How to Make PDF Form Fields Required After Selecting a Radio Button
Question details
The user needs to dynamically change specific PDF form fields (day, month, and year) to become mandatory and editable when a 'due date' radio button is selected.
- Product
- Adobe Acrobat
- Device & OS
- not provided
- Scenario
- Creating an interactive PDF form where text fields must respond to conditional logic triggered by a radio button group.
- Observed behavior
- By default, the date fields do not automatically change their required or read-only states when interacting with the radio buttons.
Ensure you have a PDF editor that supports JavaScript scripting for form elements, such as Adobe Acrobat Pro, and that your form already contains the corresponding radio buttons and text fields.
Use JavaScript in Radio Button Actions
Apply custom JavaScript to the radio button's 'Mouse Up' action to dynamically update the required and readonly properties of your target text fields.
You can control field properties dynamically in Acrobat using the `this.getField()` method. By attaching a small snippet of JavaScript to the radio button, you tell the form to update specific fields as soon as the user clicks that option.
Open your PDF document in Adobe Acrobat, navigate to the Tools menu, and select 'Prepare Form'.
Right-click the specific radio button (e.g., the 'due date' option) that should make the fields required, and select 'Properties' from the context menu.
Go to the 'Actions' tab. Select 'Mouse Up' as the Select Trigger, choose 'Run a JavaScript' from the Select Action dropdown menu, and click the 'Add' button.
In the JavaScript Editor, enter the code to make the fields required and editable. For example: `this.getField("Tag").required = true; this.getField("Tag").readonly = false;` Repeat these two lines for your month and year fields, replacing "Tag" with the exact names of those fields. Click OK.
Right-click the alternative radio button (e.g., 'current date') and repeat the process. In its JavaScript editor, use the opposite logic to revert the fields: `this.getField("Tag").required = false; this.getField("Tag").readonly = true;`
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Frequently Asked Questions
How do I test if my JavaScript form fields are working in Acrobat?
To test the functionality, exit the 'Prepare Form' mode by clicking 'Preview' or 'Close' at the top right. Click the radio buttons to verify that the target date fields correctly change their read-only status and show the required field outline.
Can I hide a PDF form field entirely instead of making it read-only?
Yes. Instead of using `.readonly`, you can use `this.getField("FieldName").display = display.hidden;` to hide the field. To reveal it when the radio button is selected, set it to `display.visible` in the target radio button's script.
Why isn't my JavaScript code triggering when I click the radio button?
This usually happens for three reasons: the script is attached to the wrong action trigger (ensure it is set to 'Mouse Up'), the field names in the script do not perfectly match the actual form field names (check for capitalization and spaces), or JavaScript is disabled in your Acrobat Preferences.
