Represents the LayerView of a StreamLayer after it has been added to a Map in either a MapView or SceneView.
The StreamLayerView is responsible for rendering a StreamLayer's features as graphics in the View. The methods in the StreamLayerView provide developers with the ability to query and highlight graphics in the view. See the code snippets in the methods below for examples of how to access client-side graphics from the view.
It connects to a server that emits geographic features continuously. The stream layer is suitable when you would like to map dynamic streams of data that are unbounded and continuous. When a StreamLayer is added to a map, users are able to see any real-time updates pushed out by the server. For more information, read the documentation of StreamLayer.
Property Overview
Name | Type | Summary | Class | |
---|---|---|---|---|
Error | more details The error that explains an unsuccessful attempt to connect to the stream service or an unexpected disconnection from the stream service. | more details | StreamLayerView | |
String | more details The status of the Web Socket connection with the stream service. | more details | StreamLayerView | |
String | more details The name of the class. | more details | Accessor | |
FeatureEffect | more details The effect applied to the layerView. | more details | StreamLayerView | |
FeatureEffect | more details The featureEffect can be used to draw attention features of interest. | more details | StreamLayerView | |
FeatureFilter | more details The attribute, geometry, and time extent filter. | more details | StreamLayerView | |
Layer | more details The layer being viewed. | more details | LayerView | |
Boolean | more details Indicates if the spatialReference of the MapView is supported by the layer view. | more details | LayerView | |
Boolean | more details Value is | more details | LayerView | |
Boolean | more details Value is | more details | LayerView | |
Boolean | more details When | more details | LayerView |
Property Details
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connectionError Errorreadonly
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The error that explains an unsuccessful attempt to connect to the stream service or an unexpected disconnection from the stream service.
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connectionStatus Stringreadonly
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The status of the Web Socket connection with the stream service. This property can be watched to see if the connection is lost unexpectedly.
Possible Values:"connected"|"disconnected"
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Since: ArcGIS API for JavaScript 4.7
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The name of the class. The declared class name is formatted as
esri.folder.className
.
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effect FeatureEffectautocastSince: ArcGIS API for JavaScript 4.15Deprecated since version 4.22. Use featureEffect instead.
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The effect applied to the layerView. The effect allows for the selection of features via a filter, and an includedEffect and excludedEffect are applied to those features that respectively pass or fail the filter requirements.
Known Limitations
FeatureEffect is not supported in 3D SceneViews.
- See also:
Example:// set effect on excluded features (if outside of the geometry) // make them gray and transparent streamLayerView.effect = { filter: { // autocasts to FeatureFilter geometry: areaOfInterest, }, excludedEffect: "grayscale(100%) opacity(30%)" };
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featureEffect FeatureEffectautocastSince: ArcGIS API for JavaScript 4.22
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The featureEffect can be used to draw attention features of interest. It allows for the selection of features via a filter, and an includedEffect and excludedEffect are applied to those features that respectively pass or fail the filter requirements.
If the
featureEffect
is set on the layer, it will be inherited bylayerView.featureEffect
unless the developer overrides it on the layerView. ThelayerView.featureEffect
will take precedence overlayer.featureEffect
if both properties are set.Known Limitations
- FeatureEffect is not supported in the following scenarios:
- In 3D SceneViews
- In a layer rendered with a HeatmapRenderer
- When FeatureReductionCluster is enabled
- When a map is printed
- A FeatureEffect set on a layerView cannot persisted in a WebMap.
- See also:
Examples:// gray out features that fall outside of the 3 mile buffer of the mouse's location // by setting feature effect on excluded features layerView.featureEffect = new FeatureEffect({ filter: new FeatureFilter({ geometry: filterGeometry, spatialRelationship: "intersects", distance: 3, units: "miles" }), excludedEffect: "grayscale(100%) opacity(30%)" });
// Apply a drop-shadow feature effect to the features that intersect the borough boundaries, // while applying blur and brightness effects to the features that are excluded from filter criteria. // The resulting map will make it easier to spot if the residents are more likely to experience deprivation // if they live on a borough boundary. const featureFilter = new FeatureFilter({ where: "BoroughEdge='true'" }); layerView.featureEffect = new FeatureEffect({ filter: featureFilter, includedEffect: "drop-shadow(3px, 3px, 3px, black)", excludedEffect: "blur(1px) brightness(65%)" });
- FeatureEffect is not supported in the following scenarios:
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filter FeatureFilterautocastSince: ArcGIS API for JavaScript 4.11
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The attribute, geometry, and time extent filter. Only the features that satisfy the filter are displayed on the view.
Example:// display earthquakes that have // magnitude value of 3 or higher layerView.filter = new FeatureFilter({ where: "mag >= 3", });
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The layer being viewed.
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Since: ArcGIS API for JavaScript 4.23
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Indicates if the spatialReference of the MapView is supported by the layer view. When
false
layer view will be suspended.- See also:
-
Value is
true
if the layer is suspended (i.e., layer will not redraw or update itself when the extent changes).- See also:
-
Value is
true
when the layer is updating; for example, if it is in the process of fetching data.- Default Value:false
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When
true
, the layer is visible in the view. Value of this property is inherited from thelayer.visible
unless the developer overrides it. ThelayerView.visible
will take precedence overlayer.visible
if both properties are set.- Default Value:true
Method Overview
Name | Return Type | Summary | Class | |
---|---|---|---|---|
Boolean | more details Emits an event on the instance. | more details | StreamLayerView | |
Boolean | more details Indicates whether there is an event listener on the instance that matches the provided event name. | more details | StreamLayerView | |
Handle | more details Highlights the given feature(s). | more details | StreamLayerView | |
Boolean | more details
| more details | LayerView | |
Boolean | more details
| more details | LayerView | |
Boolean | more details
| more details | LayerView | |
Object | more details Registers an event handler on the instance. | more details | StreamLayerView | |
more details Adds one or more handles which are to be tied to the lifecycle of the object. | more details | Accessor | ||
Promise<Object> | more details Executes a Query against features available for drawing in the layerView and returns the Extent of features that satisfy the query. | more details | StreamLayerView | |
Promise<Number> | more details Executes a Query against features available for drawing in the layerView and returns the number of features that satisfy the query. | more details | StreamLayerView | |
Promise<FeatureSet> | more details Executes a Query against features available for drawing in the layerView and returns a FeatureSet. | more details | StreamLayerView | |
Promise<FeatureSet> | more details If a trackIdField is specified on the stream service, this method executes a Query against features available for drawing in the layerView and returns a FeatureSet of the latest observations for each | more details | StreamLayerView | |
Promise<Number[]> | more details Executes a Query against features available for drawing in the layerView and returns array of the ObjectIDs of features that satisfy the input query. | more details | StreamLayerView | |
Promise | more details
| more details | LayerView |
Method Details
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emit(type, event){Boolean}Since: ArcGIS API for JavaScript 4.5
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Emits an event on the instance. This method should only be used when creating subclasses of this class.
Parameters:type StringThe name of the event.
event ObjectoptionalThe event payload.
Returns:Type Description Boolean true
if a listener was notified
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hasEventListener(type){Boolean}
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Indicates whether there is an event listener on the instance that matches the provided event name.
Parameter:type StringThe name of the event.
Returns:Type Description Boolean Returns true if the class supports the input event.
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highlight(target){Handle}
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Highlights the given feature(s).
Parameter:optional The feature(s) to highlight. When passing a graphic or array of graphics, each feature must have a valid
objectID
. You may alternatively pass one or more objectIDs as a single number or an array.Returns:Type Description Handle Returns a highlight handler with a remove()
method that can be called to remove the highlight.Example:// highlight feature on pointer-move view.on("pointer-move", function(event){ view.hitTest(event).then(function(response){ if (response.results.length) { let graphic = response.results.filter(function (result) { return result.graphic.layer === myLayer; })[0].graphic; view.whenLayerView(graphic.layer).then(function(layerView){ layerView.highlight(graphic); }); } }); });
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isFulfilled()
may be used to verify if creating an instance of the class is fulfilled (either resolved or rejected). If it is fulfilled,true
will be returned.Returns:Type Description Boolean Indicates whether creating an instance of the class has been fulfilled (either resolved or rejected).
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isRejected()
may be used to verify if creating an instance of the class is rejected. If it is rejected,true
will be returned.Returns:Type Description Boolean Indicates whether creating an instance of the class has been rejected.
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isResolved()
may be used to verify if creating an instance of the class is resolved. If it is resolved,true
will be returned.Returns:Type Description Boolean Indicates whether creating an instance of the class has been resolved.
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on(type, listener){Object}
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Registers an event handler on the instance. Call this method to hook an event with a listener.
Parameters:An event or an array of events to listen for.
listener FunctionThe function to call when the event fires.
Returns:Type Description Object Returns an event handler with a remove()
method that should be called to stop listening for the event(s).Property Type Description remove Function When called, removes the listener from the event. Example:view.on("click", function(event){ // event is the event handle returned after the event fires. console.log(event.mapPoint); });
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own(handleOrHandles)inheritedSince: ArcGIS API for JavaScript 4.24
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Adds one or more handles which are to be tied to the lifecycle of the object. The handles will be removed when the object is destroyed.
// Manually manage handles const handle = reactiveUtils.whenOnce(() => !view.updating) .then(() => { wkidSelect.disabled = false; }); handle.remove(); // Assign a handle using own() this.own(reactiveUtils.whenOnce(() => !view.updating) .then(() => { wkidSelect.disabled = false; }));
Parameter:handleOrHandles WatchHandle|WatchHandle[]Handles marked for removal once the object is destroyed.
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Since: ArcGIS API for JavaScript 4.9
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Executes a Query against features available for drawing in the layerView and returns the Extent of features that satisfy the query. If query parameters are not provided, the extent and count of all features available for drawing are returned.
Known Limitations
- Spatial queries have the same limitations as those listed in the projection engine documentation.
- Spatial queries are not currently supported if the layerView has any of the following SpatialReferences:
- GDM 2000 (4742) – Malaysia
- Gusterberg (Ferro) (8042) – Austria/Czech Republic
- ISN2016 (8086) - Iceland
- SVY21 (4757) - Singapore
Parameters:optional Autocasts from ObjectSpecifies the attributes, spatial, and temporal filter of the query. When no parameters are passed to this method, all features in the client are returned. To only return features visible in the view, set the
geometry
parameter in the query object to the view's extent.options ObjectoptionalAn object with the following properties.
Specification:signal AbortSignaloptionalSignal object that can be used to abort the asynchronous task. The returned promise will be rejected with an Error named
AbortError
when an abort is signaled. See also AbortController for more information on how to construct a controller that can be used to deliver abort signals.Returns:Type Description Promise<Object> When resolved, returns the extent and count of the features that satisfy the input query. See the object specification table below for details. Property Type Description count Number The number of features that satisfy the input query. extent Extent The extent of the features that satisfy the query. Example:let layer = new StreamLayer({ url: streamLayerUrl // URL to a stream service }); view.whenLayerView(layer).then(function(layerView){ layerView.watch("updating", function(val){ if(!val){ // wait for the layerView to finish updating layerView.queryExtent().then(function(results){ view.goTo(results.extent); // go to the extent of all the graphics in the layerView }); } }); });
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Since: ArcGIS API for JavaScript 4.9
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Executes a Query against features available for drawing in the layerView and returns the number of features that satisfy the query. If query parameters are not provided, the count of all features available for drawing is returned.
Known Limitations
- Spatial queries have the same limitations as those listed in the projection engine documentation.
- Spatial queries are not currently supported if the layerView has any of the following SpatialReferences:
- GDM 2000 (4742) – Malaysia
- Gusterberg (Ferro) (8042) – Austria/Czech Republic
- ISN2016 (8086) - Iceland
- SVY21 (4757) - Singapore
Parameters:optional Autocasts from ObjectSpecifies the attributes, spatial, and temporal filter of the query. When no parameters are passed to this method, all features in the client are returned. To only return features visible in the view, set the
geometry
parameter in the query object to the view's extent.options ObjectoptionalAn object with the following properties.
Specification:signal AbortSignaloptionalSignal object that can be used to abort the asynchronous task. The returned promise will be rejected with an Error named
AbortError
when an abort is signaled. See also AbortController for more information on how to construct a controller that can be used to deliver abort signals.Returns:Type Description Promise<Number> When resolved, returns the number of features satisfying the query. Examples:view.on("click", function(event){ let query = new Query(); query.geometry = event.mapPoint; // obtained from a view click event query.spatialRelationship = "intersects"; view.whenLayerView(layer).then(function(layerView){ reactiveUtils.whenOnce(() => !layerView.updating) .then(function(){ return layerView.queryFeatureCount(query); }) .then(function(count){ console.log(count); // prints the number of the client-side graphics that satisfy the query }); }); });
view.whenLayerView(layer).then(function(layerView){ return layerView.queryFeatureCount() }).then(function(count){ console.log(count); // prints the total number of client-side graphics to the console });
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queryFeatures(query, options){Promise<FeatureSet>}Since: ArcGIS API for JavaScript 4.9
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Executes a Query against features available for drawing in the layerView and returns a FeatureSet. If query parameters are not provided, all features available for drawing are returned.
Known Limitations
- Spatial queries have the same limitations as those listed in the projection engine documentation.
- Spatial queries are not currently supported if the layerView has any of the following SpatialReferences:
- GDM 2000 (4742) – Malaysia
- Gusterberg (Ferro) (8042) – Austria/Czech Republic
- ISN2016 (8086) - Iceland
- SVY21 (4757) - Singapore
Parameters:optional Autocasts from ObjectSpecifies the attributes, spatial, and temporal filter of the query. When no parameters are passed to this method, all features in the client are returned. To only return features visible in the view, set the
geometry
parameter in the query object to the view's extent.options ObjectoptionalAn object with the following properties.
Specification:signal AbortSignaloptionalSignal object that can be used to abort the asynchronous task. The returned promise will be rejected with an Error named
AbortError
when an abort is signaled. See also AbortController for more information on how to construct a controller that can be used to deliver abort signals.Returns:Type Description Promise<FeatureSet> When resolved, a FeatureSet containing an array of graphic features is returned. Examples:view.whenLayerView(layer).then(function(layerView){ layerView.watch("updating", function(val){ if(!val){ // wait for the layerView to finish updating layerView.queryFeatures(query).then(function(results){ console.log(results.features); // prints the array of client-side graphics to the console }); } }); });
// returns all the graphics from the layerView view.whenLayerView(layer).then(function(layerView){ layerView.watch("updating", function(val){ if(!val){ // wait for the layerView to finish updating layerView.queryFeatures().then(function(results){ console.log(results.features); // prints all the client-side graphics to the console }); } }); });
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queryLatestObservations(query, options){Promise<FeatureSet>}Since: ArcGIS API for JavaScript 4.9
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If a trackIdField is specified on the stream service, this method executes a Query against features available for drawing in the layerView and returns a FeatureSet of the latest observations for each
trackId
that satisfy the query. Otherwise, an Error will be thrown when the method is called.Known Limitations
- Spatial queries have the same limitations as those listed in the projection engine documentation.
- Spatial queries are not currently supported if the layerView has any of the following SpatialReferences:
- GDM 2000 (4742) – Malaysia
- Gusterberg (Ferro) (8042) – Austria/Czech Republic
- ISN2016 (8086) - Iceland
- SVY21 (4757) - Singapore
Parameters:optional Autocasts from ObjectSpecifies the attributes, spatial, and temporal filter of the query. When no parameters are passed to this method, all features in the client are returned. To only return features visible in the view, set the
geometry
parameter in the query object to the view's extent.options ObjectoptionalAn object with the following properties.
Specification:signal AbortSignaloptionalSignal object that can be used to abort the asynchronous task. The returned promise will be rejected with an Error named
AbortError
when an abort is signaled. See also AbortController for more information on how to construct a controller that can be used to deliver abort signals.Returns:Type Description Promise<FeatureSet> When resolved, returns the FeatureSet that satisfy the input query. Example:let layer = new StreamLayer({ url: streamLayerUrl // URL to a Stream Service }); view.whenLayerView(layer).then(function(layerView){ layerView.watch("updating", function(val){ if(!val){ // wait for the layerView to finish updating layerView.queryLatestObservations().then(function(results){ console.log(results.features); // prints all the client-side graphics to the console }); } }); });
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Since: ArcGIS API for JavaScript 4.9
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Executes a Query against features available for drawing in the layerView and returns array of the ObjectIDs of features that satisfy the input query. If query parameters are not provided, the ObjectIDs of all features available for drawing are returned.
Known Limitations
- Spatial queries have the same limitations as those listed in the projection engine documentation.
- Spatial queries are not currently supported if the layerView has any of the following SpatialReferences:
- GDM 2000 (4742) – Malaysia
- Gusterberg (Ferro) (8042) – Austria/Czech Republic
- ISN2016 (8086) - Iceland
- SVY21 (4757) - Singapore
Parameters:optional Autocasts from ObjectSpecifies the attributes, spatial, and temporal filter of the query. When no parameters are passed to this method, all features in the client are returned. To only return features visible in the view, set the
geometry
parameter in the query object to the view's extent.options ObjectoptionalAn object with the following properties.
Specification:signal AbortSignaloptionalSignal object that can be used to abort the asynchronous task. The returned promise will be rejected with an Error named
AbortError
when an abort is signaled. See also AbortController for more information on how to construct a controller that can be used to deliver abort signals.Returns:Type Description Promise<Number[]> When resolved, returns an array of numbers representing the ObjectIDs of the features satisfying the query. Examples:view.on("click", function(event){ let query = new Query(); query.geometry = event.mapPoint; // obtained from a view click event query.spatialRelationship = "intersects"; view.whenLayerView(layer).then(function(layerView){ reactiveUtils.whenOnce(() => !layerView.updating) .then(function(){ return layerView.queryObjectIds(query); }) .then(function(ids){ console.log(ids); // prints the ids of the client-side graphics to the console }); }); });
// returns all the Ids from the graphics in the layerView view.whenLayerView(layer).then(function(layerView){ return layerView.queryObjectIds() }).then(function(ids){ console.log(ids); // prints the ids of all the client-side graphics to the console });
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Since: ArcGIS API for JavaScript 4.6
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when()
may be leveraged once an instance of the class is created. This method takes two input parameters: acallback
function and anerrback
function. Thecallback
executes when the instance of the class loads. Theerrback
executes if the instance of the class fails to load.Parameters:callback FunctionoptionalThe function to call when the promise resolves.
errback FunctionoptionalThe function to execute when the promise fails.
Returns:Type Description Promise Returns a new promise for the result of callback
that may be used to chain additional functions.Example:// Although this example uses MapView, any class instance that is a promise may use when() in the same way let view = new MapView(); view.when(function(){ // This function will execute once the promise is resolved }, function(error){ // This function will execute if the promise is rejected due to an error });
Event Overview
Name | Type | Summary | Class | |
---|---|---|---|---|
{attributes: Object,geometry: Object} |
more details
Fires when the layerView receives data. |
more details | StreamLayerView | |
{client: Number,websocket: Number} |
more details
Fires after the layer starts receiving updates from the stream service. |
more details | StreamLayerView |
Event Details
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data-received
-
Fires when the layerView receives data. The event object contains the message properties received from the stream service.
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update-rateSince: ArcGIS API for JavaScript 4.17
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Fires after the layer starts receiving updates from the stream service. It will return the websocket and the client update rates per second. The update rate indicates number of features are being pushed from the server and being processed on the client side. The client update rate will be approximately equal to the websocket update rate unless the service is pushing updates at a rate faster than the client can handle. In which case, the API will down-throttle the update rate and will cause the client update rate to be lower.