Conditional logic

A condition shows a field, or a whole section, only when the visitor’s other answers match rules you set. Everything else about the field stays the same; it simply appears and disappears as the visitor fills in the form.

When to use it

• A follow-up question that only applies to one answer: “Other — please specify”.
• A group of questions for one kind of enquiry, in a section that appears when that kind is chosen.
• Conditions change only what is shown. To email different people depending on an answer, see Email notifications.

How to add a condition

Add conditions to the field or section that should appear. It holds a list of rules and how they combine:

{
  "key": "other_detail",
  "type": "text",
  "label": "Please specify",
  "required": true,
  "conditions": {
    "logic": "and",
    "rules": [
      {"field": "service", "operator": "equals", "value": "other"}
    ]
  }
}

• field is the key of the field to check.
• value is compared with the stored value of an option, not its label.
• logic is and (every rule must match, the default) or or (any rule).

The form re-checks the rules as the visitor types and chooses.

Operators

Operator	Shorthand	Matches when the checked field…
equals	==, =	is exactly value
not_equals	!=, <>	is anything but value
contains	—	contains value, ignoring case
not_contains	—	does not contain value, ignoring case
is_empty	empty	has nothing entered or chosen
is_not_empty	not_empty	has something entered or chosen
is_checked	checked	is a single tick box that is ticked
is_not_checked	not_checked	is a single tick box that is not ticked
greater_than	>	is a number larger than value
less_than	<	is a number smaller than value
greater_than_or_equals	>=	is a number at least value
less_than_or_equals	<=	is a number at most value
in	—	is one of the values in a list: "value": ["a", "b"]
not_in	—	is none of the values in a list

An operator the form does not recognise counts as matching.

What happens to a hidden field

• It is not required while hidden. The visitor can submit without it.
• Its value is thrown away on submission, so it does not appear in the entry, the notification email or the webhook, even if the visitor typed something before it was hidden.
• The server checks the rules again on submission; it does not rely on what the browser showed.

Limits and common problems

• Checking a checkbox group. For a group where several boxes can be ticked, use contains (true when any ticked value contains value), is_empty or is_not_empty. equals compares one value and never matches a group. Use radio buttons or a dropdown when a condition needs exactly one chosen value.
• The condition never matches. Check that field is the field’s key, and that value is the option’s value rather than its label.

Note

Up to version 1.10.0: radio buttons, checkboxes and messages with conditions stay visible in the browser; required fields in a hidden section are still required, so the form cannot be submitted; contains on a checkbox group drops the visitor’s answer; and a rule naming a key with a capital letter never matches. All four are fixed in version 1.10.1. On 1.10.0, put conditional radio buttons and checkboxes in a section, repeat a section’s conditions on each required field in it, and use lowercase keys.

Related pages

• Field types — All 13 field types, the properties each one takes, and the options every field shares.
• Layout and steps — Put fields side by side in columns, group them in sections, and split a long form into steps with a progress indicator.
• Validation messages and errors — Every message a visitor can see when a submission is refused, and the errors shown when a form's JSON cannot be saved.