diff --git a/src/yeardata/schema.py b/src/yeardata/schema.py
index 71c32f7..ee20353 100644
--- a/src/yeardata/schema.py
+++ b/src/yeardata/schema.py
@@ -2,7 +2,7 @@ from datetime import datetime
 from typing import List, Optional
 from uuid import UUID
 
-from pydantic import Field
+from pydantic import Field, field_validator
 from src.models import DefaultBase, Pagination
 
 
@@ -27,6 +27,25 @@ class YeardataBase(DefaultBase):
     created_by: Optional[str] = Field(None, nullable=True)
     updated_by: Optional[str] = Field(None, nullable=True)
 
+    @field_validator(
+        "asset_crit_ens_energy_not_served",
+        "asset_crit_bpp_system",
+        "asset_crit_bpp_pembangkit",
+        "asset_crit_dmn_daya_mampu_netto",
+        "asset_crit_marginal_cost",
+        "asset_crit_efdh_equivalent_forced_derated_hours",
+        "asset_crit_foh_forced_outage_hours",
+        "asset_crit_extra_fuel_cost",
+        "cf",
+        "eaf",
+        mode="before",
+    )
+    @classmethod
+    def empty_string_to_none(cls, v):
+        if v == "":
+            return None
+        return v
+
 
 class YeardataCreate(YeardataBase):
     pass