Customizing Commands Beyond the Built-ins

Last updated: 7 Oct 2026

The built-in commands cover most charting. When a workflow needs more, you can add fields to a built-in command, show your own content on it, add commands of your own, or write commands from outside Canvas.

Adding fields to a built-in command #

To collect extra information on a built-in command, such as a few more fields on a Plan, add them with the command metadata form. The fields appear with the command in the note, and their values are saved as command metadata.

Showing your own content on a built-in command #

To display extra information with a built-in command, such as a summary or a reference link, attach HTML to it with set_custom_html. The HTML renders alongside the command in the note. The command must still be staged, not committed.

Adding your own command #

To add your own named command, such as a “Wound assessment” command, there are two routes.

A custom command. You declare it in your plugin’s manifest, and it shows HTML you supply in the note. The command itself is read-only, so the work is in deciding what goes into it and when your plugin inserts it:

• From data your plugin already has: build the HTML from the chart or your own records and originate the command, for example from an event handler.
• From a form you build: gather the data in any interface your plugin shows, then originate the command when the information is ready to submit officially.
  • Action buttons open your form in a modal from the note header or footer, or the chart. Good for a short form the clinician fills in once.
  • Note applications add a tab next to the note body. Good for a longer form the clinician works through during the visit.
  • Other applications, in the patient chart, the app drawer, or the patient portal, gather data outside the note, including answers from the patient.

  The form sends its data to a SimpleAPI endpoint in your plugin, which can save it as it comes in, for example in custom data, so the user can come back to an unfinished form. The custom command you originate at the end is the record in the note.

See the CustomCommand reference for manifest setup, print content, and examples.

A questionnaire-based command. Build a questionnaire and use it with the Questionnaire, Review of Systems, Physical Exam, or Structured Assessment command. Canvas provides the form, so clinicians answer it directly in the note.

Writing commands from outside Canvas #

When another system needs to write commands to a chart, such as an intake form, a device, or an internal tool, use CommandAPI. It turns a command into an HTTP endpoint in your plugin: it reads the request body onto the command, validates it, and writes the command to the note. Writing Commands Over HTTP walks through building one, including checking that the caller may write to the note.