diff --git a/src/cpr_sdk/pipeline_general_models.py b/src/cpr_sdk/pipeline_general_models.py
index 195745f..7096e68 100644
--- a/src/cpr_sdk/pipeline_general_models.py
+++ b/src/cpr_sdk/pipeline_general_models.py
@@ -2,7 +2,7 @@
 from enum import Enum
 from typing import Mapping, Any, List, Optional, Sequence, Union
 
-from pydantic import BaseModel, model_validator
+from pydantic import BaseModel, field_validator, model_validator
 
 Json = dict[str, Any]
 
@@ -54,6 +54,21 @@ def convert_publication_ts_to_date(self):
 
         return self
 
+    @field_validator("type", mode="before")
+    @classmethod
+    def none_to_empty_string(cls, value):
+        """If the value is None, will convert to an empty string"""
+        return "" if value is None else value
+
+    def to_json(self) -> Mapping[str, Any]:
+        """Provide a serialisable version of the model"""
+
+        json_dict = self.model_dump()
+        json_dict["publication_ts"] = (
+            self.publication_ts.isoformat() if self.publication_ts is not None else None
+        )
+        return json_dict
+
 
 class InputData(BaseModel):
     """Expected input data containing RDS state."""
diff --git a/src/cpr_sdk/version.py b/src/cpr_sdk/version.py
index 850f722..19cdcb8 100644
--- a/src/cpr_sdk/version.py
+++ b/src/cpr_sdk/version.py
@@ -1,5 +1,5 @@
 _MAJOR = "1"
-_MINOR = "1"
+_MINOR = "2"
 _PATCH = "10"
 _SUFFIX = ""