Add :valid-payload? function

3 files changed, 17 insertions, 0 deletions

diff --git a/README.md b/README.md
index 314c779..7e49431 100644
--- a/README.md
+++ b/README.md
@@ -146,6 +146,8 @@ the payload. It can be added like this:
   ; An optional map of queue opts
   {:allow-cas-failure? true ; Treat [:db.cas ...] failures as success. This is one way for the
                             ; consumer function to ensure idempotence.
+   :valid-payload? (fn [payload] (some? (:id payload))) ; Function that verifies payload. Should return truthy for valid payloads.
+                                                        ; The default function always returns true.
    :max-retries 10})        ; Specify maximum number of times an item will be retried. Default: 100
 ```
 
diff --git a/src/com/github/ivarref/yoltq/impl.clj b/src/com/github/ivarref/yoltq/impl.clj
index 02cc102..8b75fc3 100644
--- a/src/com/github/ivarref/yoltq/impl.clj
+++ b/src/com/github/ivarref/yoltq/impl.clj
@@ -40,6 +40,7 @@
   (if-let [q-config (get-in config [:handlers queue-name])]
     (let [id (u/squuid)
           depends-on (get q-config :depends-on (fn [_] nil))
+          valid-payload? (get q-config :valid-payload? (fn [_] true))
           opts (merge
                  (when-let [deps (depends-on payload)]
                    {:depends-on deps})
@@ -49,6 +50,9 @@
                                     {}
                                     (or capture-bindings []))
                             (pr-str-safe :capture-bindings))]
+      (when-not (valid-payload? payload)
+        (log/error "Payload was not valid. Payload was:" payload)
+        (throw (ex-info (str "Payload was not valid: " payload) {:payload payload})))
       (log/debug "queue item" (str id) "for queue" queue-name "is pending status" u/status-init)
       (merge
         {:com.github.ivarref.yoltq/id         id
diff --git a/test/com/github/ivarref/yoltq/virtual_test.clj b/test/com/github/ivarref/yoltq/virtual_test.clj
index 8f7b454..acd3eb7 100644
--- a/test/com/github/ivarref/yoltq/virtual_test.clj
+++ b/test/com/github/ivarref/yoltq/virtual_test.clj
@@ -331,3 +331,14 @@
     (yq/add-consumer! :a identity)
     (timbre/with-level :fatal
       (is (thrown? Exception @(d/transact conn [(yq/put :a {:broken #'=})]))))))
+
+
+(deftest payload-verifier
+  (let [conn (u/empty-conn)]
+    (yq/init! {:conn conn})
+    (yq/add-consumer! :q identity
+                      {:valid-payload? (fn [{:keys [id]}]
+                                         (some? id))})
+    @(d/transact conn [(yq/put :q {:id "a"})])
+    (timbre/with-level :fatal
+                       (is (thrown? Exception @(d/transact conn [(yq/put :q {})]))))))
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