🐛 fix(flow.py): change flow field type from str to Dict to allow for JSON data

✨ feat(flow.py): add validator to ensure flow field is a valid JSON object with required fields
The flow field in the FlowBase model has been changed from a string to a dictionary to allow for JSON data. A validator has been added to ensure that the flow field is a valid JSON object with the required fields. The tests have been updated to reflect these changes.

src/backend/langflow/database/models/flow.py

@@ -1,6 +1,7 @@
-from sqlmodel import Field, SQLModel, Relationship
+from pydantic import validator
+from sqlmodel import Field, SQLModel, Relationship, JSON, Column
 from uuid import UUID, uuid4
-from typing import TYPE_CHECKING
+from typing import TYPE_CHECKING, Dict
 
 if TYPE_CHECKING:
     from langflow.database.models.flowstyle import FlowStyle
@@ -8,9 +9,36 @@ if TYPE_CHECKING:
 
 class FlowBase(SQLModel):
     name: str = Field(index=True)
-    flow: str = Field(index=False)
+    flow: Dict = Field(default_factory=dict, sa_column=Column(JSON))
     style: "FlowStyle" = Relationship(back_populates="flow")
 
+    @validator("flow")
+    def validate_json(v):
+        # dict_keys(['description', 'name', 'id', 'data'])
+        if not isinstance(v, dict):
+            raise ValueError("Flow must be a valid JSON")
+        if "description" not in v.keys():
+            raise ValueError("Flow must have a description")
+        if "data" not in v.keys():
+            raise ValueError("Flow must have data")
+
+        # data must contain nodes and edges
+        if "nodes" not in v["data"].keys():
+            raise ValueError("Flow must have nodes")
+        if "edges" not in v["data"].keys():
+            raise ValueError("Flow must have edges")
+
+        return v
+
+    # @validator("flow")
+    # def flow_must_be_json(cls, v):
+    #     try:
+    #         valid_json = json.loads(v)
+
+    #     except Exception as e:
+    #         raise ValueError(f"Flow must be a valid JSON: {e}") from e
+    #     return v
+
 
 class Flow(FlowBase, table=True):
     id: UUID = Field(default_factory=uuid4, primary_key=True, unique=True)