Pre-fill Forms from URL Parameters

Launch workflows (also called startup workflows) run when a form loads to fetch data and make it available throughout the form. Use them to pre-fill fields, check permissions, or load context.

What You’ll Build

A customer feedback form that:

• Loads customer details from URL parameter
• Pre-fills customer name and email
• Shows personalized welcome message

Create Launch Workflow

Create a workflow that accepts a parameter and returns data (workspace/workflows/load_customer.py):

from bifrost import workflow, param, ExecutionContext

@workflow(name="load_customer_data", description="Load customer for feedback form")
@param("customer_id", type="string", required=True)
async def load_customer_data(context: ExecutionContext, customer_id: str):
    """Load customer data for pre-filling form."""

    # Fetch customer from database
    customer = await get_customer(context, customer_id)

    return {
        "customer_name": customer.name,
        "customer_email": customer.email,
        "purchase_date": customer.last_purchase_date,
        "product_name": customer.last_product
    }

Note

The workflow returns a dict. All keys become available as context.workflow.* throughout the form.

Configure Form

1. Open form in builder
2. Right panel → Launch Workflow section
3. Select load_customer_data

Allow URL Parameter

To pass customer_id via URL:

1. Add form field: customer_id (hidden text field)
2. Enable Allow as Query Parameter on the field
3. Save form

Now you can use: /execute/form?customer_id=cust-123

Use Workflow Data

Caution

Important: Default values for form fields do NOT support context expressions. To pre-fill fields with dynamic data, pass values via URL query parameters instead.

Display in HTML Content

Show workflow data using HTML Content fields:

<div className="p-4 bg-blue-50 rounded-lg border border-blue-200">
    <h2 className="font-bold text-lg">
        Welcome back, {context.workflow.customer_name}!
    </h2>
    <p className="text-sm text-gray-700">
        We see you purchased {context.workflow.product_name} on{" "}
        {context.workflow.purchase_date}. We'd love to hear your feedback!
    </p>
</div>

Control Field Visibility

Show fields based on workflow data:

// Show VIP feedback field only for premium customers
context.workflow.customer_tier === "premium";

Common Use Cases

Check User Permissions

@workflow(name="check_permissions")
async def check_permissions(context: ExecutionContext):
    """Check if user can access form."""

    return {
        "is_admin": context.is_platform_admin,
        "user_email": context.email,
        "can_approve": await has_permission(context, "approve_requests")
    }

Use in form visibility rules to show admin-only fields.

Load Organization Context

@workflow(name="load_org_context")
async def load_org_context(context: ExecutionContext):
    """Load organization details."""

    org = await get_organization(context, context.org_id)

    return {
        "org_name": org.name,
        "org_plan": org.subscription_plan,
        "org_features": org.enabled_features
    }

Use to display org info or control feature availability.

Pre-fill from External System

@workflow(name="load_ticket_data")
@param("ticket_id", type="string", required=True)
async def load_ticket_data(context: ExecutionContext, ticket_id: str):
    """Load ticket details for follow-up form."""

    ticket = await fetch_ticket_from_psa(context, ticket_id)

    return {
        "ticket_number": ticket.number,
        "customer_name": ticket.customer,
        "issue_description": ticket.description,
        "priority": ticket.priority
    }

Pre-fill form with existing ticket details for follow-up.

Default Parameters

Provide default values when URL params aren’t provided:

1. In form settings → Default Launch Parameters
2. Enter JSON:

{
    "include_history": true,
    "limit": 10
}

These are used when parameters aren’t in the URL.

Testing

Test launch workflow before using in form:

1. Click Play button next to Launch Workflow in form builder
2. Enter test parameters
3. Click Execute
4. View returned data
5. Verify all expected fields are present

Troubleshooting

Form won’t load: Launch workflow has required parameters but no default values or URL params provided. Add defaults or pass via URL.

Data not appearing: Click Info button in form builder to see context.workflow object. Verify workflow returns expected fields.

Workflow fails: Check workflow logs for errors. Verify parameters are correct type and external APIs are accessible.

Parameters not working: Ensure form field with same name exists and has “Allow as Query Parameter” enabled.

Best Practices

1. Keep workflows fast - They block form load. Avoid slow API calls or heavy processing.
2. Return only needed data - Don’t fetch entire objects if you only need a few fields.
3. Handle missing data - Return sensible defaults if external system returns null.
4. Use caching - Cache expensive lookups to speed up repeated form loads.
5. Test independently - Test launch workflow with Play button before using in form.

Example: Complete Survey Form

Launch Workflow

@workflow(name="load_survey_context")
@param("customer_id", type="string", required=True)
async def load_survey_context(context: ExecutionContext, customer_id: str):
    """Load customer context for satisfaction survey."""
    customer = await get_customer(context, customer_id)

    return {
        "customer_name": customer.name,
        "customer_email": customer.email,
        "last_purchase": customer.last_purchase_date,
        "product_name": customer.last_product_name,
        "is_premium": customer.tier == "premium"
    }

HTML Welcome

<div className="p-6 bg-blue-50 rounded-lg border border-blue-200 mb-4">
  <h2 className="font-bold text-xl mb-2">
    Hi {context.workflow.customer_name}! 👋
  </h2>
  <p className="text-gray-700">
    Thank you for purchasing {context.workflow.product_name}.
    We'd love to hear about your experience!
  </p>
</div>

Form Setup

1. Create hidden field customer_id
2. Enable “Allow as Query Parameter”
3. Set Launch Workflow to load_survey_context
4. Add HTML Content field with welcome message (uses context.workflow.*)
5. Add visibility rules to show/hide fields based on context.workflow.is_premium
6. Share link: /execute/form?customer_id=cust-123

Note: To pre-fill name/email fields, pass them as query parameters: ?customer_id=123&name=John&email=john@example.com

Next Steps

• Display Personalized Welcome Messages - Use workflow data in HTML
• Show Fields Based on User Permissions - Control visibility with workflow data
• Cascading Dropdowns - Use workflow data in dropdowns