fixed direct output setting in workflow

Author: tclose

pydra/engine/core.py

@@ -34,6 +34,7 @@
 from .helpers import (
     attrs_fields,
     attrs_values,
+    fields_values,
     load_result,
     save,
     record_error,
@@ -680,11 +681,20 @@ def construct(
         constructor = input_values.pop("constructor")
         # Call the user defined constructor to set the outputs
         output_lazy_fields = constructor(**input_values)
-        if output_lazy_fields is None:
+        if output_lazy_fields is None and all(
+            v is attrs.NOTHING for v in fields_values(outputs).values()
+        ):
             raise ValueError(
                 f"Constructor function for {definition} returned None, must a lazy field "
                 "or a tuple of lazy fields"
             )
+        elif unset_outputs := [
+            n for n, v in fields_values(outputs).items() if v is attrs.NOTHING
+        ]:
+            raise ValueError(
+                f"Mandatory outputs {unset_outputs} are not set by the "
+                f"constructor of {workflow!r}"
+            )
         # Check to see whether any mandatory inputs are not set
         for node in workflow.nodes:
             node._definition._check_rules()

pydra/engine/helpers.py

@@ -107,6 +107,11 @@ def list_fields(definition: "type[TaskDef] | TaskDef") -> list["Field"]:
     ]
 
 
+def fields_values(obj, **kwargs) -> dict[str, ty.Any]:
+    """Get the values of an attrs object."""
+    return {f.name: getattr(obj, f.name) for f in list_fields(obj)}
+
+
 def fields_dict(definition: "type[TaskDef] | TaskDef") -> dict[str, "Field"]:
     """Returns the fields of a definition in a dictionary"""
     return {f.name: f for f in list_fields(definition)}

pydra/engine/tests/test_workflow.py

@@ -4482,10 +4482,10 @@ class EvenException(Exception):
     @python.define
     def PassOdds(x):
         if x % 2 == 0:
-            print(f"x={x}, x%2 = {x % 2} (error)\n")
+            print(f"x={x}, running x%2 = {x % 2} (even error)\n")
             raise EvenException("even error")
         else:
-            print(f"x={x}, x%2 = {x % 2}\n")
+            print(f"x={x}, running x%2 = {x % 2}\n")
             return x
 
     @workflow.define
@@ -4507,13 +4507,16 @@ def WorkyPassOdds(x):
     out, err = capfd.readouterr()
     stdout_lines = out.splitlines()
 
+    with open("/Users/tclose/Desktop/pytest-stdout.txt", "w") as f:
+        f.write(out)
+
     tasks_run = 0
     errors_found = 0
 
     for line in stdout_lines:
-        if "x%2" in line:
+        if "running x%2" in line:
             tasks_run += 1
-        if "(error)" in line:
+        if "(even error)" in line:
             errors_found += 1
 
     # There should have been 5 messages of the form "x%2 = XXX" after calling task() the first time