Gson to json dynamically add map to object
I have an object that represents an event that I would like to serialize to json using gson or another library if that would work easier.
I want to add the following field type to json:
private Map<String, String> additionalProperties;
And also in another case:
private Map<String, Object> additionalProperties;
But if I add additional properties to the Event object and create the Gson in the usual way:
Gson gson = BUILDER.create();
String json = gson.toJson(event);
It will look like this:
additional_properties: {"value1":1,"value2":"abc"}
I would just like to add the following form to the event object:
{"value1":1,"value2":"abc"}
Here's an example of the output - the additional properties added are the 'z' object and the advertiser of the object:
{"organisationid":"2345612ß","projectid":"12345678",
"place":{"placeId":"2345","last_place":"123-3"},
"advertiser":{"advertiserId":"2345a","code":"a123-3"},
"user":{"isY":false,"isHere":false,"isBuyer":false},
"x":{"identifier":"SHDG-28CHD"},
"z":{"identifier":"abcSHDG-28CHD"},
"event_type":"x_depart"}
This is what it looks like now:
{"organisationid":"2345612ß","projectid":"12345678",
"place":{"placeId":"2345","last_place":"123-3"},
additionalproperty: {"advertiser":{"advertiserId":"2345a","code":"a123-3"},
"user":{"isY":false,"isHere":false,"isBuyer":false},
"x":{"identifier":"SHDG-28CHD"},
additionalproperty: {"z":{"identifier":"abcSHDG-28CHD"}},
"event_type":"x_depart"}
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The best way to solve this is to create a framework to add properties dynamically, but without that you can add additional properties to the Event object (including @JsonIgnore so it is not part of the final json), create a new JSONObject from the additional properties, and combine it into a JSONObject event before serialization to json. Thus, additional properties are added dynamically to the resulting Event output.
In the Event class:
@JsonIgnore
private Map<String, Object> additionalProperties;
public Map<String, Object> getAdditionalProperties() {
return this.additionalProperties;
}
public void setAdditionalProperties(Map<String, Object> additionalProperties) {
this.additionalProperties = additionalProperties;
}
Function to combine two JSONObjects:
public static JSONObject mergeObjects(JSONObject source, JSONObject target) throws JSONException {
for (String key: JSONObject.getNames(source)) {
Object value = source.get(key);
if (!target.has(key)) {
// new value for "key":
target.put(key, value);
} else {
// existing value for "key" - recursively deep merge:
if (value instanceof JSONObject) {
JSONObject valueJson = (JSONObject)value;
deepMerge(valueJson, target.getJSONObject(key));
} else {
target.put(key, value);
}
}
}
return target;
}
Combining two objects:
String jsonAdd = mapper.writeValueAsString(additional);
String jsonEvent = mapper.writeValueAsString(event);
JSONObject jsonAddObj = new JSONObject(jsonAdd);
JSONObject JsonEventObj = new JSONObject(jsonEvent);
JSONObject finalJson = Merge.deepMerge(jsonAddObj, JsonEventObj);
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If your class Event
is something like:
class Event {
private Map<String, Object> additionalProperties;
}
and you call;
String json = gson.toJson(event);
Expected and Actual Output:
{"additionalProperties":{"value1":1,"value2":"abc"}}
If you want an output like:
{"value1":1,"value2":"abc"}
You may call:
String json = gson.toJson(event.additionalProperties);
I just would like to add the following form to the event object:
{"value1":1,"value2":"abc"}
So it won't be a valid json variable if you add that value directly to the json object. You better try if the json value you want is valid or not, http://jsonviewer.stack.hu/
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