Databases Reference
In-Depth Information
if (!Validator.TryValidateObject(entity, context, results, true))
ThrowValidationException(entity, results);
}
The new version calls the
TryValidateObject
method of the static
Validator
class. Unlike
the
ValidateObject
method used previously, which throws a single
ValidationException
for the
first
error it detects, the
TryValidateObject
method invokes
all
validation attrib-
utes and implementations of the
IValidatableObject
interface. The
TryValidateObject
method collects the errors in the list of
ValidationResult
objects it receives as the third
parameter and returns
false
if any errors were detected.
The
ThrowValidationException
method (shown next) uses the validation results to create
a list of
ValidationException
objects. If multiple validation results were reported, it
throws the
AggregateException
. Otherwise, it throws the
ValidationException
to mimic
the simple behavior implemented earlier:
protected static void ThrowValidationException(
object entity, IEnumerable<ValidationResult> results)
{
var exceptions = new List<ValidationException>();
foreach (ValidationResult result in results)
exceptions.Add(new ValidationException(result, null, entity));
if (exceptions.Count == 1)
throw exceptions[0];
throw new AggregateException(exceptions);
}
NOTE
The
AggregateException
does not inherit from the
ValidationException
class. Now
that the
SaveChanges
method can throw two different exception types, many of the auto-
mated tests written so far will fail because they only expect the
ValidationException
.
To make them pass, change the
ExpectedValidationExceptionAttribute
to support
both types of validation exceptions. You can find the updated implementation of this
attribute in the source code accompanying this topic.
Extending DynamicValidator to Support AggregateException
As discussed in Chapter 3 and Chapter 6, Dynamic Data relies on the
DynamicValidator
control for exception handling. When used in a field template, this control is responsible
for evaluating the validation attributes applied to the entity property the template
instance represents. In field and page templates, this control also handles any exceptions
Entity Framework may throw. Here is the part of this class that implements exception
handling:
