New features in Web Rule 3.0

using CodeEffects.Rule.Common;
...
public static List<DataSourceItem> GetPhysicians()
{
	List<DataSourceItem> list = new List<DataSourceItem>();
 
	list.Add(new DataSourceItem(1, "John Smith"));
	list.Add(new DataSourceItem(2, "Anna Taylor"));
	list.Add(new DataSourceItem(3, "Robert Brown"));
	list.Add(new DataSourceItem(4, "Stephen Lee"));
	list.Add(new DataSourceItem(5, "Joe Wilson"));
	list.Add(new DataSourceItem(6, "Samuel Thompson"));
 
	return list;
}

function getPhysicians()
{
	var list =
	[
		{ "ID": 1, "Name": "John Smith" },
		{ "ID": 2, "Name": "Anna Taylor" },
		{ "ID": 3, "Name": "Robert Brown" },
		{ "ID": 4, "Name": "Stephen Lee" }
		{ "ID": 5, "Name": "Joe Wilson" }
		{ "ID": 6, "Name": "Samuel Thompson" }
	];
	return list;
};

using CodeEffects.Rule.Attributes;
 
namespace CodeEffects.Rule.Demo.Asp.Common.Data
{
	[Data("Physicians", typeof(Physician), "GetPhysicians")]
	public class Patient
	{
		// C-tor
		public Patient() { }
 
		// This field uses the Physicians dynamic menu source
		[Field(DisplayName = "Primary Care Physician", DataSourceName = "Physicians")]
		public int PhysicianID { get; set; }
	}
}

[Data("Physicians", "getPhysicians")]

[Data("Physicians", typeof(Physician), "GetPhysicians")]

[Data("Physicians", "CodeEffects.Rule.Demo.Asp",
	"CodeEffects.Rule.Demo.Asp.Common.Data.Patient", "GetPhysicians")]

public string TestOne([Parameter(DataSourceName = "Physicians")] int physicianID)
{
	return physicianID.ToString();
}
 
[return: Return(DataSourceName = "Physicians")]
public int TestTwo()
{
	return 1;
}

1. The Dynamic Menu Data Sources feature works only with properties and fields of integral types (int, uint, short, long, etc.) and their nullable equivalents. The value of DataSourceName property will be ignored on properties of all other types. If you think about it, you'll realize that making it work with other types doesn't make any practical sense. Well, with the exception of GUIDs, may be.


2. You data source will be only "semi-dynamic" if you use the server-side .NET methods. In that case the list of menu items will be written in that big chunk of client data that Web Rule adds to your markup. If the list items get updated in the storage, the rule author will see the change only when (s)he refreshes the page (or, to put it more accurately, refreshes that chunk of client data.) But if you use client functions then the freshness of your data only depends on particular implementation of those functions because Web Rule calls them every time the rule author brings up the menu.


3. You have to understand that Web Rule cannot possibly check if a particular value from the data source used to create the rule still exists in that source when it evaluates the rule. Therefore, it is your responsibility as developer to make sure that rules with non-existent values never get evaluated. The Evaluator class throws an exception on such rules.


4. Fields and returns that have data sources use only "is equal to" and "is not equal to" operators. The nullable fields and returns add the "has no value" and "has any value" operators to that list. Again, if you think about it, there is no practical need for any other operators for such fields and returns.


5. If the value of the DataSourceName property of the Field, Return or Parameter attributes is set, all other properties of these attribute classes except for Description and DisplayName will be ignored (no need for them.)

using CodeEffects.Rule.Attributes;
 
namespace CodeEffects.Rule.Demo.Asp.Common.Data
{
	public enum State
	{
		Arizona,
		California,
		Florida,
		Georgia,
		[EnumItem("North Dakota")]
		NorthDakota,
		[EnumItem("South Carolina")]
		SouthCarolina,
		[ExcludeFromEvaluation]
		Unknown
	}
}

1. The Evaluator class now accepts descendant objects.


2. At the time of writing this, removing or clearing the “type” attribute in <rule> node of rule XML tells the typed evaluator (that's the Evaluator<T> class) to bypass checking of the source's type while evaluating the rule against an instance of the source. We will definitely add some kind of a UseAnonimousSourceType property to the Asp.RuleEditor and Mvc.RuleEditor classes in the final version. For now, if you'd like to test this feature, simply remove the “type” attribute from the <rule> node before evaluating your rule.


3. Added a new non-generic Evaluator class that takes a Type of source object as a parameter. Together with the first point, this helps if you create source objects on the fly and don't know their exact types at design time.


4. Added a new DynamicEvaluator class that compiles a given rule (w/o type attribute present) for each source object’s type during evaluation. Keeping count of new Evaluator classes? Yep, there are 3 of them now - the old Evaluator<T>, the non-generic Evaluator and the new DynamicEvaluator. Don't worry, all of this will make perfect sense in just a bit :) All three use the same engine and your existing rule evaluation code won't brake.


5. Properties with the same name but different types in base and descendant source objects no longer generate the “Ambiguous” exception.


6. Added  generic Filter extensions for IQueryable<> that allows pass-thru for LINQ providers, i.e. LINQ-to-SQL and Entity framework. This is huge! Details in a second.


7. Added two new non-generic Filter extensions for IEnumerable and IQueryable. If using this type of filtering, you, the developer, take responsibility for typecasting at run-time.

class ClassA
{
	public int Id;
}
 
class ClassB : ClassA
{
	public string Name { get; set; }
}
 
class ClassC : ClassA
{
	public string Note { get; set; }
}

ClassA a = new ClassA { Id = 1 };
ClassB b = new ClassB { Id = 2, Name = "Test" };
ClassC c = new ClassC { Id = 3, Note = "Some Note" };

//Normally this rule would be created by the RuleEditor class
string rule =
	@"<codeeffects xmlns='http://rule.codeeffects.com/schemas/rule'
		xmlns:ui='http://rule.codeeffects.com/schemas/ui'>
		<rule id='03b33dd0-4389-4ac4-a5aa-bd81fab41eb0' eval='true'
			webrule='3.0.0.87' utc='5/10/2012 4:19:27 PM' type='{0}'>
			<name>et35</name>
			<definition>
				<condition type='equal'>
					<property name='Id' />
					<value type='numeric'>2</value>
				</condition>
			</definition>
		</rule>
	</codeeffects>";

using CodeEffects.Rule.Core;
...
// Here we are saying that this rule was creted for the ClassA class.
rule = string.Format(
	rule, System.Web.HttpUtility.HtmlEncode(typeof(ClassA).AssemblyQualifiedName));
 
Evaluator<ClassA> ev = new Evaluator<ClassA>(rule);
Console.WriteLine(ev.Evaluate(a)); // Produces false
Console.WriteLine(ev.Evaluate(b)); // Produces true
Console.WriteLine(ev.Evaluate(c)); // Produces false

rule = string.Format(rule, "");
 
ev = new Evaluator<ClassA>(rule);
Console.WriteLine(ev.Evaluate(a)); // Produces false
Console.WriteLine(ev.Evaluate(b)); // Produces true
Console.WriteLine(ev.Evaluate(c)); // Produces false

//The rule was created for the ClassA
rule = string.Format(
	rule, System.Web.HttpUtility.HtmlEncode(typeof(ClassA).AssemblyQualifiedName));
 
//The evaluator receives its type from a descendant of the ClassA: ClassB
Evaluator e = new Evaluator(b.GetType(), rule);
 
Console.WriteLine(e.Evaluate(b)); //true

// As before, use the type-agnostic rule XML
rule = string.Format(rule, String.Empty);
 
DynamicEvaluator de = new DynamicEvaluator(rule);
 
Console.WriteLine(de.Evaluate(a)); // Produces false
Console.WriteLine(de.Evaluate(b)); // Produces true
Console.WriteLine(de.Evaluate(c)); // Produces false

class ClassX
{
	public int Id;
}
 
class ClassY : ClassX
{
	public string Id { get; set; }
	public string Name { get; set; }
}

...

ClassX x = new ClassX { Id = 1 };
ClassY y = new ClassY { Id = "2", Name = "Test" };
 
// this rule uses the Id field as a numeric
rule =
       @"<codeeffects xmlns='http://rule.codeeffects.com/schemas/rule'
			xmlns:ui='http://rule.codeeffects.com/schemas/ui'>
			<rule id='03b33dd0-4389-4ac4-a5aa-bd81fab41eb0' eval='true'
				webrule='3.0.0.87' utc='5/10/2012 4:19:27 PM' type=''>
				<name>Test rule</name>
				<definition>
					<condition type='equal'>
						<property name='Id' />
						<value type='numeric'>1</value>
					</condition>
				</definition>
			</rule>
		</codeeffects>";
 
Evaluator evXY = new Evaluator(x.GetType(), rule);
 
Console.WriteLine(evXY.Evaluate(x)); // Produces true
Console.WriteLine(evXY.Evaluate(y)); // Produces false
 
// This rule references the Id field of string type
rule =
@"<codeeffects xmlns='http://rule.codeeffects.com/schemas/rule'
	xmlns:ui='http://rule.codeeffects.com/schemas/ui'>
	<rule id='03b33dd0-4389-4ac4-a5aa-bd81fab41eb0' eval='true'
		webrule='3.0.0.87' utc='5/10/2012 4:19:27 PM' type=''>
		<name>Test rule</name>
		<definition>
			<condition type='equal'>
				<property name='Id' />
				<value type='string'>2</value>
			</condition>
		</definition>
	</rule>
</codeeffects>";
 
evXY = new Evaluator(y.GetType(), rule);
 
Console.WriteLine(evXY.Evaluate(y)); // Produces true

rule =
	@"<codeeffects xmlns='http://rule.codeeffects.com/schemas/rule'
		xmlns:ui='http://rule.codeeffects.com/schemas/rule/ui'>
		<rule id='03b33dd0-4389-4ac4-a5aa-bd81fab41eb0' eval='true'
			webrule='3.0.0.87' utc='5/10/2012 4:19:27 PM' type='{0}'>
			<name>Test rule</name>
			<definition>
				<condition type='greater'>
					<property name='Id' />
					<value type='numeric'>1</value>
				</condition>
			</definition>
		</rule>
	</codeeffects>";
 
rule = string.Format(
	rule, System.Web.HttpUtility.HtmlEncode(typeof(ClassA).AssemblyQualifiedName));
//rule = string.Format(rule, String.Empty);
 
ClassA[] array = new[]
{
       new ClassA { Id = 1 },
       new ClassB { Id = 2, Name = "Test" },
       new ClassB { Id = 3 }
};
 
IEnumerable<ClassA> result = array.Filter(rule);
 
foreach(var item in result)
{
	Console.WriteLine(item.Id);
}
// Produces:
// 2
// 3

var result3 = array.AsQueryable<ClassA>().Filter(rule);
 
Console.WriteLine(result3.ToString());
 
foreach(var item in result3)
{
	Console.WriteLine(item.Id);
}
 
// Produces following output
// YourApplication.ClassA[].Where(x => (x.Id > 1))
// 2
// 3

AdventureWorksDataContext db = new AdventureWorksDataContext();
 
db.Log = Console.Out;
 
string dbrule =
	@"<codeeffects xmlns='http://rule.codeeffects.com/schemas/rule'
		xmlns:ui='http://rule.codeeffects.com/schemas/rule/ui'>
		<rule id='03b33dd0-4389-4ac4-a5aa-bd81fab41eb0' eval='true'
			webrule='3.0.0.87' utc='5/10/2012 4:19:27 PM' type=''>
			<name>Test rule</name>
			<definition>
				<method name='StartsWith' instance='true'>
					<property name='Name' />
					<value type='string'>A</value>
				</method>
			</definition>
		</rule>
	</codeeffects>";
 
var products = db.Products.Filter(dbrule);
 
foreach(var product in products)
{
	Console.WriteLine("{0,3}: {1}", product.ProductID, product.Name);
}
 
/* produces the following ouput
SELECT [t0].[ProductID], [t0].[Name], ...
FROM [Production].[Product] AS [t0]
WHERE [t0].[Name] LIKE @p0
-- @p0: Input NVarChar (Size = 4000; Prec = 0; Scale = 0) [A%]
-- Context: SqlProvider(Sql2008) Model: AttributedMetaModel Build: 4.0.30319.1
 
	1: Adjustable Race
	879: All-Purpose Bike Stand
	712: AWC Logo Cap
*/

dbrule =
	@"<codeeffects xmlns='http://rule.codeeffects.com/schemas/rule'
		xmlns:ui='http://rule.codeeffects.com/schemas/rule/ui'>
		<rule id='03b33dd0-4389-4ac4-a5aa-bd81fab41eb0' eval='true'
			webrule='2.0.0.8' utc='10/20/2011 4:19:27 PM' type=''>
			<name>et35</name>
			<definition>
				<method name='StartsWith' instance='true'>
					<property name='ProductModel.Name' />
					<value type='string'>A</value>
				</method>
			</definition>
		</rule>
	</codeeffects>";
 
var products2 = db.Products.Filter(dbrule);
 
foreach(var product in products2)
{
	Console.WriteLine("{0,3}: {1}", product.ProductID, product.Name);
}
 
/* produces the following ouput:
SELECT [t0].[ProductID], [t0].[Name], ...
FROM [Production].[Product] AS [t0]
LEFT OUTER JOIN [Production].[ProductModel] AS [t1] ON [t1].[ProductModelID] = [t0].[ProductModelID]
WHERE [t1].[Name] LIKE @p0
-- @p0: Input NVarChar (Size = 4000; Prec = 0; Scale = 0) [A%]
-- Context: SqlProvider(Sql2008) Model: AttributedMetaModel Build: 4.0.30319.1
 
879: All-Purpose Bike Stand*/

foreach(var product in products2)
{
	Console.WriteLine("{0,3}: {1} ({2})",
		product.ProductID, product.Name, product.ProductModel.Name);
}
 
/* produces following ouput
SELECT [t0].[ProductID], [t0].[Name], ...
FROM [Production].[Product] AS [t0]
LEFT OUTER JOIN [Production].[ProductModel] AS [t1] ON [t1].[ProductModelID] = [t0].[ProductModelID]
WHERE [t1].[Name] LIKE @p0
-- @p0: Input NVarChar (Size = 4000; Prec = 0; Scale = 0) [A%]
-- Context: SqlProvider(Sql2008) Model: AttributedMetaModel Build: 4.0.30319.1
 
SELECT [t0].[ProductModelID], [t0].[Name], [t0].[CatalogDescription], [t0].[Instructions],
	[t0].[rowguid], [t0].[ModifiedDate]
FROM [Production].[ProductModel] AS [t0]
WHERE [t0].[ProductModelID] = @p0
-- @p0: Input Int (Size = -1; Prec = 0; Scale = 0) [122]
-- Context: SqlProvider(Sql2008) Model: AttributedMetaModel Build: 4.0.30319.1
 
879: All-Purpose Bike Stand (All-Purpose Bike Stand)
*/

var products3 = from product in db.Products
			   select new { product.ProductID, product.Name, product.ProductModel };
 
foreach(var product in products3.Filter(dbrule))
{
	Console.WriteLine("{0,3}: {1} ({2})", product.ProductID, product.Name, product.ProductModel.Name);
}
 
/* produces the following ouput:
SELECT [t0].[ProductID], [t0].[Name], [t2].[test], [t2].[ProductModelID], [t2].[Name] AS [Name2],
	[t2].[CatalogDescription], [t2].[Instructions], [t2].[rowguid], [t2].[ModifiedDate
]
FROM [Production].[Product] AS [t0]
LEFT OUTER JOIN (
	SELECT 1 AS [test], [t1].[ProductModelID], [t1].[Name], [t1].[CatalogDescription],
		[t1].[Instructions], [t1].[rowguid], [t1].[ModifiedDate]
	FROM [Production].[ProductModel] AS [t1]
	) AS [t2] ON [t2].[ProductModelID] = [t0].[ProductModelID]
WHERE [t2].[Name] LIKE @p0
-- @p0: Input NVarChar (Size = 4000; Prec = 0; Scale = 0) [A%]
-- Context: SqlProvider(Sql2008) Model: AttributedMetaModel Build: 4.0.30319.1
 
879: All-Purpose Bike Stand (All-Purpose Bike Stand)
*/

var products4 = from product in db.Products
			   select new { product.ProductID, product.Name, ModelName = product.ProductModel.Name };
 
foreach(var product in products4.Filter(dbrule))
{
	Console.WriteLine("{0,3}: {1} ({2})", product.ProductID, product.Name, product.ModelName);
}

var products5 = from product in db.Products.Filter(dbrule)
			   select new { product.ProductID, product.Name, ModelName = product.ProductModel.Name };
 
foreach(var product in products5)
{
	Console.WriteLine("{0,3}: {1} ({2})", product.ProductID, product.Name, product.ModelName);
}
 
/* produces the following ouput:
SELECT [t0].[ProductID], [t0].[Name], [t1].[Name] AS [ModelName]
FROM [Production].[Product] AS [t0]
LEFT OUTER JOIN [Production].[ProductModel] AS [t1] ON [t1].[ProductModelID] = [t0].[ProductModelID]
WHERE [t1].[Name] LIKE @p0
-- @p0: Input NVarChar (Size = 4000; Prec = 0; Scale = 0) [A%]
-- Context: SqlProvider(Sql2008) Model: AttributedMetaModel Build: 4.0.30319.1
 
879: All-Purpose Bike Stand (All-Purpose Bike Stand) 
*/

System.Collections.IEnumerable result2 = array.Filter(typeof(ClassA), rule);
 
foreach(var item in result2)
{
	Console.WriteLine((item as ClassA).Id);
}
 
// Produces:
// 2
// 3