Deserialize values in a tree structured JSON using Jackson

Question

Need to deserialize a JSON structure like below using Jackson, this is a response from a REST API and I am using Spring RestTemplate with MappingJackson2HttpMessageConverter to parse it.

Problems: 1. All elements can have one or more child elements of its own type (e.g. root has children : childABC & childAnyRandomName) 2. Child nodes do not have a standard naming convention, names can be any random string.

{ "FooBar": { "root": { "name": "test1", "value": "900", "childABC": { "name": "test2", "value": "700", "childXYZ": { "name": "test3", "value": "600" } }, "childAnyRandomName": { "name": "test4", "value": "300" } } } }

As per my understanding, a POJO to store this could be something like this:

import java.util.Map;

public class TestObject {

private String name;
private String value;
private Map<String, TestObject> children;

public String getName() {
    return name;
}

public void setName(String name) {
    this.name = name;
}

public String getValue() {
    return value;
}

public void setValue(String value) {
    this.value = value;
}

public Map<String, TestObject> getChildren() {
    return children;
}

public void setChildren(Map<String, TestObject> children) {
    this.children = children;
}

}

I have no control over the actual JSON that I am parsing so If Jackson does not work, I will have to push all of it in JsonNode and build this object structure with custom logic.

Disclaimer: I am relatively new to Jackson, so please don't mind if this was a classic text book solution that I didn't read, just point me to the documentation location.

Answer 1

In your bean, have the attributes you know are there:

private String blah;

@JsonProperty("blah")
@JsonSerialize(include = Inclusion.NON_NULL)
public String getBlah() {
    return blah;
}

@JsonProperty("blah")
public void setBlah(String blah) {
    this.blah = blah;
}

Then, add the following, which is kinda like a catch-all for any properties which you haven't explicitly mapped that appear on the JSON:

private final Map<String, JsonNode> properties = new HashMap<String, JsonNode>();

@JsonAnyGetter
public Map<String, JsonNode> getProperties() {
    return properties;
}

@JsonAnySetter
public void setProperty(String key, JsonNode value) {
    properties.put(key, value);
}

Alternatively, just map known complex objects to Map fields (IIRC, complex objects under that will also end up in maps).