ExpressionInfo

AMD: require(["esri/layers/support/ExpressionInfo"], (ExpressionInfo) => { /* code goes here */ });
ESM: import ExpressionInfo from "@arcgis/core/layers/support/ExpressionInfo.js";
Class: esri/layers/support/ExpressionInfo
Inheritance: ExpressionInfo Accessor
Since: ArcGIS Maps SDK for JavaScript 4.25

The ExpressionInfo class references an Arcade expression following the specification defined by the Arcade Visualization Profile. Expressions must return a string or a number and may access data values from the feature with the $feature profile variable.

This expression is used for defining an AggregateField for use in a FeatureReductionBinning or a FeatureReductionCluster renderer, popup, or label. It is executed once defined inside a layer's featureReduction property.

See also
Example
const expressionInfo = new ExpressionInfo({
  title: "Population per square kilometer",
  returnType: "number",
  expression: "$feature.population / AreaGeodetic($feature, 'square-kilometers')"
});

Constructors

ExpressionInfo

Constructor
new ExpressionInfo(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 Working with Properties topic.
Show inherited properties Hide inherited properties
Name Type Summary Class

The name of the class.

Accessor

An Arcade expression following the specification defined by the Arcade Visualization Profile.

ExpressionInfo

Indicates the return type of the Arcade expression.

ExpressionInfo

The title used to describe the value returned by the expression.

ExpressionInfo

Property Details

declaredClass

Inherited
Property
declaredClass Stringreadonly
Inherited from Accessor

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

expression

Property
expression String

An Arcade expression following the specification defined by the Arcade Visualization Profile. Expressions must return a string or a number and may access data values from the feature with the $feature profile variable.

Example
// Calculates the percentage of the population that is Asian
expressionInfo.expression = "($feature.Asian / $feature.TOT_POP) * 100";

returnType

Property
returnType String

Indicates the return type of the Arcade expression.

Possible Values:"string" |"number"

title

Property
title String

The title used to describe the value returned by the expression.

Example
expressionInfo.title = "Percent Asian";

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.

Accessor
this

Creates a deep clone of this object.

ExpressionInfo
*

Creates a new instance of this class and initializes it with values from a JSON object generated from an ArcGIS product.

ExpressionInfo

Returns true if a named group of handles exist.

Accessor

Removes a group of handles owned by the object.

Accessor

Converts an instance of this class to its ArcGIS portal JSON representation.

ExpressionInfo

Method Details

addHandles

Inherited
Method
addHandles(handleOrHandles, groupKey)
Inherited from Accessor

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(){this}

Creates a deep clone of this object. Any properties that store values by reference will be assigned copies of the referenced values on the cloned instance.

Returns
Type Description
this A deep clone of the class instance that invoked this method.

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

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

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.

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