AutoDefaultSlicer

A native-like Power BI slicer with dynamic default selection.

AutoDefaultSlicer is a Power BI custom visual designed to behave similarly to the native slicer while adding configurable dynamic default selection such as Max, Min, or None.

Power BI's native slicer does not provide a general-purpose dynamic default selection that recalculates automatically when a report is opened. AutoDefaultSlicer solves this without requiring helper measures, "dirty status" tables, or special preselection models: bind a field, choose Default selection = Max, and the slicer opens on the latest year, month, or date every time.

Year                      Month                     Date
┌──────────────────┐      ┌──────────────────┐      ┌──────────────────┐
│ 2026           ▼ │      │ September      ▼ │      │ 10/09/2026     ▼ │
└──────────────────┘      └──────────────────┘      └──────────────────┘

Features

• Dynamic default selection — Max, Min, or None, resolved on the Sort By field when one is bound, otherwise on the value itself.
• Default behavior — On Load recomputes the default every time the report opens, ignoring whatever was selected when it was saved; Only When Empty honours an existing filter and applies the default only when there is none.
• Selection modes — Single, Single or All, Multi.
• Multi display — a compact Dropdown, or a List with click-to-toggle that does not require Ctrl/Cmd and a configurable number of visible rows.
• Sort By field — orders the options and decides Max/Min independently of the displayed text (so "September" beats "August" by month number).
• Select All with a configurable label, and a Clear behavior setting (back to the default, to All, or to nothing).
• Native-like UX — every mode renders a native HTML <select>, so the option list opens over the report instead of being clipped inside the visual.
• Model formatting — text, numbers and dates use the column's format string and the report locale (a Short Date column reads 10/09/2026).
• Real filtering — the visual applies a filter on the bound column through the official Filter API; All removes only the filter this visual created.
• Session-scoped selection — nothing is persisted with persistProperties; a user's choice lasts for their session and the default rule decides again on the next open.
• Localized UI text — English and Spanish resources, with format-pane overrides.
• Power BI Report Server support — tested end-to-end; apiVersion 5.3.0, no APIs newer than the September 2023 Report Server release.
• No helper DAX — no measures, no auxiliary tables, no per-instance flags.

Quick start

1. Download the latest AutoDefaultSlicer.pbiviz from GitHub Releases.
2. Import it into Power BI Desktop: Visualizations → … → Import a visual from a file.
3. Add a field to Value.
4. Optionally add a numeric or date field to Sort By.
5. In the format pane, set Selection → Default selection → Max.
6. Use the visual like a normal slicer.

Three independent instances on one page is the typical setup:

Slicer	Value	Sort By	Default selection	Opens on
Year	Calendar[Year]	—	Max	latest year
Month	Calendar[Month]	Calendar[Month Number]	Max	latest month by number
Date	Calendar[Date]	Calendar[Date ID]	Max	latest date

Each instance keeps its own state and filters its own column; they do not interfere with each other.

Settings

All settings live in the format pane.

Card	Setting	Options	Default
Selection	Selection mode	Single / Multi / Single or All	Single or All
Selection	Multi display	Dropdown / List	Dropdown
Selection	Visible rows	2 – 20 (Multi + List)	5
Selection	Default selection	None / Max / Min	Max
Selection	Default behavior	On Load / Only When Empty	On Load
Selection	Sort direction	Descending / Ascending	Descending
Selection	Show Select All	On / Off	On
Selection	Select All label	text (empty = localized All)	empty
Selection	Multi selection label	text with {0} (empty = localized {0} selected)	empty
Selection	Clear behavior	Default / All / None	Default
Slicer header	Show, title text, font, colour, clear button		on
Slicer box	Font, colour, background, border, radius		native-like
Dropdown list	Background, font colour		white / dark grey

Single or All means exactly one value or no filter at all — two individual values can never be selected together. The closed control always shows the real state: the value, the Select All label, or 2 selected in Multi.

Multi-select

Multi has two presentations, chosen with Multi display.

Dropdown — the compact closed box. The option list marks selected values with ☑ / ☐; each pick toggles one value and applies the filter immediately. The visual then tries to reopen the native dropdown so further values can be ticked without clicking again. That reopen depends on the host and browser exposing HTMLSelectElement.showPicker() (Chromium 121+); where it is unavailable or blocked, the dropdown closes after each choice and is reopened manually. Selection is never affected.

List — a native multi-select list box, always visible, Visible rows tall, scrolling past that. A plain click toggles a row; Ctrl/Cmd is not required. Keyboard navigation keeps the platform's own behaviour.

In both, All clears the individual selection and removes the visual's filter; selecting a value while All is active leaves the All state; removing the last selected value falls back to All.

Power BI Report Server

AutoDefaultSlicer has been tested end-to-end with Power BI Report Server.

• Tested with: Power BI Desktop, Power BI Desktop for Power BI Report Server, and Power BI Report Server (rendering, filtering, default selection, Multi modes, and publishing).
• apiVersion: 5.3.0. Every Power BI Report Server release since September 2023 ships a Custom Visual API of 5.4.0 or newer (5.10.0 from September 2024 onward), so the API surface this visual uses is available on those servers. No API introduced after 5.3.0 is used.
• Requirements: custom visuals enabled on the server (EnableCustomVisuals, on by default), and the report authored in Power BI Desktop optimized for Power BI Report Server. The visual travels inside the .pbix; nothing is installed on the server itself.
• Design constraints kept for Report Server: no modal dialogs, no external resources, no APIs newer than 5.3.0; the packaged bundle is exercised by tests on every build.

See docs/report-server.md for the version table and the reasoning behind the API choice.

Limitations

• A custom visual cannot draw outside its own area. That is why the option list is a native <select>: its popup is drawn by the browser and is not clipped. The trade-off is that the popup cannot be styled beyond the closed box, and there is no search box inside it (type-ahead works instead).
• Multi + Dropdown auto-reopen is best effort, as described above.
• List mode: Shift-click ranges are not implemented for the mouse; keyboard Shift+arrow ranges work because they are native.
• Selection is not saved with the report. This is deliberate: the default rule wins on every open. Use Default behavior = Only When Empty to honour a saved filter instead.
• Bookmarks work within a session, not across a reload.
• Two UI languages ship (English, Spanish); others fall back to English.

More detail on behaviour, edge cases and design decisions is in docs/behavior.md.

Development

npm install
npm run typecheck
npm run lint
npm test
npm run package     # builds dist/*.pbiviz and runs the packaged-bundle tests

Node.js 18 or newer. The .pbiviz is written to dist/. See docs/development.md for the project layout, the test suites and how localization resources are organized, and CONTRIBUTING.md for the pull request workflow.

License

MIT © Neoblastergx