AggregateField | API Reference | ArcGIS Maps SDK for JavaScript 4.31

Defines the aggregate fields used in a layer visualized with FeatureReductionBinning or FeatureReductionCluster. An aggregate field aggregates data from a layer's field using a statistic type such as the average or sum.

See also

Example

featureReduction.fields = [{
  name: "SUM_population",
  alias: "Total population",
  onStatisticField: "population",
  statisticType: "sum"
}, {
  name: "AVG_age",
  alias: "Average age",
  onStatisticField: "age",
  statisticType: "avg"
}];

Constructors

AggregateField Constructor new AggregateField(properties)

Parameter

properties Object

optional

See the properties for a list of all the properties that may be passed into the constructor.

Property Overview

Any properties can be set, retrieved or listened to. See the Watch for changes topic.

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Type	Summary	Class
String	The display name that describes the aggregate field in the Legend, Popup, and other UI elements.	AggregateField
String	The name of the class.	Accessor
Boolean	Indicates whether the field was created internally by the JS API's rendering engine for default FeatureReductionCluster visualizations.	AggregateField
String	The name of the aggregate field.	AggregateField
ExpressionInfo	An object containing an Arcade expression, which evaluates for each child feature represented by the aggregate graphic.	AggregateField
String	The name of the layer field to summarize with the given statisticType.	AggregateField
String	Defines the type of statistic used to aggregate data returned from onStatisticField or onStatisticExpression.	AggregateField

Property Details

alias Property alias String

The display name that describes the aggregate field in the Legend, Popup, and other UI elements.

Default Value:null

Example

aggregateField.alias = "Total population";

declaredClass Inherited Property declaredClass Stringreadonly Inherited from Accessor

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

isAutoGenerated Property isAutoGenerated Boolean Since: ArcGIS Maps SDK for JavaScript 4.25 AggregateField since 4.24, isAutoGenerated added at 4.25.

Indicates whether the field was created internally by the JS API's rendering engine for default FeatureReductionCluster visualizations. You should avoid setting or changing this value. If true, then all other properties of the AggregateField are read-only.

Default Value:false

name Property name String

The name of the aggregate field. This should describe the layer's field and aggregation method used. For example, if creating a field that contains the total population for a set of features with a population field, then you could name this field total_population or population_sum.

This field name must start with a letter, and may only contain alphanumeric characters and underscore.

Example

// names the aggregate field that will display the sum of the population
// for all points representing cities in the bin
aggregateField.name = "SUM_population";

onStatisticExpression Property onStatisticExpression ExpressionInfo Since: ArcGIS Maps SDK for JavaScript 4.25 AggregateField since 4.24, onStatisticExpression added at 4.25.

An object containing an Arcade expression, which evaluates for each child feature represented by the aggregate graphic. All results of the expression will be aggregated using the given statisticType. This expression must follow the specification defined by the Arcade Visualization Profile. Expressions must return a string or a number and may access data values from the layer's feature with the $feature profile variable.

Example

// will create an aggregate field for the Population field of the layer.
aggregateField.onStatisticExpression = new ExpressionInfo({
  title: "Population per square kilometer",
  returnType: "number",
  expression: "$feature.population / AreaGeodetic($feature, 'square-kilometers')"
});

onStatisticField Property onStatisticField String Since: ArcGIS Maps SDK for JavaScript 4.25 AggregateField since 4.24, onStatisticField added at 4.25.

The name of the layer field to summarize with the given statisticType.

Example

// will create an aggregate field for the Population field of the layer.
aggregateField.onStatisticField = "Population";

statisticType Property statisticType String Since: ArcGIS Maps SDK for JavaScript 4.25 AggregateField since 4.24, statisticType added at 4.25.

Defines the type of statistic used to aggregate data returned from onStatisticField or onStatisticExpression.

Possible Values

Value	Description
`avg`	The average of values in the aggregate. Only available for fields and expressions that return numbers.
`count`	The total number of features in the aggregate. A field does not need to be specified in this case.
`max`	The maximum of all values in the aggregate. Only available for fields and expressions that return numbers.
`min`	The minimum of all values in the aggregate. Only available for fields and expressions that return numbers.
`mode`	The most common or predominant value in the aggregate. Available for fields and expressions that return numbers or strings.
`sum`	The sum of all values in the aggregate. Only available for fields and expressions that return numbers.

Possible Values:"avg" |"count" |"max" |"min" |"mode" |"sum" |"avg_angle"

Example

// will calculate the sum of the field specified in onStatisticField for all features in the bin.
outStatistic.statisticType = "sum";

Method Overview

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Return Type	Summary	Class
	Adds one or more handles which are to be tied to the lifecycle of the object.	Accessor
AggregateField	Creates a deep clone of the AggregateField object.	AggregateField
*	Creates a new instance of this class and initializes it with values from a JSON object generated from an ArcGIS product.	AggregateField
Boolean	Returns true if a named group of handles exist.	Accessor
	Removes a group of handles owned by the object.	Accessor
Object	Converts an instance of this class to its ArcGIS portal JSON representation.	AggregateField

Method Details

addHandles Inherited Method addHandles(handleOrHandles, groupKey) Inherited from Accessor Since: ArcGIS Maps SDK for JavaScript 4.25 Accessor since 4.0, addHandles added at 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 }
);

this.addHandles(handle);

// Destroy the object
this.destroy();

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.

clone Method clone(){AggregateField}

Creates a deep clone of the AggregateField object.

Returns

Type	Description
AggregateField	A deep clone of the object that invoked this method.

Example

// Creates a deep clone of the AggregateField object
const sumPopulationField = layer.featureReduction.fields.find( field => field.name === "SUM_population" ).clone();

fromJSON Method fromJSON(json){*}static

Creates a new instance of this class and initializes it with values from a JSON object generated from an ArcGIS product. The object passed into the input json parameter often comes from a response to a query operation in the REST API or a toJSON() method from another ArcGIS product. See the Using fromJSON() topic in the Guide for details and examples of when and how to use this function.

Parameter

json Object

A JSON representation of the instance in the ArcGIS format. See the ArcGIS REST API documentation for examples of the structure of various input JSON objects.

Returns

Type	Description
*	Returns a new instance of this class.

hasHandles Inherited Method hasHandles(groupKey){Boolean} Inherited from Accessor Since: ArcGIS Maps SDK for JavaScript 4.25 Accessor since 4.0, hasHandles added at 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");
}

removeHandles Inherited Method removeHandles(groupKey) Inherited from Accessor Since: ArcGIS Maps SDK for JavaScript 4.25 Accessor since 4.0, removeHandles added at 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");

toJSON Method toJSON(){Object}

Converts an instance of this class to its ArcGIS portal JSON representation. See the Using fromJSON() guide topic for more information.

Returns

Type	Description
Object	The ArcGIS portal JSON representation of an instance of this class.