arcade

另请参阅

方法概述

名称	返回值类值	描述	对象
	Promise<ArcadeExecutor>	将 Arcade 表达式及其配置文件编译为执行程序。更多详情	arcade
	Profile	为 GeoScene Maps SDK for JavaScript 中实现的 Arcade 配置文件创建配置文件定义。更多详情	arcade

方法详细说明

createArcadeExecutor(script, profile){Promise<ArcadeExecutor>}

将 Arcade 表达式及其配置文件编译为执行程序。执行程序可提供函数来评估配置文件变量的结果。

参数

script String

要编译和执行的 Arcade 表达式。

profile Profile

用于执行给定表达式的配置文件定义。配置文件定义了配置文件变量名称和数据类型，用户可以将其用作表达式中的输入。变量实例提供给执行程序函数。

类型	描述
Promise<ArcadeExecutor>	解析为 ArcadeExecutor，它提供一个同步 (如果适用) 和异步函数，用于在提供有效的输入配置文件变量时计算编译的 Arcade 表达式。

示例

// Synchronous execution for all features in layer view
// % of the population not in labor force
const arcadeScript = "(($feature.POP_16UP - $feature.EMP_CY) / $feature.POP_16UP) * 100"

const profile = {
  variables: [{
    name: "$feature",
    type: "feature"
  }]
};

const laborForceExecutor = await createArcadeExecutor(arcadeScript, profile);
// ensures data values from fields used in the expression are
// available when the expression executes.
layer.outFields = laborForceExecutor.fieldsUsed;

const { features } = await layerView.queryFeatures();

const allValues = features.map( (feature) => {
  return laborForceExecutor.execute({
    "$feature": feature
  });
});

// allValues can be displayed in a chart, or used to
// report stats for this variable

// Asynchronous execution for one feature clicked in the view

const profile = {
  variables: [{
    name: "$feature",
    type: "feature"
  }, {
    name: "$layer",
    type: "featureSet"
  }]
};

// This expression executes on each feature click. It compares the % of the population
// not participating in the labor force with the same value of all features within
// one mile of the selected feature's location
const arcadeScript = `
  var featureNotLaborForce = Round((($feature.POP_16UP - $feature.EMP_CY)/$feature.POP_16UP)*100);
  var id = $feature.OBJECTID;

  var neighbors = Filter( Intersects( $layer, BufferGeodetic($feature, 1, "mile") ), "OBJECTID <> @id" );
  if( Count(neighbors) == 0 ){
    return "No neighbors within 1 mile";
  }

  var neighborsNotLaborForceAverage = Average(neighbors, "( (POP_16UP - EMP_CY) / POP_16UP) * 100");
  var difference = Round(featureNotLaborForce - neighborsNotLaborForceAverage);
  var differenceText = IIF(difference > 0, "+"+difference, Text(difference));
  return differenceText;
`;

const neighborhoodExecutor = await createArcadeExecutor(arcadeScript, profile);
// ensures data values from fields used in the expression are
// available when the expression executes.
layer.outFields = neighborhoodExecutor.fieldsUsed;

view.on("click", async (event) => {
  const hitResponse = await view.hitTest(event, include: { layer });
  const hitGraphic = hitResponse?.results[0].graphic;

  const scriptResult = await neighborhoodExecutor.executeAsync({
    "$feature": hitGraphic,
    "$layer": hitGraphic.layer
  }, {
    spatialReference: view.spatialReference
  });

  // display the value of scriptResult in a UI component or use it
  // in some form of client-side analysis
});

createArcadeProfile(profileName){Profile} 起始版本：GeoScene Maps SDK for JavaScript 4.25

为 GeoScene Maps SDK for JavaScript 中实现的 Arcade 配置文件创建配置文件定义。此操作的结果应提供给 createArcadeExecutor 方法。

参数

profileName String

要创建的 Arcade 配置文件定义的名称。

类型	描述
Profile	返回用于使用 ArcadeExecutor 执行表达式的配置文件定义。

另请参阅

createArcadeExecutor()

示例

const labelingProfile = arcade.createArcadeProfile("labeling");
// creates the following object to be provided to the createArcadeExecutor method.
// {
//   variables: [{
//     name: "$feature",
//     type: "feature"
//   }]
// }

const labelExecutor = await createArcadeExecutor("$feature.NAME + ' COUNTY'", labelingProfile);

类型定义

ArcadeExecutor

该执行程序提供一个同步 (如果适用) 和异步函数，用于使用声明的配置文件变量的输入来计算编译的 Arcade 表达式。它还提供有关编译结果的元数据。

属性

execute ExecuteFunction

可调用的函数，用于评估一组配置文件变量的编译表达式。将返回评估结果。仅当 isAsync 为 false 时，此函数才可用。

executeAsync ExecuteFunctionAsync

计算编译表达式的异步函数。此函数可始终用于评估表达式，但如果 isAsync 为 true，则必须使用此函数。

fieldsUsed String []

使用 $feature 配置变量或需要字段名的函数 (如 Expects) 时，引用编译表达式中使用的字段名。此处引用的字段名应由底层图层或数据存储请求。在 JavaScript 中，这通常使用 layer.outFields 完成。

geometryUsed Boolean

指示表达式是访问还是使用要素的几何。

isAsync Boolean

指示编译后的表达式是否使用 FeatureSet 函数访问数据，因此必须使用 executeAsync 函数执行。如果为 false，则可以使用 execute 或 executeAsync 执行表达式。

另请参阅

createArcadeExecutor

示例

// Synchronous execution for all features in layer view
// % of the population not in labor force
const arcadeScript = "(($feature.POP_16UP - $feature.EMP_CY) / $feature.POP_16UP) * 100"

const profile = {
  variables: [{
    name: "$feature",
    type: "feature"
  }]
};

const laborForceExecutor = await createArcadeExecutor(arcadeScript, profile);
// ensures data values from fields used in the expression are
// available when the expression executes.
layer.outFields = laborForceExecutor.fieldsUsed;

const { features } = await layerView.queryFeatures();

const allValues = features.map( (feature) => {
  return laborForceExecutor.execute({
    "$feature": feature
  });
});

// allValues can be displayed in a chart, or used to
// report stats for this variable

// Asynchronous execution for one feature clicked in the view

const profile = {
  variables: [{
    name: "$feature",
    type: "feature"
  }, {
    name: "$layer",
    type: "featureSet"
  }]
};

// This expression executes on each feature click. It compares the % of the population
// not participating in the labor force with the same value of all features within
// one mile of the selected feature's location
const arcadeScript = `
  var featureNotLaborForce = Round((($feature.POP_16UP - $feature.EMP_CY)/$feature.POP_16UP)*100);
  var id = $feature.OBJECTID;

  var neighbors = Filter( Intersects( $layer, BufferGeodetic($feature, 1, "mile") ), "OBJECTID <> @id" );
  if( Count(neighbors) == 0 ){
    return "No neighbors within 1 mile";
  }

  var neighborsNotLaborForceAverage = Average(neighbors, "( (POP_16UP - EMP_CY) / POP_16UP) * 100");
  var difference = Round(featureNotLaborForce - neighborsNotLaborForceAverage);
  var differenceText = IIF(difference > 0, "+"+difference, Text(difference));
  return differenceText;
`;

const neighborhoodExecutor = await createArcadeExecutor(arcadeScript, profile);
// ensures data values from fields used in the expression are
// available when the expression executes.
layer.outFields = neighborhoodExecutor.fieldsUsed;

view.on("click", async (event) => {
  const hitResponse = await view.hitTest(event, include: { layer });
  const hitGraphic = hitResponse?.results[0].graphic;

  const scriptResult = await neighborhoodExecutor.executeAsync({
    "$feature": hitGraphic,
    "$layer": hitGraphic.layer
  }, {
    spatialReference: view.spatialReference
  });

  // display the value of scriptResult in a UI component or use it
  // in some form of client-side analysis
});

const profile = {
  variables: [{
    name: "$feature",
    type: "feature"
  }]
};

// Arcade expression defined by user...
const syncExecutor = await createArcadeExecutor(arcadeScript, profile);
// ensures data values from fields used in the expression are
// available when the expression executes.
layer.outFields = syncExecutor.fieldsUsed;

// throw error if expression from user uses
// invalid functions that require async execution
if(syncExecutor.isAsync){
  throw new Error("Invalid expression. Expression should not use FeatureSet functions.");
}

const { features } = await layerView.queryFeatures();

const allValues = features.map( (feature) => {
  return syncExecutor.execute({
    "$feature": feature
  });
});

// allValues can be displayed in a chart, or used to
// report stats for this variable

ArrayElementType

array 类型的配置文件变量的类型定义。

属性

type String|String

变量的 Arcade 数据类型。请参阅 ProfileVariableInstanceType 以查看 Arcade 类型到 JavaScript 类型的映射。

properties ProfileVariable []

optional

仅在 type 为 dictionary 时适用。字典属性的类型定义。这些属性的名称不应以 $ 字符开头。

elementType ArrayElementType

optional

仅在 type 为 array 时适用。数组项目的类型定义。当用作输入配置文件变量时，Arcade 数组必须是单一类型。指示 elementType 时，不需要为元素指定名称。

ArrayVariable

Arcade 数组配置文件变量的类型定义。

属性

name String

配置文件变量的名称。为遵循 Arcade 命名约定，这应以 $ 字符开头，除非该变量嵌套在 DictionaryVariable 中。

type String

变量的 Arcade 数据类型。对于 ArrayVariable，类型总是 array。Arcade Array 对应的 JavaScript 类型是遵循 ProfileVariableInstanceType 中定义的规范的数组。

elementType ArrayElementType

optional

数组项目的类型定义。当用作输入配置文件变量时，Arcade 数组必须是单一类型。指示 elementType 时，不需要为元素指定名称。

示例

const profile = {
  variables: [{
    name: "$checkpoints",
    type: "array",
    elementType: {
      type: "feature"
    }
  }]
};

DictionaryVariable

Arcade 字典配置变量的类型定义。

属性

name String

配置文件变量的名称。为遵循 Arcade 命名约定，这应以 $ 字符开头，除非该变量嵌套在另一个 DictionaryVariable 中。请参见下面的示例。

type String

变量的 Arcade 数据类型。Arcade Dictionary 对应的 JavaScript 类型是遵循 ProfileVariableInstanceType 中定义的规范的纯对象。

值通常是 "dictionary"。

properties ProfileVariable []

optional

字典属性的类型定义。这些属性的名称不应以 $ 字符开头。

示例

const profile = {
  variables: [{
    name: "$analysisParams",
    type: "dictionary",
    properties: [{
      name: "distance",
      type: "number"
    }, {
      name: "projectType",
      type: "text"
    }, {
      name: "includeBuffer",
      type: "boolean"
    }]
  }, {
     name: "$projectLocation",
     type: "feature"
  }]
};

ExecuteContext

Arcade 表达式的执行上下文。

属性

spatialReference SpatialReference

optional

几何函数中几何使用的空间参考。

ExecuteFunction(profileVariableInstances, context){ResultType}

与给定的配置文件变量实例同步执行编译的 Arcade 表达式。如果表达式使用 FeatureSet 函数访问数据，则不能使用此函数。

参数

profileVariableInstances Object

键/值对的对象，其中键是创建执行器时定义的 ProfileVariable 的名称。键值类型必须为 ProfileVariableInstanceType。

context ExecuteContext

optional

用于执行表达式的上下文。

类型	描述
ResultType	返回计算表达式的值。

示例

// Synchronous execution for all features in layer view
// % of the population not in labor force
const arcadeScript = "(($feature.POP_16UP - $feature.EMP_CY) / $feature.POP_16UP) * 100"

const profile = {
  variables: [{
    name: "$feature",
    type: "feature"
  }]
};

const laborForceExecutor = await createArcadeExecutor(arcadeScript, profile);
// ensures data values from fields used in the expression are
// available when the expression executes.
layer.outFields = laborForceExecutor.fieldsUsed;

const { features } = await layerView.queryFeatures();

const allValues = features.map( (feature) => {
  return laborForceExecutor.execute({
    "$feature": feature
  });
});

// allValues can be displayed in a chart, or used to
// report stats for this variable

const profile = {
  variables: [{
    name: "$feature",
    type: "feature"
  }]
};

// Arcade expression defined by user...
const syncExecutor = await createArcadeExecutor(arcadeScript, profile);
// ensures data values from fields used in the expression are
// available when the expression executes.
layer.outFields = syncExecutor.fieldsUsed;

// throw error if expression from user uses invalid functions
if(syncExecutor.isAsync){
  throw new Error("Invalid expression. Expression should not use FeatureSet functions.");
}

const { features } = await layerView.queryFeatures();

const allValues = features.map( (feature) => {
  return syncExecutor.execute({
    "$feature": feature
  });
});

// allValues can be displayed in a chart, or used to
// report stats for this variable

ExecuteFunctionAsync(profileVariableInstances, context){Promise<ResultType>}

与给定的配置文件变量实例异步执行编译的 Arcade 表达式。

参数

profileVariableInstances Object

键/值对的对象，其中键是创建执行程序时定义的 ProfileVariable 的名称，其值的类型必须为 ProfileVariableInstanceType。

context ExecuteContext

optional

用于执行表达式的上下文。

类型	描述
Promise<ResultType>	解析为评估表达式的值。

示例

// Asynchronous execution for one feature clicked in the view

const profile = {
  variables: [{
    name: "$feature",
    type: "feature"
  }, {
    name: "$layer",
    type: "featureSet"
  }]
};

// This expression executes on each feature click. It compares the % of the population
// not participating in the labor force with the same value of all features within
// one mile of the selected feature's location
const arcadeScript = `
  var featureNotLaborForce = Round((($feature.POP_16UP - $feature.EMP_CY)/$feature.POP_16UP)*100);
  var id = $feature.OBJECTID;

  var neighbors = Filter( Intersects( $layer, BufferGeodetic($feature, 1, "mile") ), "OBJECTID <> @id" );
  if( Count(neighbors) == 0 ){
    return "No neighbors within 1 mile";
  }

  var neighborsNotLaborForceAverage = Average(neighbors, "( (POP_16UP - EMP_CY) / POP_16UP) * 100");
  var difference = Round(featureNotLaborForce - neighborsNotLaborForceAverage);
  var differenceText = IIF(difference > 0, "+"+difference, Text(difference));
  return differenceText;
`;

const neighborhoodExecutor = await createArcadeExecutor(arcadeScript, profile);
// ensures data values from fields used in the expression are
// available when the expression executes.
layer.outFields = neighborhoodExecutor.fieldsUsed;

view.on("click", async (event) => {
  const hitResponse = await view.hitTest(event, include: { layer });
  const hitGraphic = hitResponse?.results[0].graphic;

  const scriptResult = await neighborhoodExecutor.executeAsync({
    "$feature": hitGraphic,
    "$layer": hitGraphic.layer
  }, {
    spatialReference: view.spatialReference
  });

  // display the value of scriptResult in a UI component or use it
  // in some form of client-side analysis
});

Profile

定义配置文件输入变量的定义。这包括一个对象数组，用于指定每个配置文件变量的名称及其 Arcade 数据类型。所有配置文件名称必须以 $ 字符开头。

属性

variables ProfileVariable []

用作编译表达式输入的配置文件变量的 Arcade 类型定义。

示例

const profile = {
  variables: [{
    name: "$mapClick",
    type: "geometry"
  }, {
    name: "$threshold",
    type: "number"
  }, {
    name: "$feature",
    type: "feature"
  }, {
    name: "$map",
    type: "featureSetCollection"
  }]
};

ProfileVariable SimpleVariable|DictionaryVariable|ArrayVariable

配置文件变量的类型定义。有关更多信息和示例，请参阅各个配置文件变量类型。

使用 ExecuteFunction 或 ExecuteFunctionAsync 评估编译表达式时，可以用作配置文件变量输入的 JavaScript 类型。请参阅下表，了解以下 JavaScript 类型的映射，这些类型可用于为相应的 Arcade 数据类型混合配置文件变量。

Arcade 类型	JS 类型	注
Number	Number
Text	String
Date	Date
Boolean	Boolean
Dictionary	Object	具有键/值对的对象，其中键由 DictionaryVariable 定义，其值必须是 ProfileVariableInstanceType 之一。
Array	Array	Arcade 数组是不可变的，必须是单个 ProfileVariableInstanceType。
Geometry	Geometry
Feature	Graphic
FeatureSet	FeatureLayer \| FeatureSet
FeatureSetCollection	Map \| String	可以提供一个字符串，指向要素服务的 url。

从 Arcade 表达式返回的结果的 JavaScript 类型。

SimpleVariable

简单 Arcade 配置文件变量的类型定义。

属性

name String

配置文件变量的名称。为遵循 Arcade 命名约定，这应以 $ 字符开头，除非该变量嵌套在 DictionaryVariable 中。

type String

变量的 Arcade 数据类型。请参阅 ProfileVariableInstanceType 以查看 Arcade 类型到 JavaScript 类型的映射。

示例

const profile = {
  variables: [{
    name: "$mapClick",
    type: "geometry"
  }, {
    name: "$threshold",
    type: "number"
  }, {
    name: "$feature",
    type: "feature"
  }, {
    name: "$map",
    type: "featureSetCollection"
  }]
};

GeoScene Maps SDK for JavaScript参考手册

方法概述

方法详细说明

类型定义