Templates: Fix "Discard changes?" dialog after creating template with master template (fixes #20262)

[iOvergaard]

Prerequisites

• I have added steps to test this contribution in the description below

Fixes: #20262

Description

This PR fixes a bug where the "Discard changes?" dialog appears after creating and saving a template with a master template, even though no changes were made.

Root Cause

When a template is created with a master template and saved:

1. The workspace auto-redirects from /create/... to /edit/{id}
2. The load() method sets both persisted and current data from the server
3. setMasterTemplate(unique, false) is called to update the UI
4. Bug: The _data.updateCurrent() call was executing even when updateLayoutBlock=false, causing the current data to diverge from persisted data
5. This triggered the spurious "Discard changes?" dialog

The Fix

Moves the _data.updateCurrent({ masterTemplate: unique ? { unique } : null }) call inside the if (updateLayoutBlock) block in the setMasterTemplate() method.

This completes the fix started in PR #20529, which added the updateLayoutBlock parameter to prevent overwriting layout settings from disk, but inadvertently left the data model update outside the conditional.

Before:

if (updateLayoutBlock) {
    this.#updateMasterTemplateLayoutBlock();
}
this._data.updateCurrent({ masterTemplate: unique ? { unique } : null });

After:

if (updateLayoutBlock) {
    this.#updateMasterTemplateLayoutBlock();
    this._data.updateCurrent({ masterTemplate: unique ? { unique } : null });
}

Why This Works

• When updateLayoutBlock=false (during load): We only update the #masterTemplate observable for UI display, without modifying the data model or content
• When updateLayoutBlock=true (during user actions): We update both the layout block in the Razor content AND the data model, properly marking the workspace as having changes

Testing

Test 1: Creating a Template with Master Template (Issue #20262)

1. Create a master template (e.g., "MasterLayout")
2. Create a new template and select "MasterLayout" as the master template
3. Save the template
4. Navigate away from the template
5. ✅ Expected: No "Discard changes?" dialog should appear
6. ❌ Before fix: "Discard changes?" dialog appeared

Test 2: Creating a Sub-Template Under a Parent

1. Create a master template (e.g., "ParentTemplate")
2. Right-click on "ParentTemplate" in the tree and select "Create"
3. Name the new template (e.g., "ChildTemplate") and save
4. Verify the content shows Layout = "ParentTemplate.cshtml";
5. Navigate away from the template
6. ✅ Expected: No "Discard changes?" dialog should appear

Test 3: Changing Master Template via UI Picker

1. Create or open an existing template
2. Click the "Master template" button and select a different master template
3. Verify the layout block in the content is updated (e.g., Layout = "NewMaster.cshtml";)
4. Try to navigate away
5. ✅ Expected: "Discard changes?" dialog SHOULD appear (this is a real unsaved change)
6. Save the template
7. Navigate away
8. ✅ Expected: No "Discard changes?" dialog should appear

Test 4: Removing Master Template via UI

1. Open a template that has a master template set
2. Click the delete icon next to the master template button to remove it
3. Verify the layout block is updated to Layout = null;
4. Try to navigate away
5. ✅ Expected: "Discard changes?" dialog SHOULD appear (this is a real unsaved change)

Test 5: Preserving Layout from Disk (PR #20529 regression check)

1. Create two templates at the root (e.g., "LayoutBase" and "ContentPage")
2. Manually edit the "ContentPage.cshtml" file on disk to set Layout = "LayoutBase.cshtml";
3. Load "ContentPage" in the backoffice
4. ✅ Expected: The backoffice shows Layout = "LayoutBase.cshtml"; (not overwritten to Layout = null;)
5. Navigate away
6. ✅ Expected: No "Discard changes?" dialog should appear

[Copilot]

Pull Request Overview

This PR fixes a bug in the template workspace context where the master template data was being updated unconditionally, even when the updateLayoutBlock parameter was false. The change moves the _data.updateCurrent() call inside the conditional block to only update when layout blocks should be updated.

• Moved the master template data update to only execute when updateLayoutBlock is true

[leekelleher]

Tested out, works as described! 🚀