Fix issues with with_param

examples/workflows/experimental/script-annotations-dynamic-fanout.yaml

@@ -0,0 +1,60 @@
+apiVersion: argoproj.io/v1alpha1
+kind: Workflow
+metadata:
+  generateName: dynamic-fanout-
+spec:
+  entrypoint: d
+  templates:
+  - dag:
+      tasks:
+      - name: generate
+        template: generate
+      - arguments:
+          parameters:
+          - description: this is some value
+            name: some-value
+            value: '{{item}}'
+        depends: generate
+        name: consume
+        template: consume
+        withParam: '{{tasks.generate.outputs.parameters.some-values}}'
+    name: d
+  - name: generate
+    outputs:
+      parameters:
+      - name: some-values
+        valueFrom:
+          path: /tmp/hera-outputs/parameters/some-values
+    script:
+      args:
+      - -m
+      - hera.workflows.runner
+      - -e
+      - examples.workflows.experimental.script_annotations_dynamic_fanout:generate
+      command:
+      - python
+      env:
+      - name: hera__script_annotations
+        value: ''
+      - name: hera__outputs_directory
+        value: /tmp/hera-outputs
+      image: python:3.9
+      source: '{{inputs.parameters}}'
+  - inputs:
+      parameters:
+      - description: this is some value
+        name: some-value
+    name: consume
+    script:
+      args:
+      - -m
+      - hera.workflows.runner
+      - -e
+      - examples.workflows.experimental.script_annotations_dynamic_fanout:consume
+      command:
+      - python
+      env:
+      - name: hera__script_annotations
+        value: ''
+      image: python:3.9
+      source: '{{inputs.parameters}}'

examples/workflows/experimental/script-runner-io-dynamic-fanout.yaml

@@ -0,0 +1,64 @@
+apiVersion: argoproj.io/v1alpha1
+kind: Workflow
+metadata:
+  generateName: dynamic-fanout-
+spec:
+  entrypoint: d
+  templates:
+  - dag:
+      tasks:
+      - name: generate
+        template: generate
+      - arguments:
+          parameters:
+          - description: this is some value
+            name: some-value
+            value: '{{item}}'
+        depends: generate
+        name: consume
+        template: consume
+        withParam: '{{tasks.generate.outputs.parameters.some-values}}'
+    name: d
+  - name: generate
+    outputs:
+      parameters:
+      - name: some-values
+        valueFrom:
+          path: /tmp/hera-outputs/parameters/some-values
+    script:
+      args:
+      - -m
+      - hera.workflows.runner
+      - -e
+      - examples.workflows.experimental.script_runner_io_dynamic_fanout:generate
+      command:
+      - python
+      env:
+      - name: hera__script_annotations
+        value: ''
+      - name: hera__outputs_directory
+        value: /tmp/hera-outputs
+      - name: hera__script_pydantic_io
+        value: ''
+      image: python:3.9
+      source: '{{inputs.parameters}}'
+  - inputs:
+      parameters:
+      - description: this is some value
+        name: some-value
+    name: consume
+    script:
+      args:
+      - -m
+      - hera.workflows.runner
+      - -e
+      - examples.workflows.experimental.script_runner_io_dynamic_fanout:consume
+      command:
+      - python
+      env:
+      - name: hera__script_annotations
+        value: ''
+      - name: hera__script_pydantic_io
+        value: ''
+      image: python:3.9
+      source: '{{inputs.parameters}}'

examples/workflows/experimental/script_annotations_dynamic_fanout.py

@@ -0,0 +1,30 @@
+"""
+This example showcases how clients can use Hera to dynamically generate tasks that process outputs from one task in
+parallel. This is useful for batch jobs and instances where clients do not know ahead of time how many tasks/entities
+they may need to process.
+"""
+
+from typing import Annotated, List
+
+from hera.shared import global_config
+from hera.workflows import DAG, Parameter, Workflow, script
+
+global_config.experimental_features["script_annotations"] = True
+
+
+@script(constructor="runner")
+def generate() -> Annotated[List[int], Parameter(name="some-values")]:
+    return [i for i in range(10)]
+
+
+@script(constructor="runner")
+def consume(some_value: Annotated[int, Parameter(name="some-value", description="this is some value")]):
+    print("Received value: {value}!".format(value=some_value))
+
+
+# assumes you used `hera.set_global_token` and `hera.set_global_host` so that the workflow can be submitted
+with Workflow(generate_name="dynamic-fanout-", entrypoint="d") as w:
+    with DAG(name="d"):
+        g = generate(arguments={})
+        c = consume(with_param=g.get_parameter("some-values"))
+        g >> c

examples/workflows/experimental/script_runner_io_dynamic_fanout.py

@@ -0,0 +1,38 @@
+"""
+This example showcases how clients can use Hera to dynamically generate tasks that process outputs from one task in
+parallel. This is useful for batch jobs and instances where clients do not know ahead of time how many tasks/entities
+they may need to process.
+"""
+
+from typing import Annotated, List
+
+from hera.shared import global_config
+from hera.workflows import DAG, Input, Output, Parameter, Workflow, script
+
+global_config.experimental_features["script_pydantic_io"] = True
+
+
+class GenerateOutput(Output):
+    some_values: Annotated[List[int], Parameter(name="some-values")]
+
+
+class ConsumeInput(Input):
+    some_value: Annotated[int, Parameter(name="some-value", description="this is some value")]
+
+
+@script(constructor="runner")
+def generate() -> GenerateOutput:
+    return GenerateOutput(some_values=[i for i in range(10)])
+
+
+@script(constructor="runner")
+def consume(input: ConsumeInput) -> None:
+    print("Received value: {value}!".format(value=input.some_value))
+
+
+# assumes you used `hera.set_global_token` and `hera.set_global_host` so that the workflow can be submitted
+with Workflow(generate_name="dynamic-fanout-", entrypoint="d") as w:
+    with DAG(name="d"):
+        g = generate(arguments={})
+        c = consume(with_param=g.get_parameter("some-values"))
+        g >> c

src/hera/shared/_type_util.py

@@ -82,6 +82,24 @@
     return metadata[0]
 
 
+def construct_io_from_annotation(python_name: str, annotation: Any) -> Union[Parameter, Artifact]:
+    """Constructs a Parameter or Artifact object based on annotations.
+
+    If a field has a Parameter or Artifact annotation, a copy will be returned, with missing
+    fields filled out based on other metadata. Otherwise, a Parameter object will be constructed.
+
+    For a function parameter, python_name should be the parameter name.
+    For a Pydantic Input or Output class, python_name should be the field name.
+    """
+    if annotation := get_workflow_annotation(annotation):
+        # Copy so as to not modify the fields themselves
+        annotation_copy = annotation.copy()
+        annotation_copy.name = annotation.name or python_name
+        return annotation_copy
+    else:
+        return Parameter(name=python_name)
+
+
 def get_unsubscripted_type(t: Any) -> Any:
     """Return the origin of t, if subscripted, or t itself.
 

src/hera/workflows/_meta_mixins.py

@@ -25,7 +25,7 @@
 from hera.shared import BaseMixin, global_config
 from hera.shared._global_config import _DECORATOR_SYNTAX_FLAG, _flag_enabled
 from hera.shared._pydantic import BaseModel, get_fields, root_validator
-from hera.shared._type_util import get_annotated_metadata
+from hera.shared._type_util import construct_io_from_annotation, get_annotated_metadata, unwrap_annotation
 from hera.workflows._context import _context
 from hera.workflows.exceptions import InvalidTemplateCall
 from hera.workflows.io.v1 import (
@@ -263,6 +263,17 @@
         return output
 
 
+def _get_pydantic_input_type(source: Callable) -> Union[None, Type[InputV1], Type[InputV2]]:
+    function_parameters = inspect.signature(source).parameters
+    if len(function_parameters) != 1:
+        return None
+    parameter = next(iter(function_parameters.values()))
+    parameter_type = unwrap_annotation(parameter.annotation)
+    if not isinstance(parameter_type, type) or not issubclass(parameter_type, (InputV1, InputV2)):
+        return None
+    return parameter_type
+
+
 def _get_param_items_from_source(source: Callable) -> List[Parameter]:
     """Returns a list (possibly empty) of `Parameter` from the specified `source`.
 
@@ -275,17 +286,24 @@
     List[Parameter]
         A list of identified parameters (possibly empty).
     """
-    source_signature: List[str] = []
-    for p in inspect.signature(source).parameters.values():
-        if p.default == inspect.Parameter.empty and p.kind == inspect.Parameter.POSITIONAL_OR_KEYWORD:
-            # only add positional or keyword arguments that are not set to a default value
-            # as the default value ones are captured by the automatically generated `Parameter` fields for positional
-            # kwargs. Otherwise, we assume that the user sets the value of the parameter via the `with_param` field
-            source_signature.append(p.name)
-
-    if len(source_signature) == 1:
-        return [Parameter(name=n, value="{{item}}") for n in source_signature]
-    return [Parameter(name=n, value=f"{{{{item.{n}}}}}") for n in source_signature]
+    non_default_parameters: List[Parameter] = []
+    if pydantic_input := _get_pydantic_input_type(source):
+        for parameter in pydantic_input._get_parameters():
+            if parameter.default is None:
+                non_default_parameters.append(parameter)
+    else:
+        for p in inspect.signature(source).parameters.values():
+            if p.default == inspect.Parameter.empty and p.kind == inspect.Parameter.POSITIONAL_OR_KEYWORD:
+                # only add positional or keyword arguments that are not set to a default value
+                # as the default value ones are captured by the automatically generated `Parameter` fields for positional
+                # kwargs. Otherwise, we assume that the user sets the value of the parameter via the `with_param` field
+                io = construct_io_from_annotation(p.name, p.annotation)
+                if isinstance(io, Parameter) and io.default is None and not io.output:
+                    non_default_parameters.append(io)
+
+    for param in non_default_parameters:
+        param.value = "{{" + ("item" if len(non_default_parameters) == 1 else f"item.{param.name}") + "}}"
+    return non_default_parameters
 
 
 def _get_params_from_items(with_items: List[Any]) -> Optional[List[Parameter]]:

src/hera/workflows/_mixins.py

@@ -17,7 +17,7 @@
 
 from hera.shared import BaseMixin, global_config
 from hera.shared._pydantic import PrivateAttr, get_field_annotations, get_fields, root_validator, validator
-from hera.shared._type_util import get_workflow_annotation
+from hera.shared._type_util import construct_io_from_annotation
 from hera.shared.serialization import serialize
 from hera.workflows._context import SubNodeMixin, _context
 from hera.workflows._meta_mixins import CallableTemplateMixin, HeraBuildObj, HookMixin
@@ -738,14 +738,9 @@
                     result_templated_str = f"{{{{{subnode_type}.{subnode_name}.outputs.result}}}}"
                     return result_templated_str
 
-                if param_or_artifact := get_workflow_annotation(annotations[name]):
-                    output_name = param_or_artifact.name or name
-                    if isinstance(param_or_artifact, Parameter):
-                        return "{{" + f"{subnode_type}.{subnode_name}.outputs.parameters.{output_name}" + "}}"
-                    else:
-                        return "{{" + f"{subnode_type}.{subnode_name}.outputs.artifacts.{output_name}" + "}}"
-
-                return "{{" + f"{subnode_type}.{subnode_name}.outputs.parameters.{name}" + "}}"
+                param_or_artifact = construct_io_from_annotation(name, annotations[name])
+                output_type = "parameters" if isinstance(param_or_artifact, Parameter) else "artifacts"
+                return "{{" + f"{subnode_type}.{subnode_name}.outputs.{output_type}.{param_or_artifact.name}" + "}}"
 
         return super().__getattribute__(name)
 

src/hera/workflows/io/_io_mixins.py

@@ -11,7 +11,7 @@
 from hera.shared import global_config
 from hera.shared._global_config import _SUPPRESS_PARAMETER_DEFAULT_ERROR_FLAG
 from hera.shared._pydantic import _PYDANTIC_VERSION, FieldInfo, get_field_annotations, get_fields
-from hera.shared._type_util import get_workflow_annotation
+from hera.shared._type_util import construct_io_from_annotation, get_workflow_annotation
 from hera.shared.serialization import MISSING, serialize
 from hera.workflows._context import _context
 from hera.workflows.artifact import Artifact
@@ -45,18 +45,12 @@
 def _construct_io_from_fields(cls: Type[BaseModel]) -> Iterator[Tuple[str, FieldInfo, Union[Parameter, Artifact]]]:
     """Constructs a Parameter or Artifact object for all Pydantic fields based on their annotations.
 
-    If a field has a Parameter or Artifact annotation, a copy will be returned, with name added if missing.
-    Otherwise, a Parameter object will be constructed.
+    If a field has a Parameter or Artifact annotation, a copy will be returned, with missing
+    fields filled out based on other metadata. Otherwise, a Parameter object will be constructed.
     """
     annotations = get_field_annotations(cls)
     for field, field_info in get_fields(cls).items():
-        if annotation := get_workflow_annotation(annotations[field]):
-            # Copy so as to not modify the fields themselves
-            annotation_copy = annotation.copy()
-            annotation_copy.name = annotation.name or field
-            yield field, field_info, annotation_copy
-        else:
-            yield field, field_info, Parameter(name=field)
+        yield field, field_info, construct_io_from_annotation(field, annotations[field])
 
 
 class InputMixin(BaseModel):