StreamLayerView

Property Overview

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 API for JavaScript 4.7

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

effect FeatureEffectautocast

Since: ArcGIS API for JavaScript 4.15

Deprecated since version 4.22. Use featureEffect instead.

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:

• Sample - Apply effects to features

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%)"
};

featureEffect FeatureEffectautocast

Since: ArcGIS API 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

• 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:

• StreamLayer.featureEffect

• Sample - Apply effects to features

• Sample - Apply drop-shadow effect to a layerView

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%)"
});

filter FeatureFilterautocast

Since: ArcGIS API 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:

• Sample - Filter features by attributes

• Sample - Filter features by geometry

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.

suspended Booleanreadonly inherited

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

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

Method Details

emit(type, event){Boolean}

Since: ArcGIS API 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.

highlight(target){Handle}

Highlights the given feature(s).

Parameter:

target Graphic|Graphic[]|Number|Number[] 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:

• SceneView.highlightOptions

• Sample: Highlight point features

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:

type String|String[] 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 API 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 API 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){
    watchUtils.whenNotOnce(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 API 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 API 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 API 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){
    watchUtils.whenNotOnce(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
});

when(callback, errback){Promise}inherited

Since: ArcGIS API 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

{attributes: Object,geometry: Object}

{client: Number,websocket: Number}

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 and the spatial reference wkid.

update-rate

Since: ArcGIS API 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.