> ## Documentation Index
> Fetch the complete documentation index at: https://algolia.com/llms.txt
> Use this file to discover all available pages before exploring further.

# FilterList (Facet)

> Shows a list of facet filters for refining search results.

export const FlavorSwitcher = ({current, baseHref = "", options = [], label = "InstantSearch framework"}) => {
  if (options.length === 0) {
    return <div className="not-prose" role="alert" style={{
      margin: "0.25rem 0 1.5rem",
      padding: "0.75rem",
      border: "1px solid #f59e0b",
      borderRadius: "0.625rem",
      color: "inherit",
      fontSize: "0.875rem"
    }}>
        FlavorSwitcher requires at least one option.
      </div>;
  }
  const selected = options.find(option => option.value === current) ?? options[0];
  return <div className="not-prose mint-flavor-switcher">
      <style>{`
        .mint-flavor-switcher {
          --mfs-bg: #ffffff;
          --mfs-bg-hover: #f4f4f5;
          --mfs-bg-current: #eef2ff;
          --mfs-border: #d4d4d8;
          --mfs-fg: #18181b;
          --mfs-muted: #71717a;
          --mfs-accent: #4f46e5;
          position: relative;
          width: min(100%, 19rem);
          margin: 0.25rem 0 1.5rem;
          color: var(--mfs-fg);
          font-size: 0.875rem;
          line-height: 1.25rem;
        }

        .dark .mint-flavor-switcher {
          --mfs-bg: #18181b;
          --mfs-bg-hover: #27272a;
          --mfs-bg-current: #272747;
          --mfs-border: #3f3f46;
          --mfs-fg: #fafafa;
          --mfs-muted: #a1a1aa;
          --mfs-accent: #a5b4fc;
        }

        .mint-flavor-switcher details {
          position: relative;
        }

        .mint-flavor-switcher summary {
          display: flex;
          min-height: 2.75rem;
          box-sizing: border-box;
          align-items: center;
          justify-content: space-between;
          gap: 0.75rem;
          padding: 0.625rem 0.75rem;
          border: 1px solid var(--mfs-border);
          border-radius: 0.625rem;
          background: var(--mfs-bg);
          color: var(--mfs-fg);
          cursor: pointer;
          font-weight: 600;
          list-style: none;
          transition: border-color 150ms ease, box-shadow 150ms ease;
        }

        .mint-flavor-switcher summary::-webkit-details-marker {
          display: none;
        }

        .mint-flavor-switcher summary:hover {
          border-color: var(--mfs-accent);
        }

        .mint-flavor-switcher summary:focus-visible {
          outline: 2px solid var(--mfs-accent);
          outline-offset: 2px;
        }

        .mint-flavor-switcher__label {
          overflow: hidden;
          text-overflow: ellipsis;
          white-space: nowrap;
        }

        .mint-flavor-switcher__chevron {
          flex: none;
          transition: transform 150ms ease;
        }

        .mint-flavor-switcher details[open] .mint-flavor-switcher__chevron {
          transform: rotate(180deg);
        }

        .mint-flavor-switcher__menu {
          position: absolute;
          z-index: 50;
          top: calc(100% + 0.375rem);
          left: 0;
          width: 100%;
          box-sizing: border-box;
          margin: 0;
          padding: 0.375rem;
          border: 1px solid var(--mfs-border);
          border-radius: 0.625rem;
          background: var(--mfs-bg);
          box-shadow: 0 12px 30px rgb(0 0 0 / 16%);
          list-style: none;
        }

        .mint-flavor-switcher__menu li {
          margin: 0;
          padding: 0;
        }

        .mint-flavor-switcher__option {
          display: grid;
          gap: 0.125rem;
          padding: 0.625rem 0.75rem;
          border-radius: 0.4rem;
          color: var(--mfs-fg);
          text-decoration: none;
        }

        .mint-flavor-switcher__option:hover {
          background: var(--mfs-bg-hover);
        }

        .mint-flavor-switcher__option:focus-visible {
          outline: 2px solid var(--mfs-accent);
          outline-offset: -2px;
        }

        .mint-flavor-switcher__option[aria-current="page"] {
          background: var(--mfs-bg-current);
          color: var(--mfs-accent);
        }

        .mint-flavor-switcher__name {
          font-weight: 600;
        }

        .mint-flavor-switcher__description {
          color: var(--mfs-muted);
          font-size: 0.8125rem;
        }

        @media (prefers-reduced-motion: reduce) {
          .mint-flavor-switcher summary,
          .mint-flavor-switcher__chevron {
            transition: none;
          }
        }
      `}</style>

      <details>
        <summary aria-label={`${label}: ${selected.label}`}>
          <span className="mint-flavor-switcher__label">{selected.label}</span>
          <svg className="mint-flavor-switcher__chevron" width="18" height="18" viewBox="0 0 24 24" fill="none" stroke="currentColor" strokeWidth="2" strokeLinecap="round" strokeLinejoin="round" aria-hidden="true">
            <path d="m6 9 6 6 6-6" />
          </svg>
        </summary>

        <ul className="mint-flavor-switcher__menu" aria-label={label}>
          {options.map(option => {
    const isCurrent = option.value === selected.value;
    const href = option.href ?? `${baseHref.replace(/\/$/, "")}/${encodeURIComponent(option.value)}`;
    return <li key={option.value}>
                <a className="mint-flavor-switcher__option" href={href} aria-current={isCurrent ? "page" : undefined}>
                  <span className="mint-flavor-switcher__name">
                    {option.label}
                  </span>
                  {option.description ? <span className="mint-flavor-switcher__description">
                      {option.description}
                    </span> : null}
                </a>
              </li>;
  })}
        </ul>
      </details>
    </div>;
};

<div className="mint-flavor-switcher-slot not-prose">
  <FlavorSwitcher
    current="android"
    baseHref="/doc/api-reference/widgets/filter-list-facet"
    options={[
{ value: "ios", label: "iOS", description: "InstantSearch iOS" },
{ value: "android", label: "Android", description: "InstantSearch Android" },
]}
  />
</div>

```kotlin Signature theme={"system"}
FilterListConnector.Facet(
    filters: List<Filter.Facet>,
    filterState: FilterState,
    selectionMode: SelectionMode,
    groupID: FilterGroupID
)
```

<Card title="Explore example code" icon="github" href="https://github.com/algolia/instantsearch-android/tree/master/examples/android">
  Browse the FilterList (Facet) example code on GitHub.
</Card>

## About this widget

`FilterList.Facet` is a filtering view that displays any kind of [facet filters](/doc/api-reference/api-parameters/facetFilters) and lets users refine their search results by selecting them.

Compared to the [`RefinementList`](/doc/api-reference/widgets/refinement-list/android),
which takes its values from the search response facets, this widget displays facet filters that you add yourself.

## Examples

```kotlin Kotlin icon=code theme={"system"}
import com.algolia.instantsearch.filter.Filter

class MyActivity : AppCompatActivity() {
    val searcher = HitsSearcher(
        applicationID = "YourApplicationID",
        apiKey = "YourSearchOnlyAPIKey",
        indexName = "YourIndexName"
    )
    val filterState = FilterState()
    val color = "color"
    val groupColor = groupAnd(color)
    val facetFilters = listOf(
        Filter.Facet(color, "red"),
        Filter.Facet(color, "green"),
        Filter.Facet(color, "blue"),
        Filter.Facet(color, "yellow"),
        Filter.Facet(color, "black")
    )
    val filterListConnector = FilterListConnector.Facet(
        filters = facetFilters,
        filterState = filterState,
        selectionMode = SelectionMode.Single,
        groupID = groupColor
    )
    val connection = ConnectionHandler(filterListConnector, searcher.connectFilterState(filterState))

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        val filterListView: FilterListView.Facet = MyFilterListFacetAdapter() // your `FilterListView.Facet` implementation
        connection += filterListConnector.connectView(filterListView)
        searcher.searchAsync()
    }

    override fun onDestroy() {
        super.onDestroy()
        connection.disconnect()
        searcher.cancel()
    }
}
```

### Low-level API

If you want to fully control the `FilterList.Facet` components and connect them manually, use the following components:

* `Searcher`: The [`Searcher`](/doc/api-reference/widgets/instantsearch/android) that handles your searches.
* `FilterState`: The current state of the filters.
* `FilterListViewModel.Facet`: The logic applied to the facet filters.
* `FilterListView.Facet`: The view that renders the facet filters.
* `FilterPresenter`: Optional. The presenter to customize the display of the filters.

```kotlin Kotlin icon=code theme={"system"}
import com.algolia.instantsearch.filter.Filter

class MyActivity : AppCompatActivity() {
    val searcher = HitsSearcher(
        applicationID = "YourApplicationID",
        apiKey = "YourSearchOnlyAPIKey",
        indexName = "YourIndexName"
    )
    val filterState = FilterState()
    val color = "color"
    val filters = listOf(
        Filter.Facet(color, "red"),
        Filter.Facet(color, "green"),
        Filter.Facet(color, "blue"),
        Filter.Facet(color, "yellow"),
        Filter.Facet(color, "black")
    )
    val viewModel = FilterListViewModel.Facet(filters)
    val connection = ConnectionHandler()

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        val view: FilterListView.Facet = MyFilterListFacetAdapter() // your `FilterListView.Facet` implementation
        connection += searcher.connectFilterState(filterState)
        connection += viewModel.connectFilterState(filterState)
        connection += viewModel.connectView(view)

        searcher.searchAsync()
    }

    override fun onDestroy() {
        super.onDestroy()
        connection.disconnect()
        searcher.cancel()
    }
}
```

### Compose UI

InstantSearch provides the `FilterListState` as a state model, which is an implementation of the `FilterListView` interface.
You need to connect `FilterListState` to the `FilterListConnector` or `FilterListViewModel` like any other `FilterListView` implementation.

```kotlin Kotlin icon=code theme={"system"}
import com.algolia.instantsearch.filter.Filter

class MyActivity : AppCompatActivity() {
  val searcher = HitsSearcher(
      applicationID = "YourApplicationID",
      apiKey = "YourSearchOnlyAPIKey",
      indexName = "YourIndexName"
  )
    val filterState = FilterState()
    val color = "color"
    val groupColor = groupAnd(color)
    val facetFilters = listOf(
        Filter.Facet(color, "red"),
        Filter.Facet(color, "green"),
        Filter.Facet(color, "blue"),
        Filter.Facet(color, "yellow"),
        Filter.Facet(color, "black")
    )
    val filterListState = FilterListState<Filter.Facet>()
    val filterListConnector = FilterListConnector.Facet(
        filters = facetFilters,
        filterState = filterState,
        selectionMode = SelectionMode.Single,
        groupID = groupColor
    )
    val connections = ConnectionHandler(filterListConnector)

    init {
        connections += searcher.connectFilterState(filterState)
        connections += filterListConnector.connectView(filterListState)
    }

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContent {
            filterListState.items.forEach { selectableFacet ->
                FilterRow( // your own UI composable to display `SelectableItem<Filter.Facet>`
                    selectableFilter = selectableFacet,
                    onClick = { filterListState.onSelection?.invoke(it) }
                )
            }
        }
        searcher.searchAsync()
    }

    override fun onDestroy() {
        super.onDestroy()
        connections.disconnect()
        searcher.cancel()
    }
}
```

## Parameters

<ParamField body="filters" type="List<Filter.Facet>" post={["default: listOf()"]} required>
  The facet filters to display.
</ParamField>

<ParamField body="filterState" type="FilterState" required>
  The [`FilterState`](/doc/api-reference/widgets/filter-state/android) that will hold your filters.
</ParamField>

<ParamField body="selectionMode" type="SelectionMode" post={["default: Multiple"]}>
  Whether the list can have `Single` or `Multiple` selections.
</ParamField>

<ParamField body="groupID" type="FilterGroupID" post={["default: FilterGroupID(FilterOperator.Or)"]}>
  The identifier for the group of filters.
</ParamField>

## View

<ParamField body="view" type="FilterListView.Facet">
  The view that renders the filters.

  ```kotlin Kotlin icon=code theme={"system"}
  import com.algolia.instantsearch.filter.Filter

  val view: FilterListView.Facet = MyFilterListFacetAdapter()
  filterListConnector.connectView(view)

  // Example of FilterListView.Facet implementation
  class MyFilterListFacetAdapter : FilterListView.Facet,
      ListAdapter<SelectableItem<Filter.Facet>, FilterListViewHolder>(DiffUtilItem()) {

      override var onSelection: Callback<Filter.Facet>? = null

      override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): FilterListViewHolder {
          return FilterListViewHolder(parent.inflate(R.layout.list_item_selectable))
      }

      override fun onBindViewHolder(holder: FilterListViewHolder, position: Int) {
          val (filter, selected) = getItem(position)
          holder.bind(FilterPresenterImpl()(filter), selected) { onSelection?.invoke(filter) }
      }

      override fun setItems(items: List<SelectableItem<Filter.Facet>>) {
          submitList(items)
      }
  }

  class DiffUtilItem<T : Filter> : DiffUtil.ItemCallback<SelectableItem<T>>() {
      override fun areItemsTheSame(oldItem: SelectableItem<T>, newItem: SelectableItem<T>): Boolean {
          return oldItem.first == newItem.first
      }

      override fun areContentsTheSame(oldItem: SelectableItem<T>, newItem: SelectableItem<T>): Boolean {
          return oldItem == newItem
      }
  }
  ```
</ParamField>