Feature layer query

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 tap the button, a query is performed and the matching features are highlighted or an error is returned.

How it works

1. Create a ServiceFeatureTable using the URL of a feature service.
2. Create a QueryParameters with a where clause specified using the WhereClause property.
3. Perform the query using QueryFeaturesAsync(query) on the service feature table.
4. 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.

Tags

query, search

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<?xml version="1.0" encoding="utf-8" ?>
<ContentPage x:Class="ArcGISRuntime.Samples.FeatureLayerQuery.FeatureLayerQuery"
             xmlns="http://xamarin.com/schemas/2014/forms"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             xmlns:esriUI="clr-namespace:Esri.ArcGISRuntime.Xamarin.Forms;assembly=Esri.ArcGISRuntime.Xamarin.Forms">
    <Grid>
        <Grid.RowDefinitions>
            <RowDefinition Height="auto" />
            <RowDefinition Height="*" />
        </Grid.RowDefinitions>
        <StackLayout Orientation="Vertical">
            <Entry x:Name="queryEntry" Text="New York" />
            <Button Clicked="OnQueryClicked" Text="Query" />
        </StackLayout>
        <esriUI:MapView x:Name="myMapView" Grid.Row="1" />
    </Grid>
</ContentPage>