protected override ValidationResult IsValid(object value, ValidationContext validationContext)
{
var instance = ModelInstance.GetModelInstance(validationContext.ObjectInstance);
var source = new ModelSource(instance.Type, Source);
// Get the member name by looking up using the display name, since the member name is mysteriously null for MVC3 projects
var propertyName = validationContext.MemberName ?? validationContext.ObjectType.GetProperties()
.Where(p => p.GetCustomAttributes(false).OfType <DisplayAttribute>()
.Any(a => a.Name == validationContext.DisplayName)).Select(p => p.Name).FirstOrDefault();
var property = instance.Type.Properties[propertyName];
// Get the list of allowed values
ModelInstanceList allowedValues = source.GetList(instance);
if (allowedValues == null)
{
return(null);
}
// List Property
if (property.IsList)
{
// Get the current property value
ModelInstanceList items = instance.GetList((ModelReferenceProperty)property);
// Determine whether the property value is in the list of allowed values
if (!(items == null || items.All(item => allowedValues.Contains(item))))
{
return(new ValidationResult("Invalid value", new string[] { propertyName }));
}
}
// Reference Property
else
{
// Get the current property value
ModelInstance item = instance.GetReference((ModelReferenceProperty)property);
// Determine whether the property value is in the list of allowed values
if (!(item == null || allowedValues.Contains(item)))
{
return(new ValidationResult("Invalid value", new string[] { propertyName }));
}
}
return(null);
}
IEnumerable <object> GetAllowedValues(ModelInstance root)
{
// Value properties
if (Property is ModelValueProperty)
{
// Get the list of allowed values
IEnumerable instances;
if (modelSource != null)
{
instances = modelSource.GetValue(root) as IEnumerable;
}
else
{
instances = SourceExpression.Invoke(root) as IEnumerable;
}
return(instances != null?instances.Cast <object>().ToArray() : null);
}
// Reference properties
else
{
// Get the model type of the property the rule applies to
ModelType propertyType = ((ModelReferenceProperty)Property).PropertyType;
// Get the list of allowed values
if (modelSource != null)
{
// Model Source
var instances = modelSource.GetList(root);
if (instances != null)
{
return(instances.ToArray());
}
}
else
{
// Model Expression
var instances = SourceExpression.Invoke(root) as IEnumerable;
if (instances != null)
{
return(instances.Cast <object>().Select(i => propertyType.GetModelInstance(i)).ToArray());
}
}
}
return(null);
}
