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Basic Fanout

This examples shows some basic hard-coded fan-outs.

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from hera.shared.serialization import serialize
from hera.workflows import Steps, Workflow, script


@script()
def print_message(message):
    print(message)


with Workflow(generate_name="loops-", entrypoint="loop-example") as w:
    with Steps(name="loop-example"):
        # We can pass a list of values to `with_items`
        print_message(
            name="print-message-loop-with-items-list",
            arguments={"message": "{{item}}"},
            with_items=["hello world", "goodbye world"],
        )

        # Or we can skip the arguments kwarg and string templating
        # syntax by passing a list of dictionaries
        print_message(
            name="print-message-loop-with-items-dict",
            with_items=[
                {"message": "hello world"},
                {"message": "goodbye world"},
            ],
        )

        # We can still pass a list of dict values to `with_items`, but must
        # serialize them using Hera's `serialize` function
        print_message(
            name="print-message-loop-with-items-list-of-dicts",
            arguments={"message": "{{item}}"},
            with_items=[
                serialize(item)
                for item in [
                    {"my-key": "hello world"},
                    {"my-other-key": "goodbye world"},
                ]
            ],
        )

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apiVersion: argoproj.io/v1alpha1
kind: Workflow
metadata:
  generateName: loops-
spec:
  entrypoint: loop-example
  templates:
  - name: loop-example
    steps:
    - - name: print-message-loop-with-items-list
        template: print-message
        withItems:
        - hello world
        - goodbye world
        arguments:
          parameters:
          - name: message
            value: '{{item}}'
    - - name: print-message-loop-with-items-dict
        template: print-message
        withItems:
        - message: hello world
        - message: goodbye world
        arguments:
          parameters:
          - name: message
            value: '{{item}}'
    - - name: print-message-loop-with-items-list-of-dicts
        template: print-message
        withItems:
        - '{"my-key": "hello world"}'
        - '{"my-other-key": "goodbye world"}'
        arguments:
          parameters:
          - name: message
            value: '{{item}}'
  - name: print-message
    inputs:
      parameters:
      - name: message
    script:
      image: python:3.10
      source: |-
        import os
        import sys
        sys.path.append(os.getcwd())
        import json
        try: message = json.loads(r'''{{inputs.parameters.message}}''')
        except: message = r'''{{inputs.parameters.message}}'''

        print(message)
      command:
      - python

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