maping of JSON response using jackson

Question

I have a rest endpoint with the following response

{
    "Shops": {
        "Shop": [
            {
                "RowID": "1",
                "Penalties": {
                    "Penalty": [
                        {
                            "PenaltyCode": "abc-01",
                            "PenaltyCount": "1"
                        },
                        {
                            "PenaltyCode": "abc-02",
                            "PenaltyCount": "2"
                        }
                    ]
                },
                "VisitOutComes": {
                    "VisitOutCome": {
                        "TaskOutComeName": "text",
                        "TaskOutComeCount": "1"
                    }
                }
            }
        ]
    }
}

I need to insert the response in a RDMS using hibernate. I already done the hibernate part and the rest client part. I am confused how to map the json to java classes.

I write the follwing classes , getter and setter are omitted for clarity.

public class Shops {
    @JsonProperty("Shop")
    private ArrayList<Shop> shop ;



    public class Shop {
        @JsonProperty("VisitOutComes")
        private VisitOutComes  visitOutComes ;
        
        @JsonProperty("Penalties")
        private Penalties  penalties ;
    
        @JsonProperty("RowID")
        private String rowID ;
    
    public class VisitOutComes {
        @JsonProperty("VisitOutCome")
        ArrayList<VisitOutCome> visitOutCome ;
    
    
    public class Penalties {
        @JsonProperty("Penalty")
        ArrayList<Penalty> penalty ;
    
    
    public class VisitOutCome {
        @JsonProperty("TaskOutComeCount")
        private String TaskOutComeCount;
        
        @JsonProperty("TaskOutComeName")
        private String TaskOutComeName ;
    
    
    public class Penalty {
        @JsonProperty("penaltyCode")
        private String penaltyCode ;
        
        @JsonProperty("penaltyCount")
        private String penaltyCount ;

Then I wirte the main method as follows :

ObjectMapper mapper = new ObjectMapper();
mapper.disable(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES);
mapper.configure(DeserializationFeature.UNWRAP_ROOT_VALUE, true);
String path = "C:\\jars\\response.json" ;
Shops shops = mapper.readValue(new File(path),Shops.class);

Finally I get the error

Cannot deserialize instance of java.util.ArrayList jscksondemo.VisitOutCome out of START_OBJECT token

I appreciate any help on how to create the maping for this json file.

That is because the rest web service returned it this way when there is only one item. — Ahmed Mohamed, Sep 14 '20 at 11:34
I think it would be a better design to you keep your hibernate entity (modelled based on the tables) separate from the API response. And you write converter class to convert between 2 formats. This will safeguard your database layer code and entities from being directly affected by changes in API response, This will also help you to handle your current case where an attribute could be an array or object. — Smile, Sep 14 '20 at 11:53
You need to enable `DeserializationFeature.ACCEPT_SINGLE_VALUE_AS_ARRAY` feature. Take a look on linked question. — Michał Ziober, Sep 14 '20 at 12:06

score 0 · Answer 1 · answered Sep 14 '20 at 11:00

0

Try with this JSON:

{
    "Shops": {
        "Shop": [
            {
                "RowID": "1",
                "Penalties": {
                    "Penalty": [
                        {
                            "PenaltyCode": "abc-01",
                            "PenaltyCount": "1"
                        },
                        {
                            "PenaltyCode": "abc-02",
                            "PenaltyCount": "2"
                        }
                    ]
                },
                "VisitOutComes": {
                    "VisitOutCome": [
                        {
                            "TaskOutComeName": "text",
                            "TaskOutComeCount": "1"
                        }
                    ]
                }
            }
        ]
    }
}

I think the bracket of your VisitOutCome List is not right.

answered Sep 14 '20 at 11:00

danielbene

25
6

Actually I get json from a rest webservies , I can't edit. – Ahmed Mohamed Sep 14 '20 at 11:10
I also verfied it using the link https://jsonlint.com/ – Ahmed Mohamed Sep 14 '20 at 11:10
I got your idea , i my sample json there is only one visitOutcome that is why it is formated this way. But in real situation visitOutcome may be an array and may be single item. – Ahmed Mohamed Sep 14 '20 at 11:14
Yes, I validated it too the syntax is correct. If the json is fixed than the used type in the VisitOutComes class is incorrect. You can see it's the same type as the penalty list, but the retrieved json objects are different structure. – danielbene Sep 14 '20 at 11:16
Yes, list size can cause it too. – danielbene Sep 14 '20 at 11:18

maping of JSON response using jackson

1 Answers1