refactor(api): add BaseModel conversation variable schemas (#35296)

Co-authored-by: ai-hpc <ai-hpc@users.noreply.github.com>

api/fields/conversation_variable_fields.py

@@ -1,5 +1,13 @@
-from flask_restx import Namespace, fields
+from __future__ import annotations
 
+from datetime import datetime
+from typing import Any
+
+from flask_restx import Namespace, fields
+from graphon.variables.types import SegmentType
+from pydantic import field_validator
+
+from fields.base import ResponseModel
 from libs.helper import TimestampField
 
 from ._value_type_serializer import serialize_value_type
@@ -29,6 +37,74 @@ conversation_variable_infinite_scroll_pagination_fields = {
 }
 
 
+def _to_timestamp(value: datetime | int | None) -> int | None:
+    if isinstance(value, datetime):
+        return int(value.timestamp())
+    return value
+
+
+class ConversationVariableResponse(ResponseModel):
+    id: str
+    name: str
+    value_type: str
+    value: str | None = None
+    description: str | None = None
+    created_at: int | None = None
+    updated_at: int | None = None
+
+    @field_validator("value_type", mode="before")
+    @classmethod
+    def _normalize_value_type(cls, value: Any) -> str:
+        exposed_type = getattr(value, "exposed_type", None)
+        if callable(exposed_type):
+            return str(exposed_type().value)
+        if isinstance(value, str):
+            try:
+                return str(SegmentType(value).exposed_type().value)
+            except ValueError:
+                return value
+        try:
+            return serialize_value_type(value)
+        except (AttributeError, TypeError, ValueError):
+            pass
+
+        try:
+            return serialize_value_type({"value_type": value})
+        except (AttributeError, TypeError, ValueError):
+            value_attr = getattr(value, "value", None)
+            if value_attr is not None:
+                return str(value_attr)
+            return str(value)
+
+    @field_validator("value", mode="before")
+    @classmethod
+    def _normalize_value(cls, value: Any | None) -> str | None:
+        if value is None:
+            return None
+        if isinstance(value, str):
+            return value
+        return str(value)
+
+    @field_validator("created_at", "updated_at", mode="before")
+    @classmethod
+    def _normalize_timestamp(cls, value: datetime | int | None) -> int | None:
+        return _to_timestamp(value)
+
+
+class PaginatedConversationVariableResponse(ResponseModel):
+    page: int
+    limit: int
+    total: int
+    has_more: bool
+    data: list[ConversationVariableResponse]
+
+
+class ConversationVariableInfiniteScrollPaginationResponse(ResponseModel):
+    limit: int
+    has_more: bool
+    data: list[ConversationVariableResponse]
+
+
 def build_conversation_variable_model(api_or_ns: Namespace):
     """Build the conversation variable model for the API or Namespace."""
     return api_or_ns.model("ConversationVariable", conversation_variable_fields)