Scopes support for custom constraint validators
by Thang Le
Hi all,
I've come across a scenario which makes me think supporting different
scopes for custom constraint validators would ease the task for writing
efficient validation logic. Similar to Spring IoC, these scopes are
prototype, session & singleton. Currently, the Bean Validation 1.1 spec
suggests a 'prototype' scope should be used for all custom constraint
validation classes. In my opinion, the 'session' (likely singleton as well)
scope proves to be useful when a custom constraint validator needs to do
the SAME timing pre-processing logic before doing some actual validation
logic on the current targeted object. In such cases, the developer would
want to store the result of the pre-processing logic into an instance
variable of the custom constraint validation class and reuse this result
later when the constraint is executed again on different objects. Below is
a specific use-case from my current project.
The model I need to validate has a tree-like structure. In this model, each
node can be a/an remote/access-point/cluster. I have a model builder which
builds the model tree given a set of nodes. The builder then hands off this
tree to the validator to validate it. I have some constraints which require
to check the uniqueness of a certain property for a set of nodes (e.g: all
access-points in the tree must have unique serial number). These
constraints are written as custom constraints. I recognize these
constraints follow the same pattern which is I need to traverse the tree to
collect all required node and build a multimap out of the collected nodes
and check for uniqueness using the key of the current targeted object. For
above example, the custom constraint is a class constraint of access-point
class. I need to collect all access-points in the tree, build a multimap of
<serialNumber:access-point> pairs. Then I lookup from the map the
collection of access-points based on the serial number of the access-point
being validated. It would be beneficial if the multimap of
<serialNumber:access-point> pairs can be stored in the custom validator so
that I don't need to re-do this expensive task again when validating other
access-points.
There might be some reasons that you wouldn't want to support different
scopes for custom constraint validator. However, I would think when it
comes to writing a constraint for a bean in relation with other beans, such
scopes become handy. Please let me know your thoughts on this feature.
Thang
11 years, 4 months
Data-driven execution for validation constraints
by Thang Le
Hi all,
Validation constraints defined in Bean Validation 1.1 are mostly written
and assigned in static manner. This limits us to reuse the existing
constraints in value-driven manner. Could we add a new attribute
'executeCondition' to the constrain definition? 'executeCondition' would
take an EL expression. A bean validation framework would need to evaluate
the expression set in this attribute. The corresponding constraint logic
only gets executed when the expression set for 'executeCondition' is
satisfied at runtime.
Let me know your thoughts on this suggestion.
Thanks,
Thang
11 years, 5 months
Bean Validation fixes
by Emmanuel Bernard
Hello all,
Don't worry, I won't ask for feedback ;)
It's just to let you know that since we are starting to receive minor
fixes requests, we have started to apply them on master.
If a new feature proposal comes, we will create a 1.1 branch for minor
fixes only and leave the master branch for new features (and backported
bug fixes).
The situation has not arisen yet so better not create the branch for
nothing.
Emmanuel
11 years, 5 months
