/// <summary>
/// Registers the rule with the current <see cref="ModelContext"/>.
/// </summary>
public void Register(ModelType rootType = null)
{
// Determine if the rule is be registered for a specific root model type
if (rootType != null)
{
if (this.rootType != null)
{
throw new InvalidOperationException("Rules cannot be explicitly registered for more than one model type.");
}
this.rootType = rootType;
}
// Raise the Initialization event the first time the rule is registered
if (Initialize != null)
{
Initialize(this, EventArgs.Empty);
Initialize = null;
}
// Default the invocation type to PropertyChanged if none were assigned
if ((int)InvocationTypes == 1)
{
InvocationTypes = RuleInvocationType.PropertyChanged;
}
// Automatically detect predicates if none were specified
if (Predicates == null && ((InvocationTypes & (RuleInvocationType.PropertyChanged | RuleInvocationType.PropertyGet)) > 0))
{
SetPredicates(GetPredicates());
}
// Track and validate uniqueness of condition types
HashSet <ConditionType> conditionTypes = RootType.GetExtension <HashSet <ConditionType> >();
foreach (var conditionType in ConditionTypes)
{
if (conditionTypes.Contains(conditionType))
{
throw new InvalidOperationException("Registered condition types must be unique for each model type: " + conditionType.Code);
}
conditionTypes.Add(conditionType);
}
// Track the rule registration for the root model type
List <Rule> rules = RootType.GetExtension <List <Rule> >();
rules.Add(this);
// Do not perform model type event registration if the rule is not supposed to execute on the server
if ((ExecutionLocation & RuleExecutionLocation.Server) == 0)
{
return;
}
// Init Invocation
if ((InvocationTypes & RuleInvocationType.InitExisting) == RuleInvocationType.InitExisting ||
(InvocationTypes & RuleInvocationType.InitNew) == RuleInvocationType.InitNew)
{
RootType.Init += (sender, e) =>
{
if (((InvocationTypes & RuleInvocationType.InitExisting) == RuleInvocationType.InitExisting && !e.Instance.IsNew) ||
((InvocationTypes & RuleInvocationType.InitNew) == RuleInvocationType.InitNew && e.Instance.IsNew))
{
Invoke(e.Instance, e);
}
};
}
// Property Get Invocation
if ((InvocationTypes & RuleInvocationType.PropertyGet) == RuleInvocationType.PropertyGet)
{
// Subscribe to property get notifications for all return values
RootType.PropertyGet += (sender, e) =>
{
// Determine if the rule is responsible for calculating the property being accessed
if (ReturnValues.Contains(e.Property.Name))
{
// Get the rule manager for the current instance
var manager = e.Instance.GetExtension <RuleManager>();
// Determine if the rule needs to be run
if ((e.IsFirstAccess && (!e.Property.IsPersisted || e.Instance.IsNew || manager.IsPendingInvocation(this))) || manager.IsPendingInvocation(this))
{
// Invoke the rule
Invoke(e.Instance, e);
// Mark the rule state as no longer requiring invocation
manager.SetPendingInvocation(this, false);
}
}
};
if (!InvocationTypes.HasFlag(RuleInvocationType.SuppressPropertyChanged))
{
// Subscribe to property change notifications for all rule predicates
foreach (string predicate in Predicates)
{
RootType.GetPath(predicate).Change += (sender, e) =>
{
// Only invoke the rule if the instance is of the same type as the rule root type
if (RootType.IsInstanceOfType(e.Instance))
{
// Get the rule manager for the current instance
var manager = e.Instance.GetExtension <RuleManager>();
// Mark the rule state as requiring invocation
if (manager.SetPendingInvocation(this, true))
{
// Raise property change notifications
foreach (var property in ReturnValues)
{
e.Instance.Type.Properties[property].NotifyPathChange(e.Instance);
}
}
}
};
}
}
// Mark the properties as calculated to denote that they are return values of a rule
foreach (var property in ReturnValues)
{
var prop = RootType.Properties[property];
if (prop != null)
{
prop.IsCalculated = true;
}
}
}
// Property Change Invocation
if ((InvocationTypes & RuleInvocationType.PropertyChanged) == RuleInvocationType.PropertyChanged)
{
// Subscribe to property change notifications for all rule predicates
foreach (string predicate in Predicates)
{
RootType.GetPath(predicate).Change += (sender, e) =>
{
// Only invoke the rule if the instance is of the same type as the rule root type
if (RootType.IsInstanceOfType(e.Instance))
{
// Get the rule manager for the current instance
var manager = e.Instance.GetExtension <RuleManager>();
// Register the rule to run if it is not already registered
if (manager.SetPendingInvocation(this, true))
{
// Invoke the rule when the last model event scope exits
ModelEventScope.OnExit(() =>
{
// Mark the rule state as no longer requiring invocation
manager.SetPendingInvocation(this, false);
// Invoke the rule
Invoke(e.Instance, e);
});
}
}
};
}
}
// Allow subclasses to perform additional registration logic
OnRegister();
}
