First version of DefaultDataFilter

src/workflow/engine.py

@@ -1,7 +1,9 @@
+import ast
 from abc import ABC, abstractmethod
 from typing import Any, Generator
 
 from core.Expando import Expando
+from core.utils import UnreferencedNamesVisitor
 from utils.Datahelper import DataHelper
 
 
@@ -88,11 +90,21 @@ class DefaultDataPresenter(DataPresenter):
     
     return Expando(data.to_dict(self.mappings))
 
+
 class DefaultDataFilter(DataFilter):
+  def __init__(self, filter_expression: str):
+    super().__init__()
+    self.filter_expression = filter_expression
+    self._ast_tree = ast.parse(filter_expression, "<user input>", 'eval')
+    self._compiled = compile(self._ast_tree, "<string>", "eval")
+    visitor = UnreferencedNamesVisitor()
+    self._unreferenced_names = visitor.get_names(self._ast_tree)
+  
   """Default data filter that returns True for all data items."""
   
   def filter(self, data: Any) -> bool:
-    return True
+    my_locals = {name: data.get(name) for name in self._unreferenced_names if hasattr(data, name)}
+    return eval(self._compiled, globals(), my_locals)
 
 
 class WorkflowEngine: