Query

A query provides the ability to return a subset of features from a dataset based on any combination of attribute, spatial, and temporal (time) criteria.

  • Attribute criteria are defined with a standard SQL expression based on the available attribute fields.
  • Spatial criteria use a geometry and a spatial relationship (within, contains, intersect, and so on).
  • A temporal filter can be defined using a single date or time, or a range.

You can also perform queries to return related features, a feature count, an extent containing all features meeting your criteria, or statistical information about a dataset.

How query works

Query criteria is defined using a query parameters object. This is where you specify the attribute, spatial, and/or temporal inputs. Most ArcGIS Runtime queries take query parameters as an input to define the query criteria as well as some preferences for the results. When the query is executed against a specific dataset (feature table), results are returned as a collection of features.

A query does not require that each type of criteria be defined. Query criteria are only evaluated if explicitly defined (missing temporal criteria, for example, means not to filter the results according to time).

Relevant classes and members in the API ref

Query parameters

Query parameters define the query criteria using:

  • An SQL expression for attribute criteria
  • Geometry and a spatial relationship for spatial criteria
  • A date/time or a range of dates/times for temporal criteria

Some spatial relationships you can define for the query include:

  • Intersects: part of a feature is contained in the geometry.
  • Touches: a feature touches the border of the geometry.
  • Crosses: a feature crosses the geometry.
  • Within: a feature is completely enclosed by the geometry.
  • Contains: part or all of a feature is contained within the geometry.

The query parameters can be used in a standard query to return features, or in queries that return a feature count or extent. You can also use the query parameters to make a selection in the map showing the features that match the criteria.

Specialized query parameters are used for queries that return statistics or related features. In addition to query criteria, these query parameters define things like the type of statistics to return or the relationships to evaluate.

This example uses spatial criteria to find features inside a polygon. Instead of executing a query on the FeatureTable, however, the query parameters are simply passed to the FeatureLayer to display features that meet the criteria as a new selection.

Use dark colors for code blocksCopy
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 
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
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
// create a buffer from the point
final Polygon searchGeometry = GeometryEngine.buffer(mapPoint, 5000);

// create a query to find which features are contained by the query geometry
QueryParameters queryParams = new QueryParameters();
queryParams.setGeometry(searchGeometry);
queryParams.setSpatialRelationship(QueryParameters.SpatialRelationship.CONTAINS);

// select based on the query
final ListenableFuture<FeatureQueryResult> selectFuture =
    arcGisFeatureTable.getLayer().selectFeaturesAsync(queryParams, FeatureLayer.SelectionMode.NEW);
// if required, can listen to the future to perform an action when features are selected

Query results

Query results typically provide a collection of features. You can iterate the result features to display them on the map, read their attributes, and so on. A query for statistics returns a collection of records that describe the requested statistics for features in the dataset. Queries for feature count or extent return a number and an envelope respectively.

Geometry for the query results can be returned in a specified spatial reference by specifying the output spatial reference in the query parameters. If a spatial reference is not specified, results will be returned in the spatial reference of the dataset. Most often, you will need the result features in the same spatial reference as your app's map.

You can also set a maximum number of features to return in the result. This is useful in situations where you might only need a subset of features that meet your criteria. It may also improve performance by limiting the amount of information returned with the result.

Identify

Identify is like a shortcut for a spatial query. It allows you to quickly answer the question: what is here? It gives users a quick way to explore and learn about the map or scene content by tapping or clicking. Information returned from an identify operation can be shown in pop-ups or other UI components in your app. Unlike a query, you can't provide attribute or time criteria to filter results. Identify returns geoelements or graphics at the specified location.

Use dark colors for code blocksCopy
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 
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
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
//specifying the layer to identify, where to identify, tolerance around point, to return pop-ups only, and
// maximum results
final ListenableFuture<IdentifyLayerResult> identifyFuture =
  mapView.identifyLayerAsync(layer, screenPoint, 20, false, 25);

// add a listener to the future
identifyFuture.addDoneListener(() -> {
  try {
    // get the identify results from the future - returns when the operation is complete
    IdentifyLayerResult identifyLayerResult = identifyFuture.get();

    // a reference to the feature layer can be used, for example, to select identified features
    if (identifyLayerResult.getLayerContent() instanceof FeatureLayer) {
      FeatureLayer featureLayer = (FeatureLayer) identifyLayerResult.getLayerContent();
      // select all features that were identified
      List<Feature> features =
        identifyLayerResult.getElements().stream().map(f -> (Feature) f).collect(Collectors.toList());
      featureLayer.selectFeatures(features);
    }

  } catch (InterruptedException | ExecutionException ex) {
    // ... deal with exceptions thrown from the async identify operation
  }
});

Identify geoelements and graphics

You can identify geoelements from layers or graphics from graphics overlays.

Relevant classes and members in the API ref

The following API is used to identify features in layers. The identify layers methods are defined in GeoView.

The following API is used to identify graphics in graphic overlays. The identify graphics overlay methods are defined in GeoView.

Identify parameters

The identify methods have very similar signatures. The following are parameters they can take.

  • screenPoint: the location on the screen tapped or clicked by the user.
  • tolerance: the radius (in pixels) of a circle centered at the screen point, within which to identify geoelements or graphics.
  • returnPopupsOnly: true to identify pop-ups only. False to identify geoelements or graphics as well.
  • maximumResults: the maximum number of geoelements or graphics to return. If you use one of the identify method overloads that omits this parameter, the result contains only the topmost visible item for each layer or graphic overlay identified. If you are identifying on a group layer or a map image layer, this parameter determines the non-zero number of results per sublayer. (See Identify on group layers and Identify on map image layers.)

Identify results

The results of calling one of the identify methods for a specific layer or for all layers are available in an IdentifyLayerResult or a collection of IdentifyLayerResult, respectively. You can get the geoelements from an identify layer result.

The results of calling one of the identify methods for a specify graphics overlay or for all graphics overlays are available in an IdentifyGraphicsOverlayResult or a collection of IdentifyGraphicsOverlayResult, respectively. You can get the graphics from the identify graphics overlay result.

Identify on other layer types

While any Layer can be identified, the following describe considerations for some of them.

Identify on group layers

If you want to perform an identify on a group layer GroupLayer, call the identify layer method and pass the group layer as the layer argument. Identify operates on all the child layers of the group layer. The method returns an IdentifyLayerResult for the group layer, but the result has no geoelements for the group layer. Instead, you should access results for child layers using getSublayerResults() in the IdentifyLayerResult. The sublayer results property is a collection of IdentifyLayerResult, one for each child layer.

If you want to perform an identify on all layers, some of which are group layers, call the identify layers method. The collection returned contains no identify layer result for a group layer, but has an identify layer result for each of its child layers. Effectively, this behavior treats the child layers as independent layers and otherwise ignores the group layers.

When calling identify methods that take a maximumResults parameter, this value determines the non-zero number of features returned per sublayer. See Identify parameters.

Identify on map image layers

You can use the identify layers method to identify against map image layers and tiled map layers. Iterate over the results collection, and use the layer content property of IdentifyLayerResult to test if the LayerContent is an ArcGISMapImageLayer or ArcGISMapImageSublayer.

The following points apply when identifying against map image layers:

  • Results are returned as features; unlike other features, however, they will not have a reference to a FeatureTable.
  • Map image layers may have one or more sublayers. Identify results from map image layers reflect this structure, and return results for each sublayer separately. (Note that if you have specified a maximum number of results to return, this value applies per sublayer.)

Identify on raster layers

Identify on raster layers returns the RasterCell value for a tapped location in a MapView or SceneView. The identified RasterLayer can be local on the device or from a web service layer hosted on ArcGIS Online or ArcGIS Enterprise. Identify returns raster cell values to display in a simple callout, or if a pop-up is configured for the raster layer, the information can be displayed in a formatted UI.

For mosaicked images, a mosaic rule defines how the individual rasters are combined. When identifying images mosaicked from a collection of images, the values returned from identify can vary according to the mosaic rule settings. You can use the default rule defined with the service or, starting with 100.9.0, define rule settings to control how overlapping areas in the mosaic are handled. Rendering rules applied on the raster layer on the client, as well as information from attribute tables (if present), will also be represented in the identify results.

Identify features in a WMS layer

WMS layers differ from other layers, as they do not support returning individual attributes or geometry for a feature. WMS services perform identify on the server and return HTML documents describing identified features. Each feature will be a WmsFeature, which allows you access to the the returned HTML document string. Use the feature's attributes property to get the dictionary of attributes, and then find the attribute that has the key HTML. The value is an HTML string suitable for display in a web view.

It is impossible to get the geometry for an identified (or any other) WMS feature. An identified WMS feature's geometry will always be null. Consequently, WMS layers do not support feature selection/highlight.

Display filters

Display filters limit the number of features displayed to reduce clutter in a map or scene. Use FeatureLayer.setDisplayFilterDefinition when you want to draw a subset of features while maintaining access to all of them. Unlike a definition expression, features hidden by a display filter are available for selection, identify, editing, and geoprocessing operations.

Display filters can be added to maps and scenes authored with ArcGIS Runtime, or published in web maps using ArcGIS Pro 2.9 or higher.

Tutorials

Samples

Feature layer query

Statistical query

Time based query

List related features

Query map image sublayer

Statistical query (group and sort)

Feature layer definition expression

Identify layers

Identify raster cell

Identify graphics

Scene layer selection

Identify KML Features

Your browser is no longer supported. Please upgrade your browser for the best experience. See our browser deprecation post for more details.