field_manager does not writes to a non list target field if extend_ta…

…rget_list (#616)

* update changelog
* add testcases
* add case for single source field to existing target field

CHANGELOG.md

@@ -16,6 +16,7 @@ This release limits the maximum python version to `3.12.3` because of the issue
 ### Bugfix
 
 * fixes a bug where it could happen that a config value could be overwritten by a default in a later configuration in a multi source config scenario
+* fixes a bug in the `field_manager` where extending a non list target leads to a processing failure
 
 ## 12.0.0
 

logprep/processor/field_manager/processor.py

@@ -137,9 +137,11 @@ def _write_to_single_target(self, args, extend_target_list, overwrite_target, ru
                 add_and_overwrite(event, target_field, source_fields_values)
                 return
 
-            case State(
-                extend=True, overwrite=False, single_source_element=False, target_is_list=False
-            ):
+            case State(extend=True, overwrite=False, target_is_list=False, target_is_none=True):
+                add_and_overwrite(event, target_field, source_fields_values)
+                return
+
+            case State(extend=True, overwrite=False, target_is_list=False):
                 source_fields_values = [target_field_value, *source_fields_values]
                 add_and_overwrite(event, target_field, source_fields_values)
                 return

tests/unit/processor/field_manager/test_field_manager.py

@@ -70,9 +70,7 @@
                 "delete_source_fields": True,
             },
         },
-        {
-            "message": "This is a message",
-        },
+        {"message": "This is a message"},
         {"new_field": ["This is a message"]},
     ),
     (
@@ -113,6 +111,25 @@
         },
         {"new_field": ["value1", "value2", "value3"]},
     ),
+    (
+        "moves multiple fields and replaces existing target field with list including the existing value",
+        {
+            "filter": "field1 OR field2 OR field3",
+            "field_manager": {
+                "source_fields": ["field1", "field2", "field3"],
+                "target_field": "new_field",
+                "extend_target_list": True,
+                "delete_source_fields": True,
+            },
+        },
+        {
+            "field1": "value1",
+            "field2": "value2",
+            "field3": "value3",
+            "new_field": "i exist",
+        },
+        {"new_field": ["i exist", "value1", "value2", "value3"]},
+    ),
     (
         "moves multiple fields and writes them to a existing list",
         {
@@ -436,6 +453,42 @@
         {"existing_list": ["hello", "world"], "foo": "bar", "test": "value"},
         {"existing_list": ["hello", "world", "bar", "value"], "foo": "bar", "test": "value"},
     ),
+    (
+        "Convert existing target to list",
+        {
+            "filter": "message",
+            "field_manager": {
+                "source_fields": ["message"],
+                "target_field": "new_field",
+                "extend_target_list": True,
+            },
+        },
+        {"message": "Value B", "new_field": "Value A"},
+        {"message": "Value B", "new_field": ["Value A", "Value B"]},
+    ),
+    (
+        "Convert existing target to list with multiple source fields",
+        {
+            "filter": "field1 OR field2 OR field3",
+            "field_manager": {
+                "source_fields": ["field1", "field2", "field3"],
+                "target_field": "new_field",
+                "extend_target_list": True,
+            },
+        },
+        {
+            "field1": "Value B",
+            "field2": "Value C",
+            "field3": "Value D",
+            "new_field": "Value A",
+        },
+        {
+            "field1": "Value B",
+            "field2": "Value C",
+            "field3": "Value D",
+            "new_field": ["Value A", "Value B", "Value C", "Value D"],
+        },
+    ),
 ]
 
 failure_test_cases = [