Expression Property (CIMExpressionInfo)
Gets or sets the Arcade expression used to evaluate and return the value that a property expects.
public string Expression {get; set;}
Public Property Expression As String
Basic Query
//Consult https://github.com/Esri/arcade-expressions/ and
//https://developers.arcgis.com/arcade/ for more examples
//and arcade reference
QueuedTask.Run(() =>
{
//construct an expression
var query = @"Count($layer)";//count of features in "layer"
//construct a CIMExpressionInfo
var arcade_expr = new CIMExpressionInfo()
{
Expression = query.ToString(),
//Return type can be string, numeric, or default
//When set to default, addin is responsible for determining
//the return type
ReturnType = ExpressionReturnType.Default
};
//Construct an evaluator
//select the relevant profile - it must support Pro and it must
//contain any profile variables you are using in your expression.
//Consult: https://developers.arcgis.com/arcade/profiles/
using (var arcade = ArcadeScriptEngine.Instance.CreateEvaluator(
arcade_expr, ArcadeProfile.Popups))
{
//Provision values for any profile variables referenced...
//in our case '$layer'
var variables = new List<KeyValuePair<string, object>>() {
new KeyValuePair<string, object>("$layer", featLayer)
};
//evaluate the expression
try
{
var result = arcade.Evaluate(variables).GetResult();
System.Diagnostics.Debug.WriteLine($"Result: {result.ToString()}");
}
//handle any exceptions
catch (InvalidProfileVariableException ipe)
{
//something wrong with the profile variable specified
//TODO...
}
catch (EvaluationException ee)
{
//something wrong with the query evaluation
//TODO...
}
}
});
Basic Query using Features
//Consult https://github.com/Esri/arcade-expressions/ and
//https://developers.arcgis.com/arcade/ for more examples
//and arcade reference
QueuedTask.Run(() =>
{
//construct an expression
var query = @"$feature.AreaInAcres * 43560.0";//convert acres to ft 2
//construct a CIMExpressionInfo
var arcade_expr = new CIMExpressionInfo()
{
Expression = query.ToString(),
//Return type can be string, numeric, or default
//When set to default, addin is responsible for determining
//the return type
ReturnType = ExpressionReturnType.Default
};
//Construct an evaluator
//select the relevant profile - it must support Pro and it must
//contain any profile variables you are using in your expression.
//Consult: https://developers.arcgis.com/arcade/profiles/
using (var arcade = ArcadeScriptEngine.Instance.CreateEvaluator(
arcade_expr, ArcadeProfile.Popups))
{
//we are evaluating the expression against all features
using (var rc = featLayer.Search())
{
while (rc.MoveNext())
{
//Provision values for any profile variables referenced...
//in our case '$feature'
var variables = new List<KeyValuePair<string, object>>() {
new KeyValuePair<string, object>("$feature", rc.Current)
};
//evaluate the expression (per feature in this case)
try
{
var result = arcade.Evaluate(variables).GetResult();
var val = ((double)result).ToString("0.0#");
System.Diagnostics.Debug.WriteLine(
$"{rc.Current.GetObjectID()} area: {val} ft2");
}
//handle any exceptions
catch (InvalidProfileVariableException ipe)
{
//something wrong with the profile variable specified
//TODO...
}
catch (EvaluationException ee)
{
//something wrong with the query evaluation
//TODO...
}
}
}
}
});
Modify renderer using Arcade
var lyr = MapView.Active.Map.GetLayersAsFlattenedList().OfType<FeatureLayer>().FirstOrDefault(f => f.ShapeType == esriGeometryType.esriGeometryPolygon);
if (lyr == null) return;
QueuedTask.Run(() =>
{
// GetRenderer from Layer (assumes it is a unique value renderer)
var uvRenderer = lyr.GetRenderer() as CIMUniqueValueRenderer;
if (uvRenderer == null) return;
//layer has STATE_NAME field
//community sample Data\Admin\AdminSample.aprx
string expression = "if ($view.scale > 21000000) { return $feature.STATE_NAME } else { return 'All' }";
CIMExpressionInfo updatedExpressionInfo = new CIMExpressionInfo
{
Expression = expression,
Title = "Custom" // can be any string used for UI purpose.
};
//set the renderer's expression
uvRenderer.ValueExpressionInfo = updatedExpressionInfo;
//SetRenderer on Layer
lyr.SetRenderer(uvRenderer);
});
Target Platforms: Windows 11, Windows 10
ArcGIS Pro version: 3 or higher.