conditional

Conditional Workflow Example

This example demonstrates how to use conditional logic within a workflow using the ThenStepIf builder method.

Overview

The workflow processes an input value and optionally performs operations based on flags provided in the input.

It showcases:

• Conditional Execution: Using ThenStepIf to execute steps only when a condition is met.
• State Management: Storing flags in the workflow context state for use in conditions.
• Default Values: Providing default output values when a step is skipped.

Workflow Structure

1. Setup Step (setup):

   • Input: ConditionalInput (Value, EnableDoubling, EnableFormatting)
   • Action: Extracts EnableDoubling and EnableFormatting flags and stores them in the workflow state (ctx.State). Passes Value to the next step.
   • Output: DoubleInput (Value)

2. Double Step (double) - Conditional:

   • Condition: Checks if enable_doubling is true in state.
   • Action: Multiples the value by 2.
   • Default: If skipped, returns a default object with Value: 0 and Doubled: false.
   • Output: DoubleOutput (Value, Doubled, Message)

3. Format Step (conditional_format) - Conditional:

   • Condition: Checks if the output value from the double step is greater than 10.
   • Action: Formats the result into a string.
   • Output: ConditionalFormatOutput (Value, Formatted, Doubled)

Data Flow

graph TD
    Input[ConditionalInput] --> Setup[Setup Step]
    Setup --> CheckDouble{Enable Doubling?}
    CheckDouble -->|Yes| Double[Double Step]
    CheckDouble -->|No| DefaultDouble[Default Output]
    Double --> CheckFormat{Enable Formatting?}
    DefaultDouble --> CheckFormat
    CheckFormat -->|Yes| Format[Format Step]
    CheckFormat -->|No| End[End]
    Format --> Output[ConditionalFormatOutput]

Loading

Running the Example

1. Start the Server:

   go run main/main.go

2. Trigger the Workflow (With Doubling):

   curl -X POST http://localhost:3000/api/v1/workflows/conditional \
     -H "Content-Type: application/json" \
     -d '{"value": 10, "enable_doubling": true, "enable_formatting": true}'

3. Trigger the Workflow (Without Doubling):

   curl -X POST http://localhost:3000/api/v1/workflows/conditional \
     -H "Content-Type: application/json" \
     -d '{"value": 10, "enable_doubling": false, "enable_formatting": true}'

Key Code Concepts

Conditional Builder

The ThenStepIf method takes the step, a condition function, and a default value.

// Define condition
shouldDouble := func(ctx *gorkflow.StepContext) (bool, error) {
    var enable bool
    ctx.State.Get("enable_doubling", &enable)
    return enable, nil
}

// Add to workflow
builder.ThenStepIf(NewDoubleStep(), shouldDouble, doubleDefault)

Using State

The SetupStep puts data into the context state, which is accessible by condition functions (and other steps).

ctx.State.Set("enable_doubling", input.EnableDoubling)

Checking Previous Step Output

Conditions can also inspect the output of previous steps using ctx.Outputs.

shouldFormat := func(ctx *gorkflow.StepContext) (bool, error) {
    var doubleOut DoubleOutput
    if err := ctx.Outputs.GetOutput("double", &doubleOut); err != nil {
        return false, nil
    }
    return doubleOut.Value > 10, nil
}