Conditional Logic

FlowForm supports dynamic form behavior through server-evaluated conditional rules. Fields can be shown, hidden, or made required based on the values of other fields.

How it works

Each field can have zero or more conditions attached. A condition consists of:

Property	Description
depends_on_field_code	The field whose value triggers this condition
operator	The comparison to perform
value	The value to compare against
action	What happens when the condition is met: show, hide, or require

Conditions are evaluated by the server's ConditionEvaluator service. The client never evaluates conditions locally — it sends the current submission values to the server and receives back the resolved field states.

Supported operators

Operator	Description	Example
equals	Exact match	country equals "US"
not_equals	Does not match	status not_equals "blocked"
contains	Substring match	email contains "@company.com"
greater_than	Numeric greater than	age greater_than "18"
less_than	Numeric less than	score less_than "100"
in	Value is in a comma-separated list	country in "US,CA,UK"
not_in	Value is not in a list	status not_in "blocked,suspended"
empty	Field has no value	company empty
not_empty	Field has a value	email not_empty

Actions

• show — The field becomes visible only when the condition is met. If no show condition is met, the field is hidden.
• hide — The field is hidden when the condition is met. Multiple hide conditions on the same field are OR'd — if any is met, the field hides.
• require — The field becomes required when the condition is met. This only applies when the field is visible.

Evaluating conditions via API

After creating a submission and persisting values, fetch the current field states:

GET /api/v1/submissions/{uuid}/conditions

Response:

{
  "data": [
    { "field_id": 1, "field_code": "email", "is_visible": true, "is_required": true },
    { "field_id": 2, "field_code": "company_name", "is_visible": false, "is_required": false },
    { "field_id": 3, "field_code": "vat_number", "is_visible": true, "is_required": true }
  ]
}

Examples

Example 1: Show a field based on a dropdown

Create a condition on the "Company Name" field:

• depends_on_field_code: employment_status
• operator: equals
• value: employed
• action: show

The "Company Name" field is hidden by default and only appears when the user selects "Employed" in the employment status dropdown.

Example 2: Require VAT for EU countries

Create a condition on the "VAT Number" field:

• depends_on_field_code: country
• operator: in
• value: DE,FR,NL,BE,IT,ES,AT,PT,IE,LU
• action: require

The VAT field is always visible but only becomes required when the selected country is in the EU list.

Example 3: Hide a field when another is empty

Create a condition on the "Manager Email" field:

• depends_on_field_code: has_manager
• operator: equals
• value: 1
• action: show

The manager email field only appears when the "Do you have a manager?" checkbox is checked.

Multiple conditions

A field can have multiple conditions. The evaluation rules:

• Multiple hide conditions: If any hide condition is met, the field is hidden (OR logic).
• show conditions: If a show condition exists, the field is only visible when at least one show condition is met.
• require conditions: Only evaluated when the field is visible. If any require condition is met, the field becomes required.

Starter kit integration

All starter kits (React, Vue, Livewire) automatically fetch conditions after every step change and value persist. Hidden fields are not rendered. Required state overrides the schema default.

The flow:

1. User changes a field value
2. Values are persisted to the server
3. Client calls GET /submissions/{uuid}/conditions
4. Each field's is_visible and is_required state is updated
5. The UI re-renders based on the new states