FilterState

Provides interface for managing applied filters.

About this widget

A FilterState is a class that holds one or several filters, organized in groups. The FilterState can be modified at any moment by adding or removing filters, which will be applied to searches performed by the connected Searcher.

You can use three filter types:

• Filter.Facet
• Filter.Numeric
• Filter.Tag

A group of filters must be identified by a FilterGroupID. A FilterGroupID must have:

• A name
• A FilterOperator, which can either be FilterOperator.And or FilterOperator.Or

A FilterOperator indicates which type of boolean operator should be applied between each filter in the group.

See also:

• Get started with imperative UI
• Filtering
• Filtering and boolean operators

Explore example code

Browse the FilterState example code on GitHub.

Examples

Add and remove filters from a FilterState.

Kotlin

import com.algolia.instantsearch.filter.Filter

val filterState = FilterState()
val filterGroupID = FilterGroupID("myGroup", FilterOperator.And)
val color = "color"
val red = Filter.Facet(color, "red")
val green = Filter.Facet(color, "green")
val blue = Filter.Facet(color, "blue")

filterState.add(filterGroupID, red, green, blue)
// "color:red AND color:green AND color:blue"
filterState.remove(filterGroupID, green)
// "color:red AND color:blue"

Notify and listen to changes.

Kotlin

import com.algolia.instantsearch.filter.Filter

val filterState = FilterState()
val filterGroupID = FilterGroupID("myGroup", FilterOperator.And)
val color = "color"
val facets = setOf(
    Filter.Facet(color, "red"),
    Filter.Facet(color, "green"),
    Filter.Facet(color, "blue")
)
filterState.notify {
    add(filterGroupID, facets)
}
filterState.filters.subscribe { filters ->
    assertEquals(facets, filters.getFacetFilters(filterGroupID))
}

Convert a FilterState to an SQL-like string expression which can be used with search parameters.

Kotlin

import com.algolia.client.model.search.SearchParamsObject

val query = SearchParamsObject()

val filtersString = FilterGroupsConverter.SQL(filterState.toFilterGroups())
val queryWithFilters = query.copy(filters = filtersString)