Forms: conditional logic

Introduction

Conditional logic is used on forms and decision tools to:

• progressively show questions or information

• show different questions or information based on previous responses.

Pre-reading

This guide assumes you’re familiar with how to create a Drupal webform.

See our other articles on forms and privacy.

Process

What you need to know

As for all Drupal forms, you need to create the form and embed it in a Landing page in the CMS. Then you publish or preview that Landing page for testing. (Although there is a test function in Drupal forms, it’s more reliable to test on an SDP front end view.)

Applying and testing conditional logic on forms can take a fair bit of trial and error. You’ll do a lot of refreshing of your published/preview page while setting up and testing logic configuration.

Tip: It helps to have 2 browser windows open side by side - building the form in one and testing the preview in the other. Each time you make a change on the form’s logic, you hit refresh on the other screen to see if your change did what you expected or wanted it to do.

What you need to do

Follow this basic process:

1. Plan your logic first (see below).

2. Add all your questions and information in your form in the CMS.

3. Progressively apply conditions and keep testing.

   • Hidden/visible logic can be applied on text fields (not just on 'questions').

   • Specific logic is mainly used with radio and checkbox elements (e.g. Q2 is visible if the response to Q1 is 'no').

Tip: build screen

When you are in the Build mode on a webform, you can see if conditional logic has been applied to a question or piece of text by looking in the ‘Conditional’ column. Click Edit to add logic.

Open

How to use conditional logic settings

When you’re in Edit mode of a form element (a question or piece of text), you’ll see a panel on the right of your screen. Click the ‘Conditions’ tab to apply settings.

Open

In this example, we can see that question 4 (at the top in black) is set to be visible if the answer to question 3 is ‘Individual’. You can infer that there will be another question set up if the answer to question 3 is something else.

From the screenshot above:

1 = State: Visible or Hidden (usually 'visible')

2 = All, Any or One (to add more than 1 element so that ‘all’ or ‘any’ are applicable, click the plus icon next to the element)

3 = Options include: Empty / Filled; Checked / Unchecked; Value is /Value is not

Plan your logic

People often set up a flowchart to map out the logic of a form or tool. I find it helpful to transfer this info a document to plan the numbering and the logic. Here’s an example:

Email handlers can have logic too

Refer to Create a Drupal webform - email notifications.

To add an email handler, go to Settings > Emails / Handlers.

On this example from the Email handers screen, you’ll see:

• on the left are free-text notes on the conditons

• in the middle is a summary of the settings, notably the ‘reply to’ address and the custom subject line

• on the right you can see that conditions (logic) have been set

This was a complex setup with many different email addresses and logic that included specific responses to 3 questions.

The State for email handlers is either Enabled or Disabled. The conditions required that all 3 elements needed to have the set value in order for the handler to take the specified action (i.e. send to the specified email address).

Disable submissions

On the Settings tab of the form there’s a checkbox to disable submissions. This stops submissions being stored in the Drupal CMS. Submissions will only get emailed to the inbox specified.

Submissions rely on the Submit button being visible (the default setting on all new forms).

Hide the submit button

If you’re building a decision tool and don’t want the user to submit their responses you should hide the submit button.

To remove the default Submit button, click on Edit and tick the Hide submit button checkbox.