Feature layer query

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
// Copyright 2016 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.

using Esri.ArcGISRuntime.Data;
using Esri.ArcGISRuntime.Geometry;
using Esri.ArcGISRuntime.Mapping;
using Esri.ArcGISRuntime.Symbology;
using System;
using System.Collections.Generic;
using System.Drawing;
using System.Linq;
using System.Threading.Tasks;
using System.Windows;

namespace ArcGIS.WPF.Samples.FeatureLayerQuery
{
    [ArcGIS.Samples.Shared.Attributes.Sample(
        name: "Feature layer query",
        category: "Data",
        description: "Find features in a feature table which match an SQL query.",
        instructions: "Input the name of a U.S. state into the text field. When you click the button, a query is performed and the matching features are highlighted or an error is returned.",
        tags: new[] { "query", "search" })]
    public partial class FeatureLayerQuery
    {
        // Create reference to service of US States.
        private string _statesUrl = "https://services.arcgis.com/jIL9msH9OI208GCb/arcgis/rest/services/USA_Daytime_Population_2016/FeatureServer/0";

        // Create globally available feature table for easy referencing.
        private ServiceFeatureTable _featureTable;

        // Create globally available feature layer for easy referencing.
        private FeatureLayer _featureLayer;

        public FeatureLayerQuery()
        {
            InitializeComponent();

            // Create the UI, setup the control references and execute initialization.
            Initialize();
        }

        private void Initialize()
        {
            // Create new Map with basemap.
            Map myMap = new Map(BasemapStyle.ArcGISTopographic);

            // Create and set initial map location.
            MapPoint initialLocation = new MapPoint(-11000000, 5000000, SpatialReferences.WebMercator);
            myMap.InitialViewpoint = new Viewpoint(initialLocation, 100000000);

            // Create feature table using a URL.
            _featureTable = new ServiceFeatureTable(new Uri(_statesUrl));

            // Create feature layer using this feature table. Make it slightly transparent.
            _featureLayer = new FeatureLayer(_featureTable)
            {
                Opacity = 0.6,
                // Work around service setting.
                MaxScale = 10
            };

            // Create a new renderer for the States Feature Layer.
            SimpleLineSymbol lineSymbol = new SimpleLineSymbol(SimpleLineSymbolStyle.Solid, Color.Black, 1);
            SimpleFillSymbol fillSymbol = new SimpleFillSymbol(SimpleFillSymbolStyle.Solid, Color.Transparent, lineSymbol);

            // Set States feature layer renderer.
            _featureLayer.Renderer = new SimpleRenderer(fillSymbol);

            // Add feature layer to the map.
            myMap.OperationalLayers.Add(_featureLayer);

            // Adjust the selection color.
            MyMapView.SelectionProperties.Color = Color.Cyan;

            // Assign the map to the MapView.
            MyMapView.Map = myMap;
        }

        private void OnQueryClicked(object sender, RoutedEventArgs e)
        {
            // Remove any previous feature selections that may have been made.
            _featureLayer.ClearSelection();

            // Begin query process.
            _ = QueryStateFeature(QueryEntry.Text);
        }

        private async Task QueryStateFeature(string stateName)
        {
            try
            {
                // Create a query parameters that will be used to Query the feature table.
                QueryParameters queryParams = new QueryParameters();

                // Trim whitespace on the state name to prevent broken queries.
                string formattedStateName = stateName.Trim().ToUpper();

                // Construct and assign the where clause that will be used to query the feature table.
                queryParams.WhereClause = "upper(STATE_NAME) LIKE '%" + formattedStateName + "%'";

                // Query the feature table.
                FeatureQueryResult queryResult = await _featureTable.QueryFeaturesAsync(queryParams);

                // Cast the QueryResult to a List so the results can be interrogated.
                List<Feature> features = queryResult.ToList();

                if (features.Any())
                {
                    // Create an envelope.
                    EnvelopeBuilder envBuilder = new EnvelopeBuilder(SpatialReferences.WebMercator);

                    // Loop over each feature from the query result.
                    foreach (Feature feature in features)
                    {
                        // Add the extent of each matching feature to the envelope.
                        envBuilder.UnionOf(feature.Geometry.Extent);

                        // Select each feature.
                        _featureLayer.SelectFeature(feature);
                    }

                    // Zoom to the extent of the selected feature(s).
                    await MyMapView.SetViewpointGeometryAsync(envBuilder.ToGeometry(), 50);
                }
                else
                {
                    MessageBox.Show("Retry your query with a valid state name, like 'California'.", "State not found!");
                }
            }
            catch (Exception ex)
            {
                MessageBox.Show("An error occurred.\n" + ex, "Sample error");
            }
        }
    }
}