/raised exception identifier. Exception identifier is either a `Keyword` or a Exception Class. - -The following handlers are available by default: - -| key | description -|--------------------------------------|------------- -| `:reitit.ring/response` | value in ex-data key `:response` will be returned -| `:muuntaja/decode` | handle Muuntaja decoding exceptions -| `:reitit.coercion/request-coercion` | request coercion errors (http 400 response) -| `:reitit.coercion/response-coercion` | response coercion errors (http 500 response) -| `::exception/default` | a default exception handler if nothing else matched (default `exception/default-handler`). -| `::exception/wrap` | a 3-arity handler to wrap the actual handler `handler exception request => response` (no default). - -The handler is selected from the options map by exception identifier in the following lookup order: - -1) `:type` of exception ex-data -2) Class of exception -3) `:type` ancestors of exception ex-data -4) Super Classes of exception -5) The ::default handler - -```clj -;; type hierarchy -(derive ::error ::exception) -(derive ::failure ::exception) -(derive ::horror ::exception) - -(defn handler [message exception request] - {:status 500 - :body {:message message - :exception (.getClass exception) - :data (ex-data exception) - :uri (:uri request)}}) - -(def exception-middleware - (exception/create-exception-middleware - (merge - exception/default-handlers - {;; ex-data with :type ::error - ::error (partial handler "error") - - ;; ex-data with ::exception or ::failure - ::exception (partial handler "exception") - - ;; SQLException and all it's child classes - java.sql.SQLException (partial handler "sql-exception") - - ;; override the default handler - ::exception/default (partial handler "default") - - ;; print stack-traces for all exceptions - ::exception/wrap (fn [handler e request] - (println "ERROR" (pr-str (:uri request))) - (handler e request))}))) - -(def app - (ring/ring-handler - (ring/router - ["/fail" (fn [_] (throw (ex-info "fail" {:type ::failue})))] - {:data {:middleware [exception-middleware]}}))) - -(app {:request-method :get, :uri "/fail"}) -; ERROR "/fail" -; => {:status 500, -; :body {:message "default" -; :exception clojure.lang.ExceptionInfo -; :data {:type :user/failue} -; :uri "/fail"}} -``` +See [Exception Handling with Ring](exceptions.md). ## Content Negotiation diff --git a/doc/ring/exceptions.md b/doc/ring/exceptions.md new file mode 100644 index 00000000..62106ed4 --- /dev/null +++ b/doc/ring/exceptions.md @@ -0,0 +1,107 @@ +# Exception Handling with Ring + +```clj +[metosin/reitit-middleware "0.3.6"] +``` + +Exceptions thrown in router creation can be [handled with custom exception handler](../basics/error_messages.md). By default, exceptions thrown at runtime from a handler or a middleware are not caught by the `reitit.ring/ring-handler`. A good practise is a have an top-level exception handler to log and format the errors for clients. + +```clj +(require '[reitit.ring.middleware.exception :as exception]) +``` + +### `exception/exception-middleware` + +A preconfigured middleware using `exception/default-handlers`. Catches: + +* Request & response [Coercion](coercion.md) exceptions +* [Muuntaja](https://github.com/metosin/muuntaja) decode exceptions +* Exceptions with `:type` of `:reitit.ring/response`, returning `:response` key from `ex-data`. +* Safely all other exceptions + +```clj +(require '[reitit.ring :as ring]) + +(def app + (ring/ring-handler + (ring/router + ["/fail" (fn [_] (throw (Exception. "fail")))] + {:data {:middleware [exception/exception-middleware]}}))) + +(app {:request-method :get, :uri "/fail"}) +;{:status 500 +; :body {:type "exception" +; :class "java.lang.Exception"}} +``` + +### `exception/create-exception-middleware` + +Creates the exception-middleware with custom options. Takes a map of `identifier => exception request => response` that is used to select the exception handler for the thrown/raised exception identifier. Exception identifier is either a `Keyword` or a Exception Class. + +The following handlers are available by default: + +| key | description +|--------------------------------------|------------- +| `:reitit.ring/response` | value in ex-data key `:response` will be returned +| `:muuntaja/decode` | handle Muuntaja decoding exceptions +| `:reitit.coercion/request-coercion` | request coercion errors (http 400 response) +| `:reitit.coercion/response-coercion` | response coercion errors (http 500 response) +| `::exception/default` | a default exception handler if nothing else matched (default `exception/default-handler`). +| `::exception/wrap` | a 3-arity handler to wrap the actual handler `handler exception request => response` (no default). + +The handler is selected from the options map by exception identifier in the following lookup order: + +1) `:type` of exception ex-data +2) Class of exception +3) `:type` ancestors of exception ex-data +4) Super Classes of exception +5) The ::default handler + +```clj +;; type hierarchy +(derive ::error ::exception) +(derive ::failure ::exception) +(derive ::horror ::exception) + +(defn handler [message exception request] + {:status 500 + :body {:message message + :exception (.getClass exception) + :data (ex-data exception) + :uri (:uri request)}}) + +(def exception-middleware + (exception/create-exception-middleware + (merge + exception/default-handlers + {;; ex-data with :type ::error + ::error (partial handler "error") + + ;; ex-data with ::exception or ::failure + ::exception (partial handler "exception") + + ;; SQLException and all it's child classes + java.sql.SQLException (partial handler "sql-exception") + + ;; override the default handler + ::exception/default (partial handler "default") + + ;; print stack-traces for all exceptions + ::exception/wrap (fn [handler e request] + (println "ERROR" (pr-str (:uri request))) + (handler e request))}))) + +(def app + (ring/ring-handler + (ring/router + ["/fail" (fn [_] (throw (ex-info "fail" {:type ::failue})))] + {:data {:middleware [exception-middleware]}}))) + +(app {:request-method :get, :uri "/fail"}) +; ERROR "/fail" +; => {:status 500, +; :body {:message "default" +; :exception clojure.lang.ExceptionInfo +; :data {:type :user/failue} +; :uri "/fail"}} +```