Query with CQL filters

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
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
// 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.Geometry;
using Esri.ArcGISRuntime.Mapping;
using Esri.ArcGISRuntime.Symbology;

using Color = System.Drawing.Color;

namespace ArcGIS.Samples.QueryCQLFilters
{
    [ArcGIS.Samples.Shared.Attributes.Sample(
        name: "Query with CQL filters",
        category: "Layers",
        description: "Query data from an OGC API feature service using CQL filters.",
        instructions: "Enter a CQL query. Press the \"Apply query\" button to see the query applied to the OGC API features shown on the map.",
        tags: new[] { "CQL", "OGC", "OGC API", "browse", "catalog", "common query language", "feature table", "filter", "query", "service", "web" })]
    public partial class QueryCQLFilters : ContentPage
    {
        private List<string> DefaultWhereClause = new List<string>
        {
            // Sample Query 1: Query for features with an F_CODE attribute property of "AP010".
            "{ \"op\": \"=\", \"args\": [ { \"property\": \"F_CODE\" }, \"AP010\" ] }", // cql2-json query

            // Sample Query 2: Query for features with an F_CODE attribute property similar to "AQ".
            "F_CODE LIKE 'AQ%'", // cql-text query

            // Sample Query 3: use cql2-json to combine "before" and "eq" operators with the logical "and" operator.
           "{\"op\": \"and\", \"args\":[{ \"op\": \"=\", \"args\":[{ \"property\" : \"F_CODE\" }, \"AP010\"]}, { \"op\": \"t_before\", \"args\":[{ \"property\" : \"ZI001_SDV\"},\"2013-01-01\"]}]}"
        };

        // Hold a reference to the OGC feature collection table.
        private OgcFeatureCollectionTable _featureTable;

        // Constants for the service URL and collection id.
        private const string ServiceUrl = "https://demo.ldproxy.net/daraa";

        // Note that the service defines the collection id which can be accessed via OgcFeatureCollectionInfo.CollectionId.
        private const string CollectionId = "TransportationGroundCrv";

        public QueryCQLFilters()
        {
            InitializeComponent();
            _ = Initialize();
        }

        private async Task Initialize()
        {
            // Populate the UI.
            WhereClausePicker.ItemsSource = DefaultWhereClause;
            MaxFeaturesBox.Text = "3000";
            StartDatePicker.Date = new DateTime(2011, 6, 13);
            EndDatePicker.Date = new DateTime(2012, 1, 7);

            // Create the map with topographic basemap.
            MyMapView.Map = new Map(BasemapStyle.ArcGISTopographic);

            try
            {
                LoadingProgressBar.IsVisible = true;

                // Create the feature table from URI and collection id.
                _featureTable = new OgcFeatureCollectionTable(new Uri(ServiceUrl), CollectionId);

                // Set the feature request mode to manual (only manual is currently supported).
                // In this mode, you must manually populate the table - panning and zooming won't request features automatically.
                _featureTable.FeatureRequestMode = FeatureRequestMode.ManualCache;

                // Load the table.
                await _featureTable.LoadAsync();

                // Populate the OGC feature collection table.
                QueryParameters queryParamaters = new QueryParameters();
                queryParamaters.MaxFeatures = 3000;
                await _featureTable.PopulateFromServiceAsync(queryParamaters, false, null);

                // Create a feature layer from the OGC feature collection
                // table to visualize the OAFeat features.
                FeatureLayer ogcFeatureLayer = new FeatureLayer(_featureTable);

                // Set a renderer for the layer.
                ogcFeatureLayer.Renderer = new SimpleRenderer(new SimpleLineSymbol(SimpleLineSymbolStyle.Solid, Color.Red, 1.5));

                // Add the layer to the map.
                MyMapView.Map.OperationalLayers.Add(ogcFeatureLayer);

                // Zoom to the extent of the feature layer/table.
                Envelope tableExtent = _featureTable.Extent;
                if (tableExtent != null && !tableExtent.IsEmpty)
                {
                    await MyMapView.SetViewpointGeometryAsync(tableExtent, 20);
                }
            }
            catch (Exception ex)
            {
                await Application.Current.MainPage.DisplayAlert("Error", ex.Message, "OK");
            }
            finally
            {
                // Update the UI.
                LoadingProgressBar.IsVisible = false;
            }
        }

        public QueryParameters CreateQueryParameters()
        {
            // Create new query parameters.
            var queryParameters = new QueryParameters();

            // Assign the where clause if one is provided.
            if (WhereClausePicker.SelectedItem is string selectedClause) queryParameters.WhereClause = selectedClause;

            // Set the MaxFeatures property to MaxFeaturesBox content.
            if (int.TryParse(MaxFeaturesBox.Text, out int parsedMaxFeatures))
                queryParameters.MaxFeatures = parsedMaxFeatures;

            // Set user date times if provided.
            if (DateSwitch.IsToggled == true)
            {
                DateTime startDate = (StartDatePicker.Date is DateTime userStart) ? userStart : DateTime.MinValue;
                DateTime endDate = (EndDatePicker.Date is DateTime userEnd) ? userEnd : new DateTime(9999, 12, 31);

                // Use the newly created startDate and endDate to create the TimeExtent.
                queryParameters.TimeExtent = new Esri.ArcGISRuntime.TimeExtent(startDate, endDate);
            }

            return queryParameters;
        }

        private async void ApplyQuery_Pressed(object sender, EventArgs e)
        {
            if (_featureTable.LoadStatus != Esri.ArcGISRuntime.LoadStatus.Loaded)
            {
                return;
            }

            try
            {
                LoadingProgressBar.IsVisible = true;

                // Set queryParameters to the user's input
                var queryParameters = CreateQueryParameters();

                // Populate the table with the query, clearing the exist content of the table.
                // Setting outFields to null requests all fields.
                var result = await _featureTable.PopulateFromServiceAsync(queryParameters, true, outFields: null);

                // Report the number of returned features by the query
                NumberOfReturnedFeatures.Text = $"Query returned {result.Count()} features.";

                // Zoom to the extent of the returned features.
                Envelope tableExtent = GeometryEngine.CombineExtents(result.Select(feature => feature.Geometry));
                if (tableExtent != null && !tableExtent.IsEmpty)
                {
                    await MyMapView.SetViewpointGeometryAsync(tableExtent, 20);
                }
            }
            catch (Exception ex)
            {
                await Application.Current.MainPage.DisplayAlert("Error", ex.Message, "OK");
            }
            finally
            {
                // Update the UI.
                LoadingProgressBar.IsVisible = false;
            }
        }

        private void ResetQuery_Pressed(object sender, EventArgs e)
        {
            WhereClausePicker.SelectedItem = null;
            MaxFeaturesBox.Text = "3000";
            DateSwitch.IsToggled = true;
            StartDatePicker.Date = new DateTime(2011, 6, 13);
            EndDatePicker.Date = new DateTime(2012, 1, 7);
        }

        private void DateSwitch_Toggled(object sender, ToggledEventArgs e)
        {
            if (StartDatePicker != null && EndDatePicker != null)
            {
                StartDatePicker.IsEnabled = EndDatePicker.IsEnabled = e.Value;
            }
        }
    }
}