Watch Tool

Overview

Watch keeps a live table of HL7 paths for the message you have selected, and optionally shows a Liquid HTML preview of that message in a side panel (WebView).

Watch list — Path, Value, and Description update as you change or navigate messages.
WebView — Compact clinical-style HTML (message header, patient, observations) rendered from an HTML Liquid template pack.
Three lists — Switch among Watch 1, Watch 2, and Watch 3 for different path sets.

At a glance
Open from Tools → Watch, or use Ctrl+W / Ctrl+Shift+W / Watch Field
Left: watch-list grid · Right: Liquid HTML WebView (when WebView is on)
Templates on the Watch toolbar manages HTML packs used by the preview
Built-in HTML is read-only — Edit or Clone creates a writable copy
Not the same as Watch Folder (auto-load files from a folder) or the full Templates tool

Opening Watch

Open an HL7 v2 message tab and select a message.
Show Watch from the Tools menu (Show/Hide Tools), or:
- Ctrl+W (with the message editor active) — show Watch
- Ctrl+Shift+W — show Watch and add the currently selected field
- Ribbon Watch Field — add the selected field and show Watch

Watch docks like other tools. HL7Spy remembers your WebView on/off preference and which HTML pack you last used.

Layout

Area	What it shows

Area	What it shows
Watch list (left)	Editable list of HL7 paths with live Value and Description
WebView (right)	Liquid → HTML preview of the selected message (not of the watch-list rows)

Use the WebView toolbar toggle to show or hide the preview panel. When hidden, the watch list uses the full width.

Tip
The HTML preview follows the message selected in your current HL7 message tab. Changing which paths you watch does not change the HTML layout unless you customize the template pack.

Watch lists

Columns

Column	Purpose

Column	Purpose
Path	HL7 path to watch (for example `MSH-9`, `PID-5`, `OBX-5.1`)
Value	Current value for that path in the selected message (read-only in the grid)
Description	Description of the path

You can type a new path in the empty row at the bottom of the grid. Selecting a row syncs the path with the message editor when possible. Press Delete to remove selected rows.

Adding paths

Method	Result

Method	Result
Add on the Watch toolbar	Adds the field currently selected in the HL7 editor
Watch Field / Ctrl+Shift+W	Adds the selection and shows Watch
Editor context menu	Add Segment Fields / Components to Watch List when a segment is selected
Type in the new-item row	Enter a path directly

Watch 1 / 2 / 3

Three independent lists. Switching lists loads that set of paths. Watch 1 is seeded with MSH-9 and PID-5 by default for new users.

Decode and Highlight

Toggle	What it does

Toggle	What it does
Decode	Formats values such as dates/times into a more readable form in the Value column
Highlight	Highlights watched paths in the HL7 message editor

Save, undo, import, export

Action	What it does

Action	What it does
Save (Ctrl+S in Watch)	Persist the current watch list
Undo	Restore the last saved list
File → Import Watch List	Load a `.jspy` watch list
File → Export Watch List	Save the current list as `.jspy`
File → Clear Watch List	Clear all rows in the active list
Drag-and-drop a `.jspy` onto Watch	Import that list

Toolbar reference

Control	What it does

Control	What it does
File	Save, Undo, Import/Export Watch List, Clear
Save	Save the current Watch List settings
Add	Add the currently selected field from the HL7 editor
Undo	Undo the previous operation
Up / Down	Reorder the selected watch item
Decode	Decode HL7 values (for example date/time) in the Value column
Highlight	Highlight Watch List fields in the HL7 editor
Watch 1 / 2 / 3	Switch among three watch lists
Export	Generate a Watch List report to Excel across messages
Report	Generate a Watch List report to various formats
WebView	Show or hide the Liquid HTML preview panel
Templates	Manage HTML Liquid template packs used by Watch
Help	This page

HTML preview (WebView)

When WebView is on, Watch renders the selected message with an HTML Liquid template pack (default: Built-in HTML) and displays the result in a WebView2 panel.

How the preview updates

You select a message (or the selection changes).
Watch activates the current HTML pack (HtmlPackId, falling back to Built-in HTML).
The pack picks a root template: first matching enabled rule, otherwise _default.
Liquid renders HTML; Watch navigates the WebView to that HTML.
Zoom tracks the message editor font size; colors follow the application dark/light theme.

Note
Watch shows only the rendered WebView. Unlike the Templates tool, there is no separate Html source tab in Watch.

Built-in HTML layout

The built-in pack is meant for a quick scan of the selected message. Sample rules vary the preview by message type:

Condition	Preview

Condition	Preview
ADT^A18	Surviving patient (PID / PV1) plus prior / merged patient fields from MRG
ADT^A08	Same patient sections with an alternate “Patient update” stylesheet
Anything else	Default compact clinical layout

Message

Type, Time, Control ID, From, To, Version (from MSH)

Patient (when PID / PV1 are present)

MRN, Name, Sex, DOB, Age (from PID)
Admit (when present), Class, Location, Attending / Referring (when present), Visit # (from PV1)

Observations (when order groups are present)

One block per order group: accession / order fields from OBR, then a table of OBX results (#, ID, Value, Units, Status)
OBX Value uses format_obx_value so most types show the full OBX-5 text; ED shows a short summary plus a truncated data preview; leading empty CE components (for example comment-style ^text…) omit the leading ^

Requirements

Microsoft WebView2 runtime must be available on the machine.
If WebView2 fails to initialize, HL7Spy shows a warning, turns WebView off, and saves that preference.

Managing HTML templates

Click Templates on the Watch toolbar to open Manage Templates. Watch lists HTML packs only (the same store as the Templates tool; FHIR packs are not shown here).

Action	What it does

Action	What it does
Open	Activate the selected pack for Watch’s HTML preview
Edit	Open the template editor. Built-in HTML opens a writable local copy (for example `{username}-html`)
Clone	Create an editable copy of the selected pack under a new name
Import	Import a pack from `.nupkg` or `.zip` (HTML packs only)
Export	Export the selected pack as `.nupkg`
Delete	Delete a writable pack (cannot delete Built-in HTML)

Double-click a pack (or press Enter) to Open it.

Built-in packs are read-only
You cannot save changes into Built-in HTML. Use Edit (local user copy) or Clone, then customize Liquid files and rules.

How a template is chosen

Rules are evaluated top to bottom.
The first enabled rule whose Condition matches the current message wins (for example MSH-9.1 = 'ADT' AND MSH-9.2 = 'A18').
If nothing matches, _default is used.

Other files under templates/ (for example msh, pid, pv1, order-group, styles) are includes — they are never chosen as the root by themselves.

When the editor opens, the pack README.md (if present) is shown first as a Markdown overview.

Customize the Watch HTML preview

In Watch, click Templates.
Select Built-in HTML → Edit or Clone.
Read the pack README in the editor.
Adjust _default, add conditioned Rules, or edit includes (msh, pid, pv1, order-group, and so on).
Save. Watch reloads the pack and refreshes the WebView for the selected message.

Share a pack

Templates → Export and save the .nupkg.
On another machine: Templates → Import and select the file, then Open it in Watch.

Liquid helpers for HTML preview

HTML packs use ordinary Liquid plus HL7Spy filters. Common path filters:

Filter	What it returns	Example

Filter	What it returns	Example
`get_path`	Raw field value	`{{ "MSH-9" \\\| get_path }}`
`format_name`	Name components joined with commas	`{{ "PID-5" \\\| format_name }}`
`format_date_path`	Readable date (optional .NET format)	`{{ "PID-7" \\\| format_date_path }}`
`age`	Whole years from a DOB path	`{{ "PID-7" \\\| age }}`
`describe`	Schema description for a coded value	`{{ "PID-8" \\\| describe }}`
`expression`	Result of an HL7Spy expression	`{{ "Coalesce(OBR-3.1,OBR-2.1)" \\\| expression }}`
`format_obx_value`	OBX-5 display text from an OBX segment (full value; ED summary + optional truncated data preview). Pass a max length for the ED data preview (default 100).	`{{ obx \\\| format_obx_value: 100 }}`

Message structure example (order groups):

{%- for group in hl7v2Data.OrderGroups -%}
  {%- for obr in group.OBRs -%}
    {{ obr.4.Value }}
  {%- endfor -%}
  {%- for obx in group.OBXs -%}
    {{ obx.3.Value }} = {{ obx | format_obx_value: 100 }}
  {%- endfor -%}
{%- endfor -%}

Host functions can also be called with {% fn … %} or | fn: (for example {% fn format_name "PID-5" %}). See the Built-in HTML pack README in the template editor for the full filter and function list.

Reports

Button	What it does

Button	What it does
Report	Build a multi-format report of the fields in the current Watch List across messages
Export	Generate a Watch List report to Excel

These use the watch-list paths, not the HTML WebView layout.

Shortcuts

Shortcut	Action

Shortcut	Action
Ctrl+W	Show Watch (when the message editor is active)
Ctrl+Shift+W	Show Watch and add the currently selected field
Ctrl+S	Save the current watch list (when Watch is active)
Delete	Remove selected watch-list rows
Ctrl+F / Ctrl+G	Search / Goto (same pattern as other tools)
Alt+Left / Alt+Right	Previous / next message

Troubleshooting

Symptom	What to try

Symptom	What to try
WebView panel missing	Turn WebView on in the Watch toolbar.
WebView turned itself off / warning on open	WebView2 failed to initialize. Install or repair the WebView2 runtime, restart HL7Spy, then turn WebView back on.
Blank or unexpected HTML	Confirm a message is selected. Check which pack is active under Templates → Open. For Built-in HTML, try ADT^A08 / ADT^A18 samples vs a default ORU.
Cannot edit Built-in HTML