Route Data Validation
+Route data can be anything, so it's easy to do mistakes. Accidentally using a :role key instead of :roles might render the whole routing app without any authorization in place.
To fail fast, we could use the custom :coerce and :compile hooks to apply data validation and throw exceptions on first sighted problem.
But there is a better way. Router also has a :validation hook to validate the whole route tree after it's successfuly compiled. It expects a 2-arity function routes opts => () that can side-effect in case of validation errors.
clojure.spec
+Namespace reitit.spec contains specs for main parts of reitit.core and a helper function validate-spec! that runs spec validation for all route data and throws an exception if any errors are found.
A Router with invalid route data:
+(require '[reitit.core :as r])
+
+(r/router
+ ["/api" {:handler "identity"}])
+; #object[reitit.core$...]
+Fails fast with clojure.spec validation turned on:
(require '[reitit.spec :as rs])
+
+(r/router
+ ["/api" {:handler "identity"}]
+ {:validate rs/validate-spec!})
+; CompilerException clojure.lang.ExceptionInfo: Invalid route data:
+;
+; -- On route -----------------------
+;
+; "/api"
+;
+; In: [:handler] val: "identity" fails spec: :reitit.spec/handler at: [:handler] predicate: fn?
+;
+; {:problems (#reitit.spec.Problem{:path "/api", :scope nil, :data {:handler "identity"}, :spec :reitit.spec/default-data, :problems #:clojure.spec.alpha{:problems ({:path [:handler], :pred clojure.core/fn?, :val "identity", :via [:reitit.spec/default-data :reitit.spec/handler], :in [:handler]}), :spec :reitit.spec/default-data, :value {:handler "identity"}}})}, compiling: ...
+Customizing spec validation
+rs/validate-spec! reads the following router options:
| key | +description | +
|---|---|
:spec |
+the spec to verify the route data (default ::rs/default-data) |
+
::rs/explain |
+custom explain function (default clojure.spec.alpha/explain-str) |
+
NOTE: clojure.spec implicitly validates all values with fully-qualified keys if specs exist with the same name.
Below is an example of using expound to pretty-print route data problems.
+(require '[clojure.spec.alpha :as s])
+(require '[expound.alpha :as e])
+
+(s/def ::role #{:admin :manager})
+(s/def ::roles (s/coll-of ::role :into #{}))
+
+(r/router
+ ["/api" {:handler identity
+ ::roles #{:adminz}}]
+ {::rs/explain e/expound-str
+ :validate rs/validate-spec!})
+; CompilerException clojure.lang.ExceptionInfo: Invalid route data:
+;
+; -- On route -----------------------
+;
+; "/api"
+;
+; -- Spec failed --------------------
+;
+; {:handler ..., :user/roles #{:adminz}}
+; ^^^^^^^
+;
+; should be one of: `:admin`,`:manager`
+;
+; -- Relevant specs -------
+;
+; :user/role:
+; #{:admin :manager}
+; :user/roles:
+; (clojure.spec.alpha/coll-of :user/role :into #{})
+; :reitit.spec/default-data:
+; (clojure.spec.alpha/keys
+; :opt-un
+; [:reitit.spec/name :reitit.spec/handler])
+;
+; -------------------------
+; Detected 1 error
+;
+; {:problems (#reitit.spec.Problem{:path "/api", :scope nil, :data {:handler #object[clojure.core$identity 0x15b59b0e "clojure.core$identity@15b59b0e"], :user/roles #{:adminz}}, :spec :reitit.spec/default-data, :problems #:clojure.spec.alpha{:problems ({:path [:user/roles], :pred #{:admin :manager}, :val :adminz, :via [:reitit.spec/default-data :user/roles :user/role], :in [:user/roles 0]}), :spec :reitit.spec/default-data, :value {:handler #object[clojure.core$identity 0x15b59b0e "clojure.core$identity@15b59b0e"], :user/roles #{:adminz}}}})}, compiling: ...
+Explicitly requiring a ::roles key in a route data:
(r/router
+ ["/api" {:handler identity}]
+ {:spec (s/merge (s/keys :req [::roles]) ::rs/default-data)
+ ::rs/explain e/expound-str
+ :validate rs/validate-spec!})
+; CompilerException clojure.lang.ExceptionInfo: Invalid route data:
+;
+; -- On route -----------------------
+;
+; "/api"
+;
+; -- Spec failed --------------------
+;
+; {:handler
+; #object[clojure.core$identity 0x15b59b0e "clojure.core$identity@15b59b0e"]}
+;
+; should contain key: `:user/roles`
+;
+; | key | spec |
+; |-------------+----------------------------------------|
+; | :user/roles | (coll-of #{:admin :manager} :into #{}) |
+;
+;
+;
+; -------------------------
+; Detected 1 error
+;
+; {:problems (#reitit.spec.Problem{:path "/api", :scope nil, :data {:handler #object[clojure.core$identity 0x15b59b0e "clojure.core$identity@15b59b0e"]}, :spec #object[clojure.spec.alpha$merge_spec_impl$reify__2124 0x7461744b "clojure.spec.alpha$merge_spec_impl$reify__2124@7461744b"], :problems #:clojure.spec.alpha{:problems ({:path [], :pred (clojure.core/fn [%] (clojure.core/contains? % :user/roles)), :val {:handler #object[clojure.core$identity 0x15b59b0e "clojure.core$identity@15b59b0e"]}, :via [], :in []}), :spec #object[clojure.spec.alpha$merge_spec_impl$reify__2124 0x7461744b "clojure.spec.alpha$merge_spec_impl$reify__2124@7461744b"], :value {:handler #object[clojure.core$identity 0x15b59b0e "clojure.core$identity@15b59b0e"]}}})}, compiling:(/Users/tommi/projects/metosin/reitit/test/cljc/reitit/spec_test.cljc:151:1)
+