List related features

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
// Copyright 2022 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.Mapping;
using Esri.ArcGISRuntime.Maui;
using Esri.ArcGISRuntime.Portal;
using Colors = System.Drawing.Color;

namespace ArcGIS.Samples.ListRelatedFeatures
{
    [ArcGIS.Samples.Shared.Attributes.Sample(
        name: "List related features",
        category: "Data",
        description: "List features related to the selected feature.",
        instructions: "Tap on a feature to select it. The related features will be displayed in a list.",
        tags: new[] { "features", "identify", "query", "related", "relationship", "search" })]
    public partial class ListRelatedFeatures : ContentPage
    {
        // URL to the web map
        private readonly Uri _mapUri =
            new Uri("https://arcgisruntime.maps.arcgis.com/home/item.html?id=dcc7466a91294c0ab8f7a094430ab437");

        // Reference to the feature layer
        private FeatureLayer _myFeatureLayer;

        public ListRelatedFeatures()
        {
            InitializeComponent();

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

        private async Task Initialize()
        {
            try
            {
                // Create the portal item from the URL to the webmap
                PortalItem alaskaPortalItem = await PortalItem.CreateAsync(_mapUri);

                // Create the map from the portal item
                Map myMap = new Map(alaskaPortalItem);

                // Add the map to the mapview
                MyMapView.Map = myMap;

                // Wait for the map to load
                await myMap.LoadAsync();

                // Get the feature layer from the map
                _myFeatureLayer = (FeatureLayer)myMap.OperationalLayers.First();

                // Make the selection color yellow.
                MyMapView.SelectionProperties.Color = Colors.Yellow;

                // Listen for GeoViewTapped events
                MyMapView.GeoViewTapped += MyMapViewOnGeoViewTapped;
            }
            catch (Exception e)
            {
                await Application.Current.MainPage.DisplayAlert("Error", e.ToString(), "OK");
            }
        }

        private async void MyMapViewOnGeoViewTapped(object sender, GeoViewInputEventArgs e)
        {
            try
            {
                // Clear any existing feature selection and results list
                _myFeatureLayer.ClearSelection();
                MyResultsView.ItemsSource = null;

                // Identify the tapped feature
                IdentifyLayerResult results = await MyMapView.IdentifyLayerAsync(_myFeatureLayer, e.Position, 10, false);

                // Return if there are no results
                if (results.GeoElements.Count < 1) { return; }

                Status.Text = "Loading...";

                // Get the first result
                ArcGISFeature myFeature = (ArcGISFeature)results.GeoElements.First();

                // Select the feature
                _myFeatureLayer.SelectFeature(myFeature);

                // Get the feature table for the feature
                ArcGISFeatureTable myFeatureTable = (ArcGISFeatureTable)myFeature.FeatureTable;

                // Query related features
                IReadOnlyList<RelatedFeatureQueryResult> relatedFeaturesResult = await myFeatureTable.QueryRelatedFeaturesAsync(myFeature);

                // Create a list to hold the formatted results of the query
                List<String> queryResultsForUi = new List<string>();

                // For each query result
                foreach (RelatedFeatureQueryResult result in relatedFeaturesResult)
                {
                    // And then for each feature in the result
                    foreach (Feature resultFeature in result)
                    {
                        // Get a reference to the feature's table
                        ArcGISFeatureTable relatedTable = (ArcGISFeatureTable)resultFeature.FeatureTable;

                        // Get the display field name - this is the name of the field that is intended for display
                        string displayFieldName = relatedTable.LayerInfo.DisplayFieldName;

                        // Get the name of the feature's table
                        string tableName = relatedTable.TableName;

                        // Get the display name for the feature
                        string featureDisplayname = resultFeature.Attributes[displayFieldName].ToString();

                        // Create a formatted result string
                        string formattedResult = $"{tableName} - {featureDisplayname}";

                        // Add the result to the list
                        queryResultsForUi.Add(formattedResult);
                    }
                }

                // Update the UI with the result list
                MyResultsView.ItemsSource = queryResultsForUi;
                Status.Text = "Tap a park (green) to see related features.";
            }
            catch (Exception ex)
            {
                await Application.Current.MainPage.DisplayAlert("Error", ex.ToString(), "OK");
            }
        }
    }
}