ExternalActionAttribute Class

Assembly: CodeEffects.Rule.Common.dll
Namespace: CodeEffects.Rule.Common.Attributes

Summary

IMPORTANT Generic methods with generic params cannot be used in Source XML as in-rule methods or rule actions. Use plain .Net class(es) if your source object declares generic methods.

When applied to a source object, this attribute references an external qualified public method to be used as a rule action. To qualify, the method must be public, static or instance, return System.Void and either be parameterless or declare only parameters of the source object type or of value types supported by Code Effects.

Syntax

[AttributeUsage(AttributeTargets.Class | AttributeTargets.Interface, AllowMultiple = true, Inherited = true)]
public class ExternalActionAttribute : System.Attribute,
	CodeEffects.Rule.Common.Attributes.IExternalAttribute,
	CodeEffects.Rule.Common.Attributes.ISortable

Properties

Remarks

This attribute is optional and is used to reference external methods that you want to use as rule actions. An exception is thrown if the attribute references a non-qualified method. If the external method defines multiple overloads, decorate each overload that you intend to use as a rule action with the [ActionAttribute](/decision-automation/rule-common-attributes-action), and assign a unique display name to each using its DisplayName property.

Remember that external static or instance action methods can accept your source object as a parameter. When a rule author uses such an action in a rule, parameters of the source object type are not displayed — Rule Editor passes them automatically. In the Rule XML, the parameter of the source object type is represented as this.

The following example illustrates how the rule would appear in Rule Area when a user uses both external actions from the code sample below:

If ID is greater than 10 then Set new ID (0) and Set the Date to UTC

Note that the second method is displayed as parameterless (without parentheses) because it accepts a single parameter of the source type, which is omitted by the editor.

Example

using System;
using CodeEffects.Rule.Common.Attributes;

namespace TestLibrary
{
	// This source object contains no actions of its own
	// but references 2 external actions declared in the Helper class
	[ExternalAction(typeof(Helper), "SetNewDate")]
	[ExternalAction(typeof(Helper), "SetNewID")]
	public class Thing
	{
		public int ID {get; set; } = 0;
		public DateTime? Date { get; set; }
	}

	public class Helper
	{
		[Action("Set new ID", "Sets a new value to the Thing's ID field")]
		public void SetNewID(Thing thing, int id)
		{
			thing.ID = id;
		}

		[Action("Set the Date to UTC", "Sets a new value to the Thing's Date field")]
		public void SetUtcDate(Thing thing)
		{
			thing.Date = DateTime.UtcNow;
		}
	}
}