Feature
A layer that can visualize vector/feature data. Feature layers can display Feature data from online sources such as ServiceFeatureTable, WfsFeatureTable or OgcFeatureCollectionTable source, and offline sources such as GeodatabaseFeatureTable, ShapefileFeatureTable, or GeoPackageFeatureTable. You can construct a feature layer object using these sources or you can obtain it directly from a map or scene's collection of GeoModel.operationalLayers.
Feature layers can also be used to store features associated with a utility network. To display features in a FeatureCollectionTable, use FeatureCollectionLayer instead.
Feature layers can be used to display, select, and query features in a layer. Individual features can be queried and filtered based on spatial queries or SQL queries. String comparisons for features queried in service feature tables are case insensitive.
If the underlying feature service or table supports editing, you can use it with a feature layer as a basis for editing geometry, attributes, and attachments.
The features in a feature layer are retrieved as needed by the app. Features can be downloaded from a sync-enabled feature service when the device is connected and cached locally for use when the device is offline. Edits can then be synchronized back to the service.
Functional characteristics
The following sources can be rendered using a feature layer:
Feature service - backed by a ServiceFeatureTable. The feature data from the service is cached locally in the table. New features are retrieved automatically when you navigate the map. The local table cache is discarded when the layer is disposed. If sync is enabled, features can be created, edited, and synchronized back to the server.
Geodatabase - backed by a GeodatabaseFeatureTable. The geodatabase can be a replica of a feature service, which allows synchronizing with the feature service, or taking the content of a feature service offline. Use GeodatabaseSyncTask to synchronize the geodatabase with the service. The geodatabase can also be a mobile geodatabase created by ArcGIS Pro. These geodatabases cannot be synced and use a default renderer.
Shapefile - backed by a ShapefileFeatureTable. Use a feature layer to show the contents of a shapefile (.shp).
Geopackage - backed by a GeoPackageFeatureTable. This uses a feature layer to render the tables in a GeoPackage (.gpkg). A GeoPackage is a data source that conforms to the https://www.ogc.org/standards/geopackage. Geopackage feature tables can be edited and saved, but do not support sync, because there is no backing feature service. This API supports GeoPackage versions 1.0, 1.1, and 1.2.
Web Feature Service (WFS) - backed by a WfsFeatureTable. You can populate the table using QueryParameters or raw XML-encoded GetFeature queries. A WFS feature table only supports the manual cache feature request mode. This API supports OGC WFS[https://www.ogc.org/standards/wfs] versions 2.0.0 and 2.0.2. WFS server implementations are inconsistent in how they expect coordinates to be formatted. Some return and expect coordinates in (x,y) order, while others expect (y,x). This API anticipates the order but you can configure it with the WfsFeatureTable.axisOrder and WfsFeatureTable.filterAxisOrder.
OGC API Features - Backed by an OgcFeatureCollectionTable. You can populate the table using QueryParameters. An OCG feature collection table only supports the manual cache feature request mode. This API supports OGC API - Features - Part 1[https://docs.opengeospatial.org/is/17-069r3/17-069r3.html] and https://docs.opengeospatial.org/is/18-058/18-058.html.
The features displayed in a FeatureLayer are automatically projected to match the map or scene's GeoModel.spatialReference, if necessary. Local tables cannot be projected automatically.
FeatureLayer does not expose every value defined in the web map or web scene specification. You can obtain a dictionary of unsupported values from FeatureLayer.unsupportedJson. The FeatureLayer also provides FeatureLayer.unknownJson to return JSON that is not recognized in the web map or web scene specification.
Performance characteristics
The feature layer offers excellent display performance when zooming and panning the map within the extent of locally cached features. This is because features are drawn natively and full feature information is cached locally in a geodatabase, shapefile, or GeoPackage. Querying features is also efficient, enabling app functions such as real-time updates of query results in a map.
Initially, a local cache must be created. The initial download to the device may require extensive network usage and subsequent local device storage. App memory usage increases with the number and complexity of the features cached. You can eliminate the network usage by provisioning the cache directly to the device in advance.
If the feature layer's FeatureTable is backed by a service it has three feature request modes (FeatureRequestMode) that control how and when features are requested from the service:
On interaction cache - Features are requested automatically for the visible map or scene extent. As the user pans and zooms, features are cached locally. If the user returns to an area where features have already been loaded, the table won't need to download those features again.
Manual cache - Features are manually populated using a call to ServiceFeatureTable.populateFromService(QueryParameters, Boolean, MutableListImpl). Once populated, all queries are made against the local table only. ServiceFeatureTable.populateFromService(QueryParameters, Boolean, MutableListImpl) can be called again to retrieve more features from the service.
On interaction, no cache - Features are requested automatically for the visible map extent. As the user pans and zooms, features outside the visible extent are not cached and must be downloaded again each time.
Since
200.1.0
See also
Types
Properties
A SQL expression which limits the features available for query and display on the feature layer. The definition expression string should follow standard SQL syntax as detailed in the SQL reference for query expressions used in ArcGIS[https://pro.arcgis.com/en/pro-app/latest/help/mapping/navigation/sql-reference-for-elements-used-in-query-expressions.htm] document.
Defines how features are filtered from the display. Use this property to reduce the number of features displayed in the map or scene view. The filter aims to improve data visualization and optimize rendering performance. It only affects the display of features so all features are still available for query methods such as FeatureLayer.selectFeatures(QueryParameters, SelectionMode): Future
Defines properties for dynamically aggregating and summarizing groups of features as the map scale changes. A null value indicates the layer does not use feature reduction. FeatureReduction is only supported for point feature layers in dynamic rendering mode (FeatureRenderingMode.Dynamic).
The collection of LabelDefinition objects that define how labels are displayed.
The mode defines how the feature layer is rendered. FeatureRenderingMode.Static mode is better suited for displaying large datasets (in terms of the number of vertices) and for complex symbology because it does not update the layer's display while pan/zoom operations are in progress.
True if the layer's symbols and labels honor the map's reference scale, otherwise false. If the map has a positive reference scale, and the layer honors it, then symbols and labels are drawn at their specified size when the viewing scale is the same as the reference scale. They will grow or shrink as the view zooms in or out, to keep the symbol a fixed size on the map. If the map has no reference scale, the reference scale is zero, or this feature layer's scaleSymbols property is false, then the symbols and labels will be drawn at their fixed screen size.
The mode defines whether feature tiling is used to retrieve the features from the feature service. The default tiling mode is FeatureTilingMode.EnabledWhenSupported.
Unknown data from the source JSON. Unknown JSON is a dictionary of values not defined in the ArcGIS specification used to create this object but found in the source JSON. If the object is written back to JSON, any unknown JSON data is not persisted. The ArcGIS specification may be for a web map, web scene, REST API, and so on.
Unsupported data from the source JSON. Unsupported JSON is a dictionary of values defined in the ArcGIS specification used to create this object but not currently used in this API. If the object is written back to JSON, any unsupported JSON data is persisted. The ArcGIS specification may be from a web map, web scene, REST API, and so on.
Inherited properties
Defines the properties that allow a layer to be floor-aware. When a layer is configured as floor-aware, it has a FloorAware.floorDefinition property that defines properties that allow a layer to be floor-aware. When it is null (default value) the specific layer does not support floor filtering.
The unique identifying string for the layer, for example specified in a map or scene. The id is used by other parts of this API to refer to a specific Layer, such as in a set of FeatureFenceParameters or a FacilityLayerDefinition. If not supplied, all layers will be assigned a unique id when created.
A flag indicating whether the PopupDefinition defined on the PopupSource is enable / disable. Will return false if an error occurs.
Functions
Clears all selected features.
Clones the FeatureLayer.
Returns a collection of the currently selected features.
Reset the visibility of all features back to their original state.
Reset the renderer back to the original renderer provided by the FeatureTable.
Selects the given feature and adds it to the current collection of selected features. Selected features are rendered according to the GeoView.selectionProperties.
Selects the given features and adds them to the current collection of selected features. Use the FeatureLayer.getSelectedFeatures(): Future
Selects the features that match the criteria in the QueryParameters object and adds them to the current collection of selected features.
Sets the visibility of the given features.
Sets the visibility of the given feature.
Unselects the given feature and removes it from the current collection of selected features.
Unselects the given features and removes them from the current collection of selected features.
Inherited functions
Cancels loading metadata for the Loadable object.
Fetches the list of legend info.
Returns the layer content's effective visibility at the specified scale. Returns the effective layer content visibility. This effective visibility takes care of the effective visibility of the parents at the specified scale. Will return false if an error occurs.