diff --git a/api/src/core/get_value.py b/api/src/core/get_value.py
index aff4788..6acec5a 100644
--- a/api/src/core/get_value.py
+++ b/api/src/core/get_value.py
@@ -1,15 +1,14 @@
-import ast
-from typing import Type, Optional, Any
+from typing import Type, Optional
 
 from core.typing import T
 
 
 def get_value(
-    source: dict,
-    key: str,
-    cast_type: Type[T],
-    default: Optional[T] = None,
-    list_delimiter: str = ",",
+        source: dict,
+        key: str,
+        cast_type: Type[T],
+        default: Optional[T] = None,
+        list_delimiter: str = ",",
 ) -> Optional[T]:
     """
     Get value from source dictionary and cast it to a specified type.
@@ -22,33 +21,33 @@ def get_value(
     :rtype: Optional[T]
     """
 
-    if key in source:
-        value = source[key]
-        if isinstance(
+    if key not in source:
+        return default
+
+    value = source[key]
+    if isinstance(
             value,
             cast_type if not hasattr(cast_type, "__origin__") else cast_type.__origin__,
-        ):
-            return value
+    ):
+        return value
 
-        try:
-            if cast_type == bool:
-                return value.lower() in ["true", "1"]
+    try:
+        if cast_type == bool:
+            return value.lower() in ["true", "1"]
 
-            if (
-                cast_type
-                if not hasattr(cast_type, "__origin__")
-                else cast_type.__origin__
-            ) == list:
-                subtype = (
-                    cast_type.__args__[0] if hasattr(cast_type, "__args__") else None
-                )
-                value = value.split(list_delimiter)
-                return [
-                    subtype(item) if subtype is not None else item for item in value
-                ]
+        if (
+                cast_type if not hasattr(cast_type, "__origin__") else cast_type.__origin__
+        ) == list:
+            if not (value.startswith("[") and value.endswith("]")) and list_delimiter not in value:
+                raise ValueError("List values must be enclosed in square brackets or use a delimiter.")
 
-            return cast_type(value)
-        except (ValueError, TypeError):
-            return default
-    else:
+            if value.startswith("[") and value.endswith("]"):
+                value = value[1:-1]
+
+            value = value.split(list_delimiter)
+            subtype = cast_type.__args__[0] if hasattr(cast_type, "__args__") else None
+            return [subtype(item) if subtype is not None else item for item in value]
+
+        return cast_type(value)
+    except (ValueError, TypeError):
         return default