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This article explains how to implement handling and validation of common parameter into the Policy Framework Components using .

Not Spring boot framework

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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:

Code Block
language java
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:

Code Block
language java
@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); } }

The code shows below, is an example of Unit Test validation of the POJO PapParameterGroup:

Code Block
language java
private static final Coder coder = new StandardCoder(); @Test void testPapParameterGroup_NullName() throws Exception { String json = commonTestData.getPapParameterGroupAsString(1).replace("\"PapGroup\"", "null"); final PapParameterGroup papParameters = coder.decode(json, PapParameterGroup.class); final ValidationResult validationResult = papParameters.validate(); assertFalse(validationResult.isValid()); assertEquals(null, papParameters.getName()); assertThat(validationResult.getResult()).contains("is null"); }

Using Spring boot framework

Environment

A component can use 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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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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    private ValidatorFactory validatorFactory = Validation.buildDefaultValidatorFactory();

    @Test
    void testParameters_NullTopicParameterGroup() {
        final ClRuntimeParameterGroup parameters = CommonTestData.geParameterGroup();
        parameters.setTopicParameterGroup(null);
        assertThat(validatorFactory.getValidator().validate(parameters)).isNotEmpty();
    }