rfellows opened a new pull request, #11159: URL: https://github.com/apache/nifi/pull/11159
# Summary [NIFI-15853](https://issues.apache.org/jira/browse/NIFI-15853) This pull request fixes connector wizard properties whose allowable values must be loaded from the backend (`allowableValuesFetchable === true` with no static `allowableValues`). Previously those properties were rendered as a plain text control and never triggered the allowable-values request, so users could not pick from server-provided options. The fix introduces a reusable **SearchableSelect** component (Material-based, `ControlValueAccessor`) and routes both **static** and **dynamic** allowable values through it. **ConnectorPropertyInput** now emits `requestAllowableValues` exactly once per fetchable control when the step loads (guarded by `hasFetchedDynamicValues`), and resets that guard when the bound descriptor's `property.name` changes so a rebound descriptor can refetch. Loading, error, and empty responses are handled with fallbacks so the field stays usable (text input or textarea as appropriate). **STRING_LIST** properties now render as a **multi-select** when allowable values exist (static or dynamic), and as a **comma-separated textarea** when they do not — replacing the previous plain text input for that type. ### Scope - **14 files**, all under `nifi-frontend/src/main/frontend` (~4800 insertions, ~77 deletions on squashed commit `75068da3e3`). ### New / updated shared UI - **`SearchableSelect`** (`libs/shared/src/components/searchable-select/`): filterable overlay select with optional multi-select, sticky search with clear, optional async search and virtual scrolling, optional grouped options, loading/error/empty states, full keyboard navigation, and accessibility (`role="combobox"`, `aria-*`). Spec file adds broad coverage (107 tests covering single/multi select, filter, keyboard navigation, focus management, virtual scrolling, async search, grouping, value-change deduplication, and disabled states). - **`MultiSelectOption`**: extends `MatOption` for options inside the overlay; theming (min-height, padding, hover, selected, keyboard focus) is scoped under `.multi-select-option` so other `mat-select` usages are unaffected. - **`ConnectorPropertyInput`**: template moved to `connector-property-input.component.html`; helpers for input kind and dynamic state (`shouldUseSelect`, `shouldUseTextInput`, `shouldUseTextarea`, `isMultiSelect`, `isDynamicValuesFetchEmpty`, `isDynamicValuesFetchFailed`); textarea branch aligned with text input for validation errors (`required`, `pattern`, `verificationError`, `assetContentMissing` where applicable). - **Exports**: `libs/shared/src/components/index.ts` and `libs/shared/src/types/index.ts` updated for new components/types. ### Visible UX (intentional) - Static `allowableValues` dropdowns now use **searchable-select** instead of **mat-select** (search filter + clear control) so static and dynamic flows share one widget. - **STRING_LIST** is multi-select or textarea as described above. - Option row styling is isolated to searchable-select's option component; other selects in NiFi are not restyled globally. ### Out of scope / follow-ups - **ASSET** / **ASSET_LIST** handling (called out in component doc comment as deferred). - **SECRET** dropdown and **BOOLEAN** slide-toggle alignment with the new patterns. - **Dependency-aware refetch** when a parent property changes (dynamic allowable values are still fetched once per control lifecycle / descriptor identity as implemented here). ### Screenshots _Fetched allowable values from the KafkaToS3 connector for topic names_ <img width="1430" height="1188" alt="Screenshot 2026-04-17 at 09 49 00" src="https://github.com/user-attachments/assets/370e52d1-9e32-48a9-84ff-0f4a89890eb7"; /> # Tracking Please complete the following tracking steps prior to pull request creation. ### Issue Tracking - [x] [Apache NiFi Jira](https://issues.apache.org/jira/browse/NIFI) issue created ### Pull Request Tracking - [x] Pull Request title starts with Apache NiFi Jira issue number, such as `NIFI-15853` - [x] Pull Request commit message starts with Apache NiFi Jira issue number, as such `NIFI-15853` - [ ] Pull request contains [commits signed](https://docs.github.com/en/authentication/managing-commit-signature-verification/signing-commits) with a registered key indicating `Verified` status ### Pull Request Formatting - [ ] Pull Request based on current revision of the `main` branch - [x] Pull request refers to a feature branch with one commit containing changes --- # Verification Please indicate the verification steps performed prior to pull request creation. ### Build - [ ] Build completed using `./mvnw clean install -P contrib-check` - [ ] JDK 21 - [ ] JDK 25 *(Frontend-only change under `nifi-frontend`; full root `contrib-check` should still be run per project norms before merge.)* ### Licensing - [x] New dependencies are compatible with the [Apache License 2.0](https://apache.org/licenses/LICENSE-2.0) according to the [License Policy](https://www.apache.org/legal/resolved.html) - [x] New dependencies are documented in applicable `LICENSE` and `NOTICE` files ### Documentation - [x] Documentation formatting appears as expected in rendered files -- This is an automated message from the Apache Git Service. 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