Data Validations

Validations can be implemented in 2 locations:

• In the data layerLayerLogical separation of functionality within a single system/application, focused on code organization. for simple validations
• In the logic layerLayerLogical separation of functionality within a single system/application, focused on code organization. if the validation also requires access to other Components or other resources

In both layersLayerLogical separation of functionality within a single system/application, focused on code organization., the create and modify methods have the custom-preCreate and custom-preModify anchorsAnchorA marker within generated source code reserved for adding custom logic during re-expansion.. We can use these anchorsAnchorA marker within generated source code reserved for adding custom logic during re-expansion. to validate all incoming values:

StarshipCruds.java

// anchor:custom-preCreate:start
CrudsResult<DataRef> licensePlateValidation = validateLicensePlate(details.getLicensePlate());
if (licensePlateValidation.getLicensePlate()) {
  return licensePlateValidation;
}
// anchor:custom-preCreate:end

// anchor:custom-preModify:start
CrudsResult<DataRef> licensePlateValidation = validateLicensePlate(starshipDetails.getLicensePlate());
if (licensePlateValidation.getLicensePlate()) {
  return licensePlateValidation;
}
// anchor:custom-preModify:end

Now creating an invalid Starship instance or making an invalid change will be rejected before any changes to the database are made.

Error Messages

However, we might also need a clear error message:

CrudsResult<DataRef> error = CrudsResult.error(
  Diagnostic.error("space", "Starship", "space.starship.invalidLicensePlate")
);

Diagnostics represent error messages. They are defined with 3 parameters:

1. component: the name of the component, space in this case
2. element: the name of the element, Starship in this case
3. key: a key that uniquely defines the error message you wish to propagate, the convention is to define it as {component}.{element}.{errorDescription} or {component}.{element}.{field}.{errorDescription}

There are also some helper classes that can be used to create cruds error with error messages.

// DiagnosticFactory can create diagnostics
DiagnosticFactory diagnosticFactory = new DiagnosticFactory("space","starship");
Diagnostic errorMsg = diagnosticFactory.error("space.starship.demoError");

// DiagnosticHelper can create crudsErrors with diagnostics
DiagnosticHelper diagnosticHelper = new DiagnosticHelper("space", "starship");
CrudsResult<DataRef> crudsError = diagnosticHelper.createCrudsError("space.starship.invalidLicensePlate");

// DiagnosticFieldFactory can be used to create diagnostics on field level
DiagnosticFieldFactory fieldFactory = diagnosticFactory.fieldFactory("licensePlate");
Diagnostic fieldErrorMsg = fieldFactory.error("rentWork.car.licensePlate.invalidLicensePlate");

Last, we need to add the translations of the errors to the translation properties files. There are 3 properties files for each Component, which can be found in the Control LayerLayerLogical separation of functionality within a single system/application, focused on code organization.:

• {component}.properties
• {component}_nl.properties
• {component}_en.properties

In these files, there are custom-translations anchorsAnchorA marker within generated source code reserved for adding custom logic during re-expansion. to add any additional translations:

# anchor:custom-translations:start
space.starship.invalidLicensePlate=Not a valid licensePlate
# anchor:custom-translations:end

tip

You can also add additional translation files in the accompanying ext directory.

Options

Option

isRequired Field

Adds a validation that rejects any undefined values for this FieldFieldA property of a DataElement expanded to a database column and user interface input element..

<options>
  <isRequired/>
</options>

Option

validation.listField Field

Rejects any new values for this fieldFieldA property of a DataElement expanded to a database column and user interface input element. that are not listed as a valid TagValuePair.

<options>
  <validation.listField/>
</options>