QR Code

A REDCap external module providing an action tag that will generate a QR code when a form is saved.

Installation

Clone this repo into <redcap-root>/modules/redcap_qrcode_<version-number>, or
Obtain this module from the Consortium REDCap Repo via the Control Center.
Go to Control Center > Technical / Developer Tools > External Modules and enable QR Code.

Requirements

REDCAP 10.1.0 or newer (tested on REDCap 12.4.1)

Configuration

There are no module-specific system or project configuration options.
All action is controlled by the .... action tag ;)

Action Tag

@QRCODE="source_field"

Apply this action tag to a fields of type Text Box (no validation) or File Upload only, and specifiy the name of the source field (which needs to be on the same form).

The value of source_field will be converted to a QR code and stored in the field with the action tag. The storage format will depend on the field type:

PNG file stored in edocs when used on a File Upload field
Base64-encoded string when used on a Text Box field. This could then be used to produce inline-images with <img src="data:image/png;base64, [field_with_qrcode]">

Use case

You might want to include a QR code in an email or notification, or to display it on a data entry form or survey. This module will allow you to do this.

Notes & Limitations

This action tag is applied on saving only. Do not expect it to work in real time (i.e. in the browser, with live updates as with piping).
However, the string value, once existing, can be piped freely. Thus, there should virtually no limits in displaying the QR code anywhere (i.e. on different instruments, in ASIs or Alerts & Notifications).
One exception though: there is no way to get a QR code onto the first page of a public survey. No can do. Sorry. Simply use the 'one section per page' option.
Text box fields must not have any validation.
The source_field_name field must be on the same instrument. Specify the field name only, no square brackets (this is not piping).
The QR code will be generated each time (i.e. it will be overwritten if the source value changes; @READONLY is not honored).
When using a file upload field as destination, previous versions will not be kept. Each new version will generate a new file version (if file versioning is on) but automatically delete the previous version. The module is smart enough to not overwrite identical QR codes, though. This is to prevent unnecessary clutter. Also, changes of the source field for the QR code will be logged anyway, so there is no need to have this for derived data.
Note, each QR code generation will create a temporary file, and in case of a file upload field as destination, will copy the previously stored file to the temp folder for inspection. Thus, this module might seriously slow down your server in high throughput situations.
On data entry forms and surveys, the "Upload file" / "Upload new version" links are removed for file upload file upload fields with @QRCODE.

Tips & Tricks

Alerts & Notifications, as well as ASIs, force you to use the Rich Text Editor, which can be a major pain sometimes (read: often). As when you would like to include a barcode. To do so, you have to jump through hoops.
So, normally you would expect to go into source view, and simply enter the image tag shown above. This works. Kinda. But only the first time you save the Alert / ASI, because on load, the Rich Text Editor thinks it is smart (when it is not) and removes the src tag of your image. Nice. Thank you very much.
So, here's how you do it:
- Create a helper text field and use a calctext expression similar to this one:
  @CALCTEXT(concat('<img src="data:image/png;base64, ', [text_qr], '">'))
  where text_qr is your field with @QRCODE.
- Then, pipe the field with the above calctext into the email message. Thankfully, Rich Text Editor will leave it alone then.

How to display, e.g., the Survey Queue Url, on a data entry form - This is a generic example illustrating how to get QR codes displayed on data entry or survey pages.

Create the following fields in a project with the survey queue enabled:

Variable Name	Field Label	Action Tags / Field Annotation
sq_url	Survey Queue Url	`@DEFAULT="[survey-queue-url]" @HIDDEN`
sq_qrcode	QR Cdoe	`@QRCODE="sq_url" @HIDDEN`
sq_display	`<img src="data:image/png;base64, [sq_qrcode]">`	-

Go to the form in data entry mode. Press Save and Stay. The QR code will be displayed on the page.

Changelog

Version	Description
v1.0.3	Added example to README.
v1.0.2	Remove a REDCap v12 dependency.
v1.0.1	Replaced a method call that was no longer available in REDCap.
v1.0.0	Initial release.

kcmcg/redcap-qrcode