Fetch and Update Nested JSON attribute value

Question

I have a nested JSON which looks like this.

{
"eventId" : "12345",
"eventName" : "carnival",
"object": {
    "objectId" : "5678",
    "objectFiles" : [{"fileName":"text.txt", "fileContent":"This is a test file."},
                    {"fileName":"text2.txt", "fileContent":"This is a test2 file."}]
    }
}

Here I have to fetch the eventFiles key, replace the fileContent value with Base64Encoded String and place it back to the same eventFiles attribute. I know that I can use Jackson Mapper to convert it into Map and iterate them one by one, untill I find eventFiles key, then fetch and replace the value and store it back again. I tried to convert it as a Map using TypeReference<String, Object> or even TypeReference<Map<String, Map<String, Object>>> but the problem here is the nested JSON where ultimately it would become Map inside of a Map inside of a Map which would become pretty complex to handle.

Is there any other simpler way to accomplish this? Any suggestions would be really helpful. Thanks in advance.

Denis · Accepted Answer · 2017-07-04 21:15:24Z

2

If your Json has a fixed format you can use Gson (https://github.com/google/gson) and convert it to an Object that represent your json.

It would look something like this:

public class CustomEvent {
    String eventId;
    String eventName;
    CustomObject object;
}

public class CustomObject {
    String objectId;
    List<CustomFile> objectFiles;
}

public class CustomFile {
    String fileName;
    String fileContent;
}

And you could use it like this:

Gson gson = new Gson();
CustomEvent event = gson.fromJson(yourString, Event.class)
// Do whatever you want with the event

String modifiedJson = gson.toJson(event);

Hope it helped

answered Jul 4, 2017 at 21:15

Denis

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1 Comment

15R6 Over a year ago

thanks for your answer. I would not have a fixed format. It keeps changing. So dynamically I have to accomplish this.

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