Backend Bean Validation How-to

Adding validation on beans used in the backend is easy and should be adopted by everyone. Using the jsr 303 and its Jboss reference implementation hibernate validator, the work is really clean and quick.

Where is it used currently in

To validate the command inputs parameters classes i.e. all the descendants of VdcActionParametersBase and the beans they are composed from. The validation is fits into the execution before CanDoAction phase:

  Authorization check 
         |
          -> Backward Compatibility check
                       |
                        -> *Validate Inputs*
                                |
                                 -> Can do action

How to annotate my command inputs

Basic Usage

lets look at existing validation of a hot plugging a disk to a VM. The command involved is ` HotPlugDiskToVM ` which uses ` HotPlugDiskToVmParameter ` and we want to validate to target ` diskId ` will never be null.

the required constraint annotation is:

  public class HotPlugDiskToVmParameters extends VmDiskOperatinParameterBase {
     @NotNull
     private Guid diskId;

that’s it. The rest is done by ` CommandBase.validateInputs() ` !

complex hierarchy validation - @Valid

if you need to validate a member inside an object passed:

  class VmManagementParameterBase
  @Valid
  private VmStatic vmStatic

and in VmStatic class

  class VmStatic
  @Size(min = 1)
  private Name name;

Control when to use a validation - Validation Groups

An annotated parameter class could be shared by one or more Commands thus the validation proposed by the annotation doesn’t necessarily fit into all.

example: we need to validate storage_domain_static name when its passed in a parameter class for adding storage or updating it. Other Commands that has it in their params should ignore those validation constraints.

To achieve that we use Validation Groups. Its a marker interface passed to the validator and make it look only for validation marked with those interfaces.

1st annotate and specify a new marker interface in ` groups `

   class StorageDomainManagementParameter extends StorageDomainParametersBase {
     @Valid
     private storage_domain_static privateStorageDomain;
  ...
   @ValidName(message = "VALIDATION.STORAGE_DOMAIN.NAME.INVALID", groups = { CreateEntity.class, UpdateEntity.class })
   private String name = "";

The marker interface:

  import javax.validation.groups.Default;
  public interface CreateEntity extends Default { }
   

now state what validation groups your command needs by invoking addValidationGroups or overriding addValidationGroup method

  class CreateFooEntityCommand {
  public CreateFooEntityCommand() {
      addValidationGroup(CreateEntity.class);

or

  @Override
     protected List`<Class<?>`> getValidationGroups() {
         return addValidationGroup(CreateEntity.class);
     }

Custom canDoMessages in validations

  @NotNull(message = "VALIDATION_NULL_VM_GUID"
  private Guid vmId

  AppErrors.properties:
  VALIDATION_NULL_VM_GUID=Null VM id is prohibited here.

Further readings

Read on the built-in constrains you can use.

Read on how to create your own custom constraints