Find features in a feature table which match an SQL query.
Use case
Query expressions can be used in ArcGIS to select a subset of features from a feature table. This is most useful in large or complicated data sets. A possible use case might be on a feature table marking the location of street furniture through a city. A user may wish to query by a TYPE column to return "benches". In this sample, we query a U.S. state by STATE_NAME from a feature table containing all U.S. states.
How to use the sample
Input the name of a U.S. state into the text field. When you click the search icon on the device keypad or press the enter key, a query is performed and the matching features are highlighted or an error is returned.
How it works
- Create a
ServiceFeatureTable
using the URL of a feature service. - Create a
QueryParameters
with a where clause specified usingwhereClause()
. - Perform the query using
queryFeatures(queryParameters)
on the service feature table. - When complete, the query will return a
FeatureQueryResult
which can be iterated over to get the matching features.
Relevant API
- FeatureLayer
- FeatureQueryResult
- QueryParameters
- ServiceFeatureTable
About the data
This sample uses U.S. State polygon features from the USA 2016 Daytime Population feature service.
Additional information
This sample uses the GeoView-Compose Toolkit module to be able to implement a composable MapView.
Tags
geoview-compose, query, search, toolkit
Sample Code
/* Copyright 2023 Esri
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
*/
package com.esri.arcgismaps.sample.queryfeaturetable.components
import android.app.Application
import androidx.compose.runtime.getValue
import androidx.compose.runtime.mutableStateOf
import androidx.compose.runtime.setValue
import androidx.lifecycle.AndroidViewModel
import com.arcgismaps.Color
import com.arcgismaps.data.FeatureQueryResult
import com.arcgismaps.data.QueryParameters
import com.arcgismaps.data.ServiceFeatureTable
import com.arcgismaps.geometry.Point
import com.arcgismaps.geometry.SpatialReference
import com.arcgismaps.mapping.ArcGISMap
import com.arcgismaps.mapping.BasemapStyle
import com.arcgismaps.mapping.Viewpoint
import com.arcgismaps.mapping.layers.FeatureLayer
import com.arcgismaps.mapping.symbology.SimpleFillSymbol
import com.arcgismaps.mapping.symbology.SimpleFillSymbolStyle
import com.arcgismaps.mapping.symbology.SimpleLineSymbol
import com.arcgismaps.mapping.symbology.SimpleLineSymbolStyle
import com.arcgismaps.mapping.symbology.SimpleRenderer
import com.arcgismaps.toolkit.geoviewcompose.MapViewProxy
import com.esri.arcgismaps.sample.queryfeaturetable.R
import com.esri.arcgismaps.sample.sampleslib.components.MessageDialogViewModel
import kotlinx.coroutines.CoroutineScope
import kotlinx.coroutines.launch
import java.util.Locale
class MapViewModel(
application: Application,
private val sampleCoroutineScope: CoroutineScope
) : AndroidViewModel(application) {
// create a ViewModel to handle dialog interactions
val messageDialogVM: MessageDialogViewModel = MessageDialogViewModel()
// create a service feature table and a feature layer from it
private val serviceFeatureTable: ServiceFeatureTable = ServiceFeatureTable(
application.getString(R.string.us_daytime_population_url)
)
// create the feature layer using the service feature table
private val featureLayer: FeatureLayer by lazy {
FeatureLayer.createWithFeatureTable(serviceFeatureTable)
}
// map used to display the feature layer
val map = ArcGISMap(BasemapStyle.ArcGISTopographic)
private var usaViewpoint = Viewpoint(
center = Point(-11e6, 5e6, SpatialReference.webMercator()),
scale = 1e8
)
// create a MapViewProxy to handle MapView operations
var mapViewProxy by mutableStateOf(MapViewProxy())
init {
// use symbols to show U.S. states with a black outline and yellow fill
val lineSymbol = SimpleLineSymbol(
style = SimpleLineSymbolStyle.Solid,
color = Color.black,
width = 1.0f
)
val fillSymbol = SimpleFillSymbol(
style = SimpleFillSymbolStyle.Solid,
color = Color.fromRgba(255, 255, 0, 255),
outline = lineSymbol
)
// set featurelayer properties
featureLayer.apply {
// set renderer for the feature layer
renderer = SimpleRenderer(fillSymbol)
opacity = 0.8f
maxScale = 10000.0
}
// add the feature layer to the map's operational layers
map.apply {
initialViewpoint = usaViewpoint
operationalLayers.add(featureLayer)
}
}
/**
* Search for a U.S. state using [searchQuery] in the feature table, and if found add it
* to the featureLayer, zoom to it, and select it.
*/
fun searchForState(searchQuery: String) {
// clear any previous selections
featureLayer.clearSelection()
// create a query for the state that was entered
val queryParameters = QueryParameters().apply {
// make search case insensitive
whereClause = ("upper(STATE_NAME) LIKE '%" + searchQuery.uppercase(Locale.US) + "%'")
}
sampleCoroutineScope.launch {
// call select features
val featureQueryResult = serviceFeatureTable.queryFeatures(queryParameters).getOrElse {
messageDialogVM.showMessageDialog(it.message.toString(), it.cause.toString())
} as FeatureQueryResult
val feature = featureQueryResult.firstOrNull()
if (feature != null) {
// select the feature
featureLayer.selectFeature(feature)
// get the extent of the first feature in the result to zoom to
val envelope = feature.geometry?.extent
?: return@launch messageDialogVM.showMessageDialog("Error retrieving geometry extent")
// update the map's viewpoint to the feature's geometry
mapViewProxy.setViewpointGeometry(envelope)
} else {
messageDialogVM.showMessageDialog("No states found with name: $searchQuery")
}
}
}
}