Respond with jackson deserialization error messages

api/src/features/ErrorFeature.kt

@@ -10,6 +10,9 @@ import io.ktor.utils.io.errors.*
 
 fun Application.handleErrors() {
     install(StatusPages) {
+
+        jacksonErrors()
+
         exception<IOException> {
             call.respond(HttpStatusCode.BadRequest)
         }

api/src/features/JacksonErrors.kt

@@ -0,0 +1,67 @@
+package be.vandewalleh.features
+
+import com.fasterxml.jackson.core.JsonParseException
+import com.fasterxml.jackson.core.JsonProcessingException
+import com.fasterxml.jackson.core.exc.InputCoercionException
+import com.fasterxml.jackson.databind.JsonMappingException
+import com.fasterxml.jackson.databind.exc.MismatchedInputException
+import com.fasterxml.jackson.databind.exc.UnrecognizedPropertyException
+import com.fasterxml.jackson.module.kotlin.MissingKotlinParameterException
+import io.ktor.application.*
+import io.ktor.features.*
+import io.ktor.http.*
+import io.ktor.response.*
+
+fun StatusPages.Configuration.jacksonErrors() {
+    exception<MismatchedInputException> {
+        val error = InvalidFormatError(it.path.firstOrNull()?.fieldName, it.targetType)
+        call.respond(HttpStatusCode.BadRequest, error)
+    }
+    exception<JsonParseException> {
+        val error = JsonParseError()
+        call.respond(HttpStatusCode.BadRequest, error)
+    }
+    exception<UnrecognizedPropertyException> {
+        val error = UnrecognizedPropertyError(it.path[0].fieldName)
+        call.respond(HttpStatusCode.BadRequest, error)
+    }
+    exception<MissingKotlinParameterException> {
+        val error = MissingKotlinParameterError(it.path[0].fieldName)
+        call.respond(HttpStatusCode.BadRequest, error)
+    }
+    exception<JsonProcessingException> {
+        call.respond(HttpStatusCode.BadRequest, JsonProcessingError())
+    }
+    exception<JsonMappingException> {
+        if (it.cause is InputCoercionException) {
+            return@exception call.respond(HttpStatusCode.BadRequest, OutOfRangeError(it.path[0].fieldName))
+        }
+        call.respond(HttpStatusCode.BadRequest, JsonProcessingError())
+    }
+}
+
+
+class InvalidFormatError(val value: Any?, targetType: Class<*>) {
+    val msg = "Wrong type"
+    val required = targetType.simpleName
+}
+
+class UnrecognizedPropertyError(val field: Any?) {
+    val msg = "Unrecognized field"
+}
+
+class MissingKotlinParameterError(val field: String) {
+    val msg = "Missing field"
+}
+
+class JsonProcessingError {
+    val msg = "An error occurred while processing JSON"
+}
+
+class JsonParseError {
+    val msg = "Invalid JSON"
+}
+
+class OutOfRangeError(val field: String) {
+    val msg = "Numeric value out of range"
+}