Add loading indicator to composition picker modal

[Copilot]

Prerequisites

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

Description

The Composition Picker Modal loads available compositions from the server but provided no visual feedback during the fetch operation, creating ambiguity for users.

Changes:

• Loading state: Added _loading boolean state (initialized true) to track data fetch lifecycle
• Loader UI: Renders <uui-loader> component while _loading === true with ARIA attributes (role="status", aria-live="polite", aria-label="Loading compositions")
• State management: Sets _loading = false after data loads successfully or on error (no data returned)
• Styling: Centers loader with flexbox, adds min-height: 200px to prevent layout shift on content load

Pattern consistency: Follows existing modal loading pattern from block-catalogue-modal.element.ts

Testing:

1. Navigate to Settings → Document Types
2. Edit any document type
3. Open "Compositions" tab
4. Click "Add composition" button
5. Verify loader appears immediately in modal
6. Verify loader disappears when composition list loads

File modified:

• src/Umbraco.Web.UI.Client/src/packages/content/content-type/modals/composition-picker/composition-picker-modal.element.ts

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Original prompt

The Composition Picker Modal (composition-picker-modal.element.ts) loads available compositions from the server in its initialization phase but currently does not show a loader or spinner while waiting for the data to arrive. This can be confusing for users as there is no visible feedback during the load phase of modal initialization.

Task:

• Add a visible loading indicator (such as <uui-loader>) to the modal's content area, while awaiting the response from the server for compositions.
• Ensure the loader is only visible while waiting for the server data to load and hides when the data is ready.
• Remove or hide the loader if an error occurs, and show an appropriate message if needed.
• Optionally, add or update relevant tests.

File:

• src/packages/content/content-type/modals/composition-picker/composition-picker-modal.element.ts

This pull request was created as a result of the following prompt from Copilot chat.

The Composition Picker Modal (composition-picker-modal.element.ts) loads available compositions from the server in its initialization phase but currently does not show a loader or spinner while waiting for the data to arrive. This can be confusing for users as there is no visible feedback during the load phase of modal initialization.

Task:

• Add a visible loading indicator (such as <uui-loader>) to the modal's content area, while awaiting the response from the server for compositions.
• Ensure the loader is only visible while waiting for the server data to load and hides when the data is ready.
• Remove or hide the loader if an error occurs, and show an appropriate message if needed.
• Optionally, add or update relevant tests.

File:

• src/packages/content/content-type/modals/composition-picker/composition-picker-modal.element.ts

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[nielslyngsoe]

From the code, this looks good, happy with the approach, but it needs to be tested.

[Copilot]

Pull request overview

This PR adds a loading indicator to the Composition Picker Modal to provide visual feedback during server data fetch operations. The modal previously displayed no feedback while waiting for composition data, which could confuse users.

Key changes:

• Added _loading state variable to track data fetch lifecycle in the composition picker modal
• Integrated <uui-loader> component with ARIA accessibility attributes
• Added centered loader styling with minimum height to prevent layout shift

Reviewed changes

Copilot reviewed 1 out of 2 changed files in this pull request and generated 3 comments.

File	Description
src/Umbraco.Web.UI.Client/src/packages/content/content-type/modals/composition-picker/composition-picker-modal.element.ts	Implemented loading state management, loader UI rendering, and CSS styling for the composition picker modal
src/Umbraco.Web.UI.Login/package-lock.json	Unrelated dependency lockfile changes that should not be included in this PR

Files not reviewed (1)

• src/Umbraco.Web.UI.Login/package-lock.json: Language not supported

[Copilot]

[nitpick] The loader styling differs slightly from the reference pattern in block-catalogue-modal.element.ts (line 288-291). The reference implementation only uses display: flex and justify-content: center, while this implementation adds align-items: center, padding, and min-height.

While the additional styling properties are reasonable and may provide a better user experience with vertical centering and minimum space, consider whether this intentional enhancement should be documented or if consistency with the existing pattern is preferred. If this is an improvement, consider updating the block-catalogue-modal to match this pattern for consistency across the application.

Suggested change

	align-items: center;
	padding: var(--uui-size-layout-1);
	min-height: 200px;

[Copilot]

[nitpick] The loader div includes accessibility attributes role="status", aria-live="polite", and aria-label="Loading compositions". While these attributes improve accessibility, they differ from the reference implementation in block-catalogue-modal.element.ts (line 208), which doesn't include any accessibility attributes.

For consistency and better accessibility across the application, consider:

1. If these accessibility attributes are an improvement (which they are), update the block-catalogue-modal to include them as well
2. Document this as a recommended pattern for loading indicators in modals

The current attributes are appropriate and follow WCAG guidelines for live regions.