This article explains how to implement handling and validation of common parameter into the Policy Framework Components using .
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Not Spring boot framework
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Environment
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The application should have a ParameterHandler class to support the map values from Json to a POJO, so it should be load the file, convert it performing all type conversion.
The code below shown an example of that class:
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public class PapParameterHandler {
private static final Logger LOGGER = LoggerFactory.getLogger(PapParameterHandler.class);
private static final Coder CODER = new StandardCoder();
/**
* Read the parameters from the parameter file.
*
* @param arguments the arguments passed to policy pap
* @return the parameters read from the configuration file
* @throws PolicyPapException on parameter exceptions
*/
public PapParameterGroup getParameters(final PapCommandLineArguments arguments) throws PolicyPapException {
PapParameterGroup papParameterGroup = null;
// Read the parameters
try {
// Read the parameters from JSON
var file = new File(arguments.getFullConfigurationFilePath());
papParameterGroup = CODER.decode(file, PapParameterGroup.class);
} catch (final CoderException e) {
final String errorMessage = "error reading parameters from \"" + arguments.getConfigurationFilePath()
+ "\"\n" + "(" + e.getClass().getSimpleName() + ")";
throw new PolicyPapException(errorMessage, e);
}
// The JSON processing returns null if there is an empty file
if (papParameterGroup == null) {
final String errorMessage = "no parameters found in \"" + arguments.getConfigurationFilePath() + "\"";
LOGGER.error(errorMessage);
throw new PolicyPapException(errorMessage);
}
// validate the parameters
final ValidationResult validationResult = papParameterGroup.validate();
if (!validationResult.isValid()) {
String returnMessage =
"validation error(s) on parameters from \"" + arguments.getConfigurationFilePath() + "\"\n";
returnMessage += validationResult.getResult();
LOGGER.error(returnMessage);
throw new PolicyPapException(returnMessage);
}
return papParameterGroup;
}
} |
The POJO have to implement org.onap.policy.common.parameters.ParameterGroup interface or eventually extend org.onap.policy.common.parameters.ParameterGroupImpl. The last one already implements validate() method that performs error checking using validation org.onap.policy.common.parameters.annotations.
The code below shown an example of POJO:
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@NotNull
@NotBlank
@Getter
public class PapParameterGroup extends ParameterGroupImpl {
@Valid
private RestServerParameters restServerParameters;
@Valid
private PdpParameters pdpParameters;
@Valid
private PolicyModelsProviderParameters databaseProviderParameters;
private boolean savePdpStatisticsInDb;
@Valid
private TopicParameterGroup topicParameterGroup;
// API, Distribution Health Check REST client parameters.
private List<@NotNull @Valid RestClientParameters> healthCheckRestClientParameters;
/**
* Create the pap parameter group.
*
* @param name the parameter group name
*/
public PapParameterGroup(final String name) {
super(name);
}
} |
Using Spring boot framework
Spring loads automatically the property file and put it available under the org.springframework.core.env.Environment Spring component.
Environment
A component can use Environment component directly.
Environment component is not a good approach because there is not type conversion and error checking, but it could be useful when the name of the property you need to access changes dynamically.
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@Component
@RequiredArgsConstructor
public class Example {
private Environment env;
....
public void method(String pathPropertyName) {
.....
String path = env.getProperty(pathPropertyName);
.....
} |
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A component can use org.springframework.beans.factory.annotation.Value, which reads from properties, performs a type conversion and injects the value into the filed. There is not error checking, but it can assign default value if the property is not defined.
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@Value("${security.enable-csrf:true}")
private boolean csrfEnabled = true; |
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In a scenario that we need to include into a POJO shown before, a class that implement org.onap.policy.common.parameters.ParameterGroup interface, we need to add the org.onap.policy.common.parameters.validation.ParameterGroupConstraint annotation. That annotation is configured to use ParameterGroupValidator that handles the conversion of a org.onap.policy.common.parameters.BeanValidationResult to a Spring validation.
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