fix metadata test error of value fields

The management of metadata fields may be flawed, necessitating an examination of the eq method or the manner in which fields are retrieved. We will open a separate pull request to address this issue.

sdgx/data_models/metadata.py

@@ -45,6 +45,7 @@ class Metadata(BaseModel):
     """
 
     @field_validator("column_list")
+    # @classmethod
     def check_column_list(cls, v) -> Any:
         # check if v has duplicate element
         if len(v) == len(set(v)):
@@ -70,6 +71,7 @@ def check_column_list(cls, v) -> Any:
     discrete_columns: Set[str] = set()
     datetime_columns: Set[str] = set()
     datetime_format: Dict = defaultdict(str)
+    const_values: Dict = defaultdict(str)
 
     # version info
     version: str = "1.0"
@@ -206,6 +208,7 @@ def set(self, key: str, value: Any):
             key in self.model_fields
             and key not in self.tag_fields
             and key not in self.format_fields
+            and key not in self.value_fields
         ):
             raise MetadataInitError(
                 f"Set {key} not in tag_fields, try set it directly as m.{key} = value"
@@ -252,6 +255,9 @@ def add(self, key: str, values: str | Iterable[str]):
             # already in fields that contains dict
             if key in list(self.format_fields):
                 self.get(key).update(values)
+
+            if key in list(self.value_fields):
+                self.get(key).update(values)
 
             # in extend
             if self._extend.get(key, None) is None: