Custom Snap

[ashlam]

I can’t able to get the values from previous snap.I used mapper to set a value and retrieve using expression from previous snap but getting error alike cannot set null value.

@General(title = “Example snap”, purpose = “”, author = “”)
@Category(snap = SnapCategory.READ)
@Version(snap = 1)
@Inputs(min = 1, max = 1, accepts = { ViewType.DOCUMENT })
@Outputs(min = 1, max = 1, offers = { ViewType.DOCUMENT })
@Errors(min = 1, max = 1, offers = { ViewType.DOCUMENT })
public class ExampleSnap implements Snap
{

private static final String CACHE_DATA_ID = "Key";


private String Key;
private String valueCategory;



@Inject
private DocumentUtility documentUtility;

@Inject
private InputViews inputViews;
@Inject
private OutputViews outputViews;
@Inject
private ErrorViews errorViews;

@Override
public void defineProperties(final PropertyBuilder propBuilder)
{
	
	propBuilder.describe(CACHE_DATA_ID, CACHE_DATA_ID).expression().schemaAware(SnapProperty.DecoratorType.ACCEPTS_SCHEMA)
			.add();


}

@Override
public void configure(PropertyValues propertyValues) throws ConfigurationException
{
		valueCategory = propertyValues.getAsExpression(CACHE_DATA_ID).eval(null);
		
}

Please give some suggestion.

[Andrej_Bogdanov]

Hello,

We have posted a few blog posts regarding custom snap development on our website. I am sending you the URL for the 3 custom snaps developed by us that we have published so far, I believe you will find them useful. If you have any questions you can reach out to us.

Sleep snap: https://interworks.com.mk/development-of-custom-sleep-snap-for-snaplogic-platform/
Flow Reset snap: https://interworks.com.mk/development-of-a-custom-flow-reset-snap-for-the-snaplogic-platform/
Generic JDBC - Table Operation snap: https://interworks.com.mk/generic-jdbc-table-operation-custom-developed-snap/

Regards

[ashlam]

Hi,
Cant able to acces the URL’s above.

Many thanks for taking time and replying for the post.

Regards,
Ashlam

[rohithmadhavan]

You’ll need to evaluate the ExpressionProperty against the input document, not null. This cannot be done in the configure() method, use process() instead:

ExpressionProperty valueCategoryExp;
String valueCategory;

@Override
public void configure(PropertyValues propertyValues) throws ConfigurationException {
	valueCategoryExp = propertyValues.getAsExpression(CACHE_DATA_ID);
}

@Override
protected void process(Document document, String s) {
        valueCategory = valueCategoryExp.eval(document);
}