API Reference / Android Widgets / Filter List (Tag)
Widget signature
FilterListConnector.Tag(
    filters: List<Filter.Tag>,
    filterState: FilterState,
    selectionMode: SelectionMode,
    groupID: FilterGroupID
)

About this widget

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

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

Examples

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class MyActivity : AppCompatActivity() {
    val client = ClientSearch(
        ApplicationID("YourApplicationID"),
        APIKey("YourAPIKey")
    )
    val index = client.initIndex(IndexName("YourIndexName"))
    val searcher = SearcherSingleIndex(index)
    val filterState = FilterState()
    val tags = Attribute("_tags")
    val groupTags = groupOr(tags)
    val filters = listOf(
        Filter.Tag("free shipping"),
        Filter.Tag("coupon"),
        Filter.Tag("free return"),
        Filter.Tag("on sale"),
        Filter.Tag("no exchange")
    )
    val filterListConnector = FilterListConnector.Tag(
        filters = filters,
        filterState = filterState,
        groupID = groupTags
    )
    
    val connection = ConnectionHandler(filterListConnector, searcher.connectFilterState(filterState))

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

  • Searcher: The Searcher that handles your searches.
  • FilterState: The current state of the filters.
  • FilterListViewModel.Tag: The logic applied to the tag filters.
  • FilterListView.Tag: The view that renders the tag filters.
  • FilterPresenter: Optional. The presenter to customize the display of the filters.
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class MyActivity : AppCompatActivity() {
    val client = ClientSearch(
        ApplicationID("YourApplicationID"),
        APIKey("YourAPIKey")
    )
    val index = client.initIndex(IndexName("YourIndexName"))
    val searcher = SearcherSingleIndex(index)
    val filterState = FilterState()
    val filters = listOf(
        Filter.Tag("free shipping"),
        Filter.Tag("coupon"),
        Filter.Tag("free return"),
        Filter.Tag("on sale"),
        Filter.Tag("no exchange")
    )
    val viewModel = FilterListViewModel.Tag(filters)
    val connection = ConnectionHandler()

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

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class MyActivity : AppCompatActivity() {
    val client = ClientSearch(
        ApplicationID("YourApplicationID"),
        APIKey("YourAPIKey")
    )
    val index = client.initIndex(IndexName("YourIndexName"))
    val searcher = SearcherSingleIndex(index)
    val filterState = FilterState()
    val tags = Attribute("_tags")
    val groupTags = groupOr(tags)
    val filters = listOf(
        Filter.Tag("free shipping"),
        Filter.Tag("coupon"),
        Filter.Tag("free return"),
        Filter.Tag("on sale"),
        Filter.Tag("no exchange")
    )
    val filterListState = FilterListState<Filter.Tag>()
    val filterListConnector = FilterListConnector.Tag(
        filters = filters,
        filterState = filterState,
        groupID = groupTags
    )

    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.Tag>`
                    selectableFilter = selectableFacet,
                    onClick = { filterListState.onSelection?.invoke(it) }
                )
            }
        }
        searcher.searchAsync()
    }

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

Parameters

filters
type: List<Filter.Tag>
Required

The tag filters to display.

filterState
type: FilterState
Required

The FilterState that will hold your filters.

selectionMode
type: SelectionMode
default: Multiple
Optional

Whether the list can have Single or Multiple selections.

groupID
type: FilterGroupID
default: FilterGroupID(FilterOperator.And)
Optional

The identifier for the group of filters.

View

view
type: FilterListView.Tag
Required

The view that renders the tag filters.

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val view: FilterListView.Tag = MyFilterListView()
filterListConnector.connectView(view)

// Example of `FilterListView.Tag` implementation
class MyFilterListTagAdapter : FilterListView.Tag,
    ListAdapter<SelectableItem<Filter.Tag>, FilterListViewHolder>(DiffUtilItem()) {
    override var onSelection: Callback<Filter.Tag>? = 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.Tag>>) {
        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
    }
}

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