Databases Reference
In-Depth Information
Reporting Multiple Errors
As you recall from Listing 8.1, the
Validate
method of the
UnleashedObjectContext
class
calls the static
ValidateObject
method of the
Validator
class to validate all new and
modified entity objects. This method throws a
ValidationException
for the first valida-
tion error it encounters. Even though the
Validate
method of the
Order
class might
report two errors at the same time (one for the
OrderDate
and one for the
RequiredDate
properties), only the first one is reported through the exception.
Although reporting a single error at a time might not be a problem in simple pages, like
the Order entry form in the sample application, as the number of fields on the form
increases, fixing one error only to get another is not very user friendly. Figure 8.9 illus-
trates the problem.
FIGURE 8.9
First of multiple errors reported in a Dynamic Data web page.
This is not a problem with the built-in validation attributes such as the
RequiredAttribute
or the
CustomValidationAttribute
applied to individual properties
because they are invoked directly by separate
DynamicValidator
controls inside the field
templates on the web page. In other words, all
property-level
validation attributes are eval-
uated independently, and all errors are reported to the user at the same time. However,
class-level
CustomValidationAttribute
instances and the
Validate
method of the
IValidatableObject
interface are invoked only by the
ValidateObject
method called in
the
SaveChanges
method of the
UnleashedObjectContext
class, and only the first error is
reported.
IDynamicValidatorException Interface
Dynamic Data defines a special interface,
IDynamicValidatorException
, that allows
exception classes to supply information about multiple errors that might have occurred
during a single operation. This interface defines a single property,
InnerExceptions
,
which returns a dictionary of entity property names and exceptions encountered for these
properties.
