FilterList

Shows a list of filters for refining search results.

Signature

FilterListConnector.All(
    filters: List<Filter>,
    filterState: FilterState,
    selectionMode: SelectionMode,
    groupID: FilterGroupID
)

Explore example code

About this widget

FilterList is a filtering view that displays any kind of filters, and lets users refine the search results by selecting them.

Compared to the RefinementList, which takes its values from the search response facet, this widget displays filters that you add yourself.

Examples

Kotlin

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 price = "price"
    val filters = listOf(
        Filter.Numeric(price, 5..10),
        Filter.Tag("coupon"),
        Filter.Facet(color, "red"),
        Filter.Facet(color, "black"),
        Filter.Numeric(price, NumericOperator.Greater, 100)
    )
    val groupAll = groupAnd(all)
    val filterListConnector = FilterListConnector.All(
        filters = filters,
        filterState = filterState,
        groupID = groupAll
    )
    val connection = ConnectionHandler(filterListConnector, searcher.connectFilterState(filterState))

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        val filterListView: FilterListView.All = MyFilterListAdapter() // your `FilterListView.All` 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 components and connect them manually, use the following components:

• Searcher. The Searcher that handles your searches.
• FilterState. The current state of the filters.
• FilterListViewModel.All. The logic applied to the filters.
• FilterListView.All. The view that renders the filters.
• FilterPresenter. Optional. The presenter to customize the display of the filters.

Kotlin

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 price = "price"
    val filters = listOf(
        Filter.Numeric(price, 5..10),
        Filter.Tag("coupon"),
        Filter.Facet(color, "red"),
        Filter.Facet(color, "black"),
        Filter.Numeric(price, NumericOperator.Greater, 100)
    )
    val viewModel = FilterListViewModel.All(filters)
    val connection = ConnectionHandler()

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        val view: FilterListView.All =  MyFilterListAdapter() // your `FilterListView.All` 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

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 price = "price"
    val filters = listOf(
        Filter.Numeric(price, 5..10),
        Filter.Tag("coupon"),
        Filter.Facet(color, "red"),
        Filter.Facet(color, "black"),
        Filter.Numeric(price, NumericOperator.Greater, 100)
    )
    val groupAll = groupAnd(all)
    val filterListState = FilterListState<Filter>()
    val filterList = FilterListConnector.All(
        filters = filters,
        filterState = filterState,
        groupID = groupAll
    )
    val connections = ConnectionHandler(filterList)

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

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

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

Parameters

filters · List<Filter> · required

The filters to display.

filterState · FilterState · required

The FilterState that will hold your filters.

selectionMode · SelectionMode

Whether the list can have Single or Multiple selections.

groupID · FilterGroupID

The identifier for the group of filters.

View

view · FilterListView.All

The view that renders the filters.

Kotlin

import com.algolia.instantsearch.filter.Filter

val view: FilterListView.All = MyFilterListAdapter()
filterListConnector.connectView(view)

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

    override var onSelection: Callback<Filter>? = 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>>) {
        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
    }
}