How to access c8y_PropertyType (custom attributes) in Java SDK?

Question

I'm using the Cumulocity Java SDK and I'm trying to get access of the custom fragment in one of the ManagedObject. Something like that:

...
"type": "sap_CustomomerLocation",
"c8y_PropertyType":{
    "Customer.Name":{ 
        "name":"customerName", 
        "sap_field_name":{
            "requestIdentifier":"SAP",
            "adressIdentifier":"customerName" 
        }
    },
    "Customer.Address":{ 
        "name":"customerAddress", 
        "sap_field_name":{
            "requestIdentifier":"SAP",
            "adressIdentifier":"customerAddress" 
        }
    }
}
...

I can't change the format of the fragment. In Java application I fetch the Mo by:

InventoryFilter filter = new InventoryFilter();
filter.byType("sap_CustomomerLocation");

ManagedObjectCollection configuration = platform.getInventoryApi().getManagedObjectsByFilter(filter);
ManagedObjectRepresentation singleConfig = configuration.get().allPages().iterator().next();

Map<String, Object> attrs = singleConfig.getAttrs();

The problem is that I can't get to the "sap_field_name", attrs is a HashMap@Node. In debugger in IntelliJ, when I use "evaluateExpression" something like that is generated:

((HashMap.Node)((HashMap)((HashMap.Node)((HashMap)((HashMap.Node)((HashMap)((HashMap.Node)((HashMap)attrs).entrySet().toArray()[0]).getValue()).entrySet().toArray()[0]).getValue()).entrySet().toArray()[0]).getValue()).entrySet().toArray()[1]).getValue()

So, can you suggest something? Should I somehow cast it to the DTO? But then how to handle keys in the JSON ("Customer.Name", "Customer.Address") that can change because this is a list of fields.

score 1 · Accepted Answer · answered Jul 02 '18 at 12:53

I tried to create a new class in namespace c8y.PropertyType and it kinda worked, Cumulocity SDK, or rather Jackson JSON founded that there is a class and tried to map it but the problem remains in terms of this dynamic fields.

After small debugging in the Jackson code, I found out that I would need to create a class in right namespace for all custom fields (unfortunately I don't know the names).

So this is a workaround that I found acceptable:

ManagedObjectRepresentation singleConfig;

Map<String, Object> attrs = singleConfig.getAttrs();
ObjectMapper mapper = new ObjectMapper();
JsonNode jsonNode = mapper.valueToTree(attrs);

String customFieldName = jsonNode.get("c8y_PropertyType").get("attrs").iterator().next().get("sap_field_name").get("adressIdentifier").asText();

please tell me what is your main aim which fragments data that you want — Dhanasekaran Don, Jul 03 '18 at 09:10

score 0 · Answer 2 · answered Jun 29 '18 at 15:52

One way you could approach it is to create a model class for your c8y_PropertyType fragment that matches the content. To map this fragment you would need to create a class PropertyType in the package c8y and put it on the class path.

The JSON parser should then no longer generate this HashMap structure but your class. I am not really sure if the dots in the JSON keys lead to problems here.

If you need examples for such classes check https://bitbucket.org/m2m/cumulocity-clients-java/src/03e47693b1d389308901347d224c13d81250b703/device-capability-model/?at=develop

How to access c8y_PropertyType (custom attributes) in Java SDK?

2 Answers2