ExpressionInfo

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

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.
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Name Type Summary Class
String

The name of the class.

more details
Accessor
String

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

more details
ExpressionInfo
String

Indicates the return type of the Arcade expression.

more details
ExpressionInfo
String

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

more details
ExpressionInfo

Property Details

declaredClass Stringreadonly inherited

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

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.

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

Indicates the return type of the Arcade expression.

Possible Values:"string"|"number"

title String

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

Example
expressionInfo.title = "Percent Asian";

Method Overview

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Name Return Type Summary Class

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

more details
Accessor
this

Creates a deep clone of this object.

more details
ExpressionInfo
*

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

more details
ExpressionInfo
Boolean

Returns true if a named group of handles exist.

more details
Accessor

Removes a group of handles owned by the object.

more details
Accessor
Object

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

more details
ExpressionInfo

Method Details

addHandles(handleOrHandles, groupKey)inherited

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.

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(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(groupKey){Boolean}inherited

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(groupKey)inherited

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(){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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