Using Jackson to deserialize JSON to Map

Question

I am trying to find an easy way to deserialize the following JSON to an OpeningHours Object containing a Map<String, List<String>> which contains the days as keys and the opening hours as a list.

I am using Jackson and created my own deserializer @JsonDeserialize(using = MyDeserializer.class) The problem is that I need to check which of the different JSON nodes is present to set the keys for the map.

Is there an easy alternative solution?

{
  "OpeningHours": {
    "Days": {
      "Monday": {
        "string": [
          "09:00-13:00",
          "13:30-18:00"
        ]
      },
      "Tuesday": {
        "string": [
          "09:00-13:00",
          "13:30-18:00"
        ]
      }
    }
  }
}

Answer 1

You could just deserialize it to a data structure that represents the JSON like

@Data
public class TempStore {

    private List<DayTempStore> days;
}

@Data 
public class DaytempStore {

    private String[] string;
}

and just transform this to a Map> leaving the hassle with Nodes and Checks to Jackson.

Answer 2

Jackson can deserialize any Json into Map<String, Object> , that may contain nested maps for nested json objects. all that is needed is casting:

String json = ...
ObjectMapper mapper = new ObjectMapper();
Map<String, Object> openingHours = (Map<String, Object>)mapper.readValue(json, Map.class);
Map<String, List<String>> days = (Map<String, List<String>>)((Map<String, Object>)openingHours.get("OpeningHours")).get("Days");
System.out.println(days);

output:

 {Monday={string=[09:00-13:00, 13:30-18:00]}, Tuesday={string=[09:00-13:00, 13:30-18:00]}}

Answer 3

I think you are making the issue is a bit more complex than it is. You don't need a custom deserializer in this case. All you need is this:

ObjectMapper objectMapper = new ObjectMapper();
objectMapper.registerModules(new JavaTimeModule());
ObjectReader obrecjReader = objectMapper.reader();
Map<String, Object> myMap = objectReader.forType(Map<String,Object>.class).readValue(jsonString);