How to create class for dynamic JSON structure in Spring Boot Java

Question

I have following JSON structure as input which can be nested and without nested. I want to fetch the JSON as input and process in Spring Boot application. How to create a class which dynamic key values in the JSON. It can be any key-value pairs in the JSON input. Below is the sample one.

Without Nested:

{
    "mappings": {
        "properties": {
            "firstname": {
                "type": "string"
            },
            "lastname": {
                "type": "string"
            },
            "salary": {
                "type": "integer"
            },
            "date_of_birth": {
                "type": "date"
            }
        }
    }
}

With Nested:

{
    "mappings": {
        "properties": {
            "firstname": {
                "type": "string"
            },
            "lastname": {
                "type": "string"
            },
            "annual_salary": {
                "type": "integer"
            },
            "date_of_birth": {
                "type": "date"
            },
            "comments": {
                "type": "nested",
                "properties": {
                    "name": {
                        "type": "string"
                    },
                    "comment": {
                        "type": "string"
                    },
                    "age": {
                        "type": "short"
                    },
                    "stars": {
                        "type": "short"
                    },
                    "date": {
                        "type": "date"
                    }
                }
            }
        }
    }
}

I don't know how to create a class to support both with and without nested in single class. I have tried the following. It doesn't help.

public class Schema {
    Mapping mappings;

    public Mapping getMappings() {
        return mappings;
    }

    public void setMappings(Mapping mappings) {
        this.mappings = mappings;
    }

    public static class Mapping {
        Property properties;

        public Property getProperties() {
            return properties;
        }

        public void setProperties(Property properties) {
            this.properties = properties;
        }
    }

    public static class Property {
        Map<String, Map<String, Object>> field = new HashMap<>();

        public Map<String, Map<String, Object>> getField() {
            return field;
        }

        public void setField(Map<String, Map<String, Object>> field) {
            this.field = field;
        }
    }
}

Answer 1

I have come across a scenario similar to this where it was possible that my JSON may not be having consistent Key-Value pairs. I gave the following jackson annotation at class level so that whichever property not available in my model and which are present in the JSON will be ignored.

@JsonIgnoreProperties(ignoreUnknown = true)