Logic rules

What you need to know

• A rule changes one question, its target, based on answers to questions that come before it.
• There are four actions: show, hide, require and skip.
• A rule only runs after its source question has been answered. Questions the respondent never saw count as unanswered.
• A question that has a show rule stays hidden until one of its show rules matches.
• Conditions compare option IDs for choice questions, never their labels.
• Logic is available on every plan.

Rule format

Rules live in the definition's rules list:

Most rules check the source question itself, so sourceId and each condition's fieldId are the same. They differ when a rule waits for one question and then also checks earlier answers, such as "after the budget question, if the budget is over 5000 and the project type is Website".

A form can have up to 300 rules.

What each action does

• show: the target appears only when the rule matches.
• hide: the target is hidden when the rule matches.
• require: the target becomes required when the rule matches. No rule makes a shown question optional, so for "required only when…" leave required false and add a require rule.
• skip: after the respondent answers the source question, the form jumps to the target and skips every question in between. It only jumps forward. To end a form early, hide the remaining questions instead.

A require rule cannot target a statement, because statements collect no answer.

How rules run

trulyform goes through the questions in order:

1. For each question, it checks the show and hide rules that target it, in the order they appear in rules. The first one that matches decides whether the question is shown or hidden.
2. If none match, the question is hidden when at least one show rule targets it, and shown otherwise.
3. A shown question is required when its required is true or a require rule targeting it matches.
4. After a question is answered, the first matching skip rule whose source is that question jumps forward.

A rule never matches while its source question has no answer, whatever its conditions, so it cannot react to the source being left blank. Once the source has an answer, a condition on a question that is unanswered, hidden or skipped sees no answer: only is_empty matches it.

A hidden or skipped question is never required, even when its required is true. A follow-up shown by a show rule can therefore be required: true: it is enforced only when it appears.

Rules always run on the current answers. When a respondent goes back and changes an answer, the questions that are shown, hidden and required change with it.

Conditions

Comparison values by question type:

• Text comparisons ignore letter case and the spaces around the answer. Website answers compare the saved address exactly, such as "https://example.com".
• Choice values are option IDs. For any_of, the value is a list of option IDs.
• NPS and opinion scale questions with a comment box compare the score.
• A ranking answer always contains every option, so contains on a ranking is always true.

Tips

• Ask a follow-up only when it applies: show the follow-up when the earlier answer matches. Use skip instead to jump past several questions at once.
• "Other, please specify": add an Other option, then a short text question right after it with a show rule on that option.
• Different text for different people: a form has one ending, so pipe answers into it, or add a statement just before the end and show it only to some respondents.
• Several triggers for one question: use mode: "any" with several conditions, or add several show rules.

Example

The workshop registration asks which ticket the person wants and uses that answer three times:

[
    {
        "id": "01990000-0000-7000-8000-000000000121",
        "sourceId": "01990000-0000-7000-8000-000000000103",
        "targetId": "01990000-0000-7000-8000-000000000105",
        "mode": "all",
        "action": "hide",
        "conditions": [{"fieldId":"01990000-0000-7000-8000-000000000103","operator":"eq","value":"01990000-0000-7000-8000-000000000112"}]
    },
    {
        "id": "01990000-0000-7000-8000-000000000122",
        "sourceId": "01990000-0000-7000-8000-000000000103",
        "targetId": "01990000-0000-7000-8000-000000000106",
        "mode": "all",
        "action": "show",
        "conditions": [{"fieldId":"01990000-0000-7000-8000-000000000103","operator":"eq","value":"01990000-0000-7000-8000-000000000111"}]
    },
    {
        "id": "01990000-0000-7000-8000-000000000123",
        "sourceId": "01990000-0000-7000-8000-000000000103",
        "targetId": "01990000-0000-7000-8000-000000000107",
        "mode": "all",
        "action": "require",
        "conditions": [{"fieldId":"01990000-0000-7000-8000-000000000103","operator":"eq","value":"01990000-0000-7000-8000-000000000111"}]
    }
]

1. The first rule hides the session date question for online tickets.
2. The second shows the dietary needs question only for in-person tickets.
3. The third makes the phone number required for in-person tickets.

The job application uses a skip rule: people who have never worked on a remote team jump past the follow-up question about it.