StreamLayerView

Class: esri/views/layers/StreamLayerView
Inheritance: StreamLayerView LayerView Accessor
Since: ArcGIS Maps SDK for JavaScript 4.4

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.

See also

Property Overview

Any properties can be set, retrieved or listened to. See the Working with Properties topic.
Show inherited properties Hide inherited properties
Name Type Summary Class
Error

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

The status of the Web Socket connection with the stream service.

more details
StreamLayerView
String

The name of the class.

more details
Accessor
FeatureEffect

The featureEffect can be used to draw attention features of interest.

more details
StreamLayerView
FeatureFilter

The attribute, geometry, and time extent filter.

more details
StreamLayerView
Layer

The layer being viewed.

more details
LayerView
Boolean

Indicates if the spatialReference of the MapView is supported by the layer view.

more details
LayerView
Boolean

Value is true if the layer is suspended (i.e., layer will not redraw or update itself when the extent changes).

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LayerView
Boolean

Value is true when the layer is updating; for example, if it is in the process of fetching data.

more details
LayerView
Boolean

When true, the layer is visible in the view.

more details
LayerView

Property Details

connectionError Errorreadonly

The error that explains an unsuccessful attempt to connect to the stream service or an unexpected disconnection from the stream service.

connectionStatus Stringreadonly

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"

declaredClass Stringreadonly inherited
Since: ArcGIS Maps SDK for JavaScript 4.7

The name of the class. The declared class name is formatted as esri.folder.className.

featureEffect FeatureEffectautocast
Since: ArcGIS Maps SDK for JavaScript 4.22

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 by layerView.featureEffect unless the developer overrides it on the layerView. The layerView.featureEffect will take precedence over layer.featureEffect if both properties are set.

Known Limitations

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%)"
});
Since: ArcGIS Maps SDK for JavaScript 4.11

The attribute, geometry, and time extent filter. Only the features that satisfy the filter are displayed on the view.

See also
Example
// display earthquakes that have
// magnitude value of 3 or higher
layerView.filter = new FeatureFilter({
  where: "mag >= 3",
});
layer Layerreadonly inherited

The layer being viewed.

spatialReferenceSupported Booleanreadonly inherited
Since: ArcGIS Maps SDK for JavaScript 4.23

Indicates if the spatialReference of the MapView is supported by the layer view. When false layer view will be suspended.

See also
suspended Booleanreadonly inherited

Value is true if the layer is suspended (i.e., layer will not redraw or update itself when the extent changes).

See also
updating Booleanreadonly inherited

Value is true when the layer is updating; for example, if it is in the process of fetching data.

Default Value:false
visible Boolean inherited

When true, the layer is visible in the view. Value of this property is inherited from the layer.visible unless the developer overrides it. The layerView.visible will take precedence over layer.visible if both properties are set.

Default Value:true

Method Overview

Show inherited methods Hide inherited methods
Name Return Type Summary Class

Adds one or more handles which are to be tied to the lifecycle of the object.

more details
Accessor
Boolean

Emits an event on the instance.

more details
StreamLayerView
Boolean

Indicates whether there is an event listener on the instance that matches the provided event name.

more details
StreamLayerView
Boolean

Returns true if a named group of handles exist.

more details
Accessor
Handle

Highlights the given feature(s).

more details
StreamLayerView
Boolean

isFulfilled() may be used to verify if creating an instance of the class is fulfilled (either resolved or rejected).

more details
LayerView
Boolean

isRejected() may be used to verify if creating an instance of the class is rejected.

more details
LayerView
Boolean

isResolved() may be used to verify if creating an instance of the class is resolved.

more details
LayerView
Object

Registers an event handler on the instance.

more details
StreamLayerView
Promise<object>

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>

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>

Executes a Query against features available for drawing in the layerView and returns a FeatureSet.

more details
StreamLayerView
Promise<FeatureSet>

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.

more details
StreamLayerView
Promise<number[]>

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

Removes a group of handles owned by the object.

more details
Accessor
Promise

when() may be leveraged once an instance of the class is created.

more details
LayerView

Method Details

addHandles(handleOrHandles, groupKey)inherited
Since: ArcGIS Maps SDK for JavaScript 4.25

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.when(
  () => !view.updating,
  () => {
    wkidSelect.disabled = false;
  },
  { once: true }
);

// Handle gets removed when the object is destroyed.
this.addHandles(handle);
Parameters
handleOrHandles WatchHandle|WatchHandle[]

Handles marked for removal once the object is destroyed.

groupKey *
optional

Key identifying the group to which the handles should be added. All the handles in the group can later be removed with Accessor.removeHandles(). If no key is provided the handles are added to a default group.

emit(type, event){Boolean}
Since: ArcGIS Maps SDK for JavaScript 4.5

Emits an event on the instance. This method should only be used when creating subclasses of this class.

Parameters
type String

The name of the event.

event Object
optional

The event payload.

Returns
Type Description
Boolean true if a listener was notified
hasEventListener(type){Boolean}

Indicates whether there is an event listener on the instance that matches the provided event name.

Parameter
type String

The name of the event.

Returns
Type Description
Boolean Returns true if the class supports the input event.
hasHandles(groupKey){Boolean}inherited
Since: ArcGIS Maps SDK for JavaScript 4.25

Returns true if a named group of handles exist.

Parameter
groupKey *
optional

A group key.

Returns
Type Description
Boolean Returns true if a named group of handles exist.
Example
// Remove a named group of handles if they exist.
if (obj.hasHandles("watch-view-updates")) {
  obj.removeHandles("watch-view-updates");
}
highlight(target){Handle}

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.
See also
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);
     });
    }
  });
});
isFulfilled(){Boolean}inherited

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).
isRejected(){Boolean}inherited

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.
isResolved(){Boolean}inherited

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.
on(type, listener){Object}

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 Function

The 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);
});
queryExtent(query, options){Promise<object>}
Since: ArcGIS Maps SDK for JavaScript 4.9

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
query Query autocast
optional
Autocasts from Object

Specifies 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 Object
optional

An object with the following properties.

Specification
signal AbortSignal
optional

Signal 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
      });
    }
  });
});
queryFeatureCount(query, options){Promise<number>}
Since: ArcGIS Maps SDK for JavaScript 4.9

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
query Query autocast
optional
Autocasts from Object

Specifies 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 Object
optional

An object with the following properties.

Specification
signal AbortSignal
optional

Signal 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
});
queryFeatures(query, options){Promise<FeatureSet>}
Since: ArcGIS Maps SDK for JavaScript 4.9

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
query Query autocast
optional
Autocasts from Object

Specifies 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 Object
optional

An object with the following properties.

Specification
signal AbortSignal
optional

Signal 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
      });
    }
  });
});
queryLatestObservations(query, options){Promise<FeatureSet>}
Since: ArcGIS Maps SDK for JavaScript 4.9

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
query Query autocast
optional
Autocasts from Object

Specifies 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 Object
optional

An object with the following properties.

Specification
signal AbortSignal
optional

Signal 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
      });
    }
  });
});
queryObjectIds(query, options){Promise<number[]>}
Since: ArcGIS Maps SDK for JavaScript 4.9

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
query Query autocast
optional
Autocasts from Object

Specifies 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 Object
optional

An object with the following properties.

Specification
signal AbortSignal
optional

Signal 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
});
removeHandles(groupKey)inherited
Since: ArcGIS Maps SDK for JavaScript 4.25

Removes a group of handles owned by the object.

Parameter
groupKey *
optional

A group key or an array or collection of group keys to remove.

Example
obj.removeHandles(); // removes handles from default group

obj.removeHandles("handle-group");
obj.removeHandles("other-handle-group");
when(callback, errback){Promise}inherited
Since: ArcGIS Maps SDK for JavaScript 4.6

when() may be leveraged once an instance of the class is created. This method takes two input parameters: a callback function and an errback function. The callback executes when the instance of the class loads. The errback executes if the instance of the class fails to load.

Parameters
callback Function
optional

The function to call when the promise resolves.

errback Function
optional

The 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}

Fires when the layerView receives data.

more details
StreamLayerView
{client: Number,websocket: Number}

Fires after the layer starts receiving updates from the stream service.

more details
StreamLayerView

Event Details

data-received

Fires when the layerView receives data. The event object contains the message properties received from the stream service.

Properties
attributes Object

Name-value pairs of fields and field values associated with the received data.

geometry Object

A location of the received data containing x, y coordinates for points, paths for lines, and rings for polygons, along with the spatial reference wkid.

update-rate
Since: ArcGIS Maps SDK for JavaScript 4.17

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.

Properties
client Number

The client update rate per second. Returns number of features being processed on the client.

websocket Number

Update rate per second for websocket/service. Returns number of features being pushed from the server.

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