Predicates
A predicate is a class that defines a condition and segmentation query relating to a specific aspect of a contact - such as preferred language or whether or not they have ever triggered a particular campaign. There is no predicate interface or base class; the combination of a condition and segmentation query makes up a predicate.
Predicates implement the following interfaces:
-
Sitecore.Framework.Rules.IConditiondefines a condition -
Sitecore.XConnect.Segmentation.Predicates.IContactSearchQueryFactorydefines a segmentation query
Context determines whether the condition or segmentation query is used. For example:
-
The List Manager passes the predicate to the segmentation engine, which in turn uses the
IContactSearchQueryFactoryto get a list of matching contacts. -
The Marketing Automation Engine evaluates the
IConditionand uses the result to determine where a contact should move within a plan.
For some predicates it only makes sense to implement ICondition - for example, the logic for “when contact’s e-mail address matches ___________” (Sitecore.XConnect.Segmentation.Predicates.Contacts.EmailAddressMatches) does not lend itself well to a segmentation query, as only one contact will ever be returned.
Sitecore.Rules vs Sitecore.Framework.Rules
Sitecore.Rules and Sitecore.Framework.Rules are two entirely separate implementations of the rules engine and do not overlap. However, both types of conditions are available in the Rules Editor UI. In the following example, the highlighted condition implements ICondition:
Component personalization does not support ICondition. If you want to use the same logic for component personalization and Marketing Automation, you must create an ICondition implementation for Marketing Automation and a RuleCondition<T>whereT:RuleContext implementation for component personalization.
Example: AddressCityMatches
In the following example, the AddressCityMatches implements both IContactSearchQueryFactory and ICondition.
-
In a Marketing Automation context,
Evaluate()returns true or false depending on whether the context contact’s city matches the supplied city. -
In a segmentation context, the
CreateContactSearchQuery()builds an expression that forms part of a segmentation query.
using System;
using System.Linq.Expressions;
using Sitecore.Framework.Rules;
using Sitecore.XConnect.Collection.Model;
namespace Sitecore.XConnect.Segmentation.Predicates.Contacts
{
public class AddressCityMatches : ICondition, IContactSearchQueryFactory
{
public string City { get; set; }
public StringOperationType Comparison { get; set; }
// Used for marketing automation
public bool Evaluate(IRuleExecutionContext context)
{
var contact = context.Fact<Contact>();
return Comparison.Evaluate(contact.Addresses()?.PreferredAddress?.City, City);
}
// Used for segmentation
public Expression<Func<Contact, bool>> CreateContactSearchQuery(IContactSearchQueryContext context)
{
return contact => Comparison.Evaluate(contact.Addresses().PreferredAddress.City, City);
}
}
}