fix validation issues

Author: giancarloromeo

packages/models-library/src/models_library/api_schemas_directorv2/comp_tasks.py

@@ -50,15 +50,15 @@ class ComputationCreate(BaseModel):
         description="contains information about the wallet used to bill the running service",
     )
 
-    @field_validator("product_name", mode="before")
+    @field_validator("product_name")
     @classmethod
     def ensure_product_name_defined_if_computation_starts(cls, v, values):
         if "start_pipeline" in values and values["start_pipeline"] and v is None:
             msg = "product_name must be set if computation shall start!"
             raise ValueError(msg)
         return v
 
-    @field_validator("use_on_demand_clusters", mode="before")
+    @field_validator("use_on_demand_clusters")
     @classmethod
     def ensure_expected_options(cls, v, values):
         if v is True and ("cluster_id" in values and values["cluster_id"] is not None):

packages/models-library/src/models_library/api_schemas_directorv2/services.py

@@ -21,6 +21,7 @@ class NodeRequirements(BaseModel):
         None,
         description="defines the required (maximum) GPU for running the services",
         alias="GPU",
+        validate_default=True
     )
     ram: ByteSize = Field(
         ...,
@@ -31,6 +32,7 @@ class NodeRequirements(BaseModel):
         default=None,
         description="defines the required (maximum) amount of VRAM for running the services",
         alias="VRAM",
+        validate_default=True
     )
 
     @field_validator("vram", "gpu", mode="before")