Avoid exceptions from jackson serialization of processValues that contain a map with a null key

qqq-middleware-javalin/src/main/java/com/kingsrook/qqq/backend/javalin/QJavalinProcessHandler.java

@@ -352,6 +352,8 @@ public class QJavalinProcessHandler
       Map<String, Object> resultForCaller    = new HashMap<>();
       Exception           returningException = null;
 
+      String processName = context.pathParam("processName");
+
       try
       {
          if(processUUID == null)
@@ -360,7 +362,6 @@ public class QJavalinProcessHandler
          }
          resultForCaller.put("processUUID", processUUID);
 
-         String processName = context.pathParam("processName");
          LOG.info(startAfterStep == null ? "Initiating process [" + processName + "] [" + processUUID + "]"
             : "Resuming process [" + processName + "] [" + processUUID + "] after step [" + startAfterStep + "]");
 
@@ -441,10 +442,30 @@ public class QJavalinProcessHandler
       // negative side-effects - but be aware.                                         //
       // One could imagine that we'd need this to be configurable in the future?       //
       ///////////////////////////////////////////////////////////////////////////////////
-      context.result(JsonUtils.toJson(resultForCaller, mapper ->
+      try
       {
-         mapper.setSerializationInclusion(JsonInclude.Include.ALWAYS);
+         String json = JsonUtils.toJson(resultForCaller, mapper ->
-      }));
+         {
+            mapper.setSerializationInclusion(JsonInclude.Include.ALWAYS);
+
+            /////////////////////////////////////////////////////////////////////////////////////////////////////////////
+            // use this custom serializer to convert null map-keys to empty-strings (rather than having an exception!) //
+            /////////////////////////////////////////////////////////////////////////////////////////////////////////////
+            mapper.getSerializerProvider().setNullKeySerializer(JsonUtils.nullKeyToEmptyStringSerializer);
+         });
+         context.result(json);
+      }
+      catch(Exception e)
+      {
+         /////////////////////////////////////////////////////////////////////////////////////////////////////
+         // related to the change above - we've seen at least one new error that can come from the          //
+         // Include.ALWAYS change (a null key in a map -> jackson exception).  So, try-catch around         //
+         // the above serialization, and if it does throw, log, but continue trying a default serialization //
+         // as that is probably preferable to an exception for the caller...                                //
+         /////////////////////////////////////////////////////////////////////////////////////////////////////
+         LOG.warn("Error deserializing process results with serializationInclusion:ALWAYS - will retry with default settings", e, logPair("processName", processName), logPair("processUUID", processUUID));
+         context.result(JsonUtils.toJson(resultForCaller));
+      }
    }
 
 

qqq-middleware-javalin/src/main/java/com/kingsrook/qqq/middleware/javalin/specs/v1/responses/ProcessInitOrStepOrStatusResponseV1.java

@@ -26,6 +26,7 @@ import java.io.Serializable;
 import java.util.List;
 import java.util.Map;
 import java.util.stream.Collectors;
+import com.fasterxml.jackson.annotation.JsonIgnore;
 import com.kingsrook.qqq.middleware.javalin.executors.io.ProcessInitOrStepOrStatusOutputInterface;
 import com.kingsrook.qqq.middleware.javalin.schemabuilder.SchemaBuilder;
 import com.kingsrook.qqq.middleware.javalin.schemabuilder.ToSchema;
@@ -117,6 +118,7 @@ public class ProcessInitOrStepOrStatusResponseV1 implements ProcessInitOrStepOrS
        ** Getter for values
        **
        *******************************************************************************/
+      @JsonIgnore // we are doing custom serialization of the values map, so mark as ignore.
       public Map<String, Serializable> getValues()
       {
          return values;

qqq-middleware-javalin/src/main/java/com/kingsrook/qqq/middleware/javalin/specs/v1/utils/ProcessSpecUtilsV1.java

@@ -183,6 +183,14 @@ public class ProcessSpecUtilsV1
                String       name  = valueEntry.getKey();
                Serializable value = valueEntry.getValue();
 
+               ///////////////////////////////////////////////////////////////////////////////////////////////////////
+               // follow the strategy that we use for JsonUtils.nullKeyToEmptyStringSerializer in this rare case... //
+               ///////////////////////////////////////////////////////////////////////////////////////////////////////
+               if(name == null)
+               {
+                  name = "";
+               }
+
                Serializable valueToMakeIntoJson = value;
                if(value instanceof String s)
                {
@@ -213,11 +221,31 @@ public class ProcessSpecUtilsV1
                   valueToMakeIntoJson = new WidgetBlock(abstractBlockWidgetData);
                }
 
-               String valueAsJsonString = JsonUtils.toJson(valueToMakeIntoJson, mapper ->
+               ///////////////////////////////////////////////
+               // ok now, make the value into a JSON string //
+               ///////////////////////////////////////////////
+               String valueAsJsonString;
+               try
                {
-                  mapper.setSerializationInclusion(JsonInclude.Include.ALWAYS);
+                  valueAsJsonString = JsonUtils.toJson(valueToMakeIntoJson, mapper ->
-               });
+                  {
+                     mapper.setSerializationInclusion(JsonInclude.Include.ALWAYS);
 
+                     /////////////////////////////////////////////////////////////////////////////////////////////////////////////
+                     // use this custom serializer to convert null map-keys to empty-strings (rather than having an exception!) //
+                     /////////////////////////////////////////////////////////////////////////////////////////////////////////////
+                     mapper.getSerializerProvider().setNullKeySerializer(JsonUtils.nullKeyToEmptyStringSerializer);
+                  });
+               }
+               catch(Exception e)
+               {
+                  LOG.warn("Error deserializing process results with serializationInclusion:ALWAYS - will retry with default settings", e);
+                  valueAsJsonString = JsonUtils.toJson(valueToMakeIntoJson);
+               }
+
+               /////////////////////////////////////////////////////////////////////////////////////////////////////////
+               // THEN - make it back into a JSONObject or JSONArray, and add it to the valuesAsJsonObject JSONObject //
+               /////////////////////////////////////////////////////////////////////////////////////////////////////////
                if(valueAsJsonString.startsWith("["))
                {
                   valuesAsJsonObject.put(name, new JSONArray(valueAsJsonString));

qqq-middleware-javalin/src/test/java/com/kingsrook/qqq/backend/javalin/QJavalinProcessHandlerTest.java

@@ -655,4 +655,28 @@ class QJavalinProcessHandlerTest extends QJavalinTestBase
       assertEquals(200, response.getStatus());
    }
 
+
+
+   /*******************************************************************************
+    ** test running a process who has a value with a null key.
+    *
+    ** This was a regression - that threw an exception from jackson at one point in time.
+    **
+    ** Note:  ported to v1
+    *******************************************************************************/
+   @Test
+   public void test_processPutsNullKeyInMap()
+   {
+      HttpResponse<String> response = Unirest.get(BASE_URL + "/processes/" + TestUtils.PROCESS_NAME_PUTS_NULL_KEY_IN_MAP + "/init").asString();
+      assertEquals(200, response.getStatus());
+      JSONObject jsonObject = JsonUtils.toJSONObject(response.getBody());
+      assertNotNull(jsonObject);
+      JSONObject values = jsonObject.getJSONObject("values");
+      JSONObject mapWithNullKey = values.getJSONObject("mapWithNullKey");
+      assertTrue(mapWithNullKey.has("")); // null key currently set to become empty-string key...
+      assertEquals("hadNullKey", mapWithNullKey.getString(""));
+      assertTrue(mapWithNullKey.has("one"));
+      assertEquals("1", mapWithNullKey.getString("one"));
+   }
+
 }

qqq-middleware-javalin/src/test/java/com/kingsrook/qqq/backend/javalin/TestUtils.java

@@ -25,6 +25,7 @@ package com.kingsrook.qqq.backend.javalin;
 import java.io.InputStream;
 import java.nio.charset.StandardCharsets;
 import java.sql.Connection;
+import java.util.HashMap;
 import java.util.List;
 import java.util.Objects;
 import java.util.Optional;
@@ -53,6 +54,7 @@ import com.kingsrook.qqq.backend.core.model.metadata.QBackendMetaData;
 import com.kingsrook.qqq.backend.core.model.metadata.QInstance;
 import com.kingsrook.qqq.backend.core.model.metadata.authentication.QAuthenticationMetaData;
 import com.kingsrook.qqq.backend.core.model.metadata.code.QCodeReference;
+import com.kingsrook.qqq.backend.core.model.metadata.code.QCodeReferenceLambda;
 import com.kingsrook.qqq.backend.core.model.metadata.code.QCodeType;
 import com.kingsrook.qqq.backend.core.model.metadata.dashboard.QWidgetMetaData;
 import com.kingsrook.qqq.backend.core.model.metadata.fields.AdornmentType;
@@ -112,6 +114,8 @@ public class TestUtils
    public static final String PROCESS_NAME_SIMPLE_THROW             = "simpleThrow";
    public static final String PROCESS_NAME_SLEEP_INTERACTIVE        = "sleepInteractive";
 
+   public static final String PROCESS_NAME_PUTS_NULL_KEY_IN_MAP = "putsNullKeyInMap";
+
    public static final String STEP_NAME_SLEEPER = "sleeper";
    public static final String STEP_NAME_THROWER = "thrower";
 
@@ -177,6 +181,7 @@ public class TestUtils
       qInstance.addProcess(defineProcessGreetPeopleInteractive());
       qInstance.addProcess(defineProcessSimpleSleep());
       qInstance.addProcess(defineProcessScreenThenSleep());
+      qInstance.addProcess(defineProcessPutsNullKeyInMap());
       qInstance.addProcess(defineProcessSimpleThrow());
       qInstance.addReport(definePersonsReport());
       qInstance.addPossibleValueSource(definePossibleValueSourcePerson());
@@ -554,6 +559,26 @@ public class TestUtils
 
 
 
+
+   /*******************************************************************************
+    ** Define an interactive version of the 'greet people' process
+    *******************************************************************************/
+   private static QProcessMetaData defineProcessPutsNullKeyInMap()
+   {
+      return new QProcessMetaData()
+         .withName(PROCESS_NAME_PUTS_NULL_KEY_IN_MAP)
+         .withTableName(TABLE_NAME_PERSON)
+         .withStep(new QBackendStepMetaData().withName("step")
+            .withCode(new QCodeReferenceLambda<BackendStep>((runBackendStepInput, runBackendStepOutput) ->
+            {
+               HashMap<String, String> mapWithNullKey = new HashMap<>();
+               mapWithNullKey.put(null, "hadNullKey");
+               mapWithNullKey.put("one", "1");
+               runBackendStepOutput.addValue("mapWithNullKey", mapWithNullKey);
+            })));
+   }
+
+
    /*******************************************************************************
     ** Define a process with just one step that sleeps and then throws
     *******************************************************************************/

qqq-middleware-javalin/src/test/java/com/kingsrook/qqq/middleware/javalin/specs/v1/ProcessInitSpecV1Test.java

@@ -216,4 +216,26 @@ class ProcessInitSpecV1Test extends SpecTestBase
       // todo - in a higher-level test, resume test_processInitGoingAsync at the // request job status before sleep is done // line
    }
 
+
+   /*******************************************************************************
+    **
+    *******************************************************************************/
+   @Test
+   void testProcessPutsNullKeyInMap()
+   {
+      HttpResponse<String> response = Unirest.post(getBaseUrlAndPath() + "/processes/" + TestUtils.PROCESS_NAME_PUTS_NULL_KEY_IN_MAP + "/init")
+         .multiPartContent()
+         .asString();
+
+      assertEquals(200, response.getStatus());
+      JSONObject jsonObject = JsonUtils.toJSONObject(response.getBody());
+
+      JSONObject values = jsonObject.getJSONObject("values");
+      JSONObject mapWithNullKey = values.getJSONObject("mapWithNullKey");
+      assertTrue(mapWithNullKey.has("")); // null key currently set to become empty-string key...
+      assertEquals("hadNullKey", mapWithNullKey.getString(""));
+      assertTrue(mapWithNullKey.has("one"));
+      assertEquals("1", mapWithNullKey.getString("one"));
+   }
+
 }