Write custom document to Cosmos DB with Java API

I have a Cosmos DB and want to write different kind of documents to it. The structure of the documents is dynamic and can change.

I tried the following. Let's say I have the following class:

class CosmosDbItem implements Serializable {
    private final String _id;
    private final String _payload;

    public CosmosDbItem(String id, String payload) {
      _id = id;
      _payload = payload;
    }

    public String getId() {
      return _id;
    }

    public String getPayload() {
      return _payload;
    }
  }

I can create then the document with some JSON as follows:

CosmosContainer _container = ...
CosmosDbItem dataToWrite = new CosmosDbItem("what-ever-id-18357", "{\"name\":\"Jane Doe\", \"age\":42}")
item = _cosmosContainer.createItem(dataToWrite, partitionKey, cosmosItemRequestOptions);

This results in a document like that:

{
    "id": "what-ever-id-18357",
    "payload": "{\"name\":\"Jane Doe\", \"age\":42}",
    "_rid": "aaaaaaDaaAAAAAAAAAA==",
    "_self": "dbs/aaaaAA==/colls/aaaaAaaaDI=/docs/aaaaapaaaaaAAAAAAAAAA==/",
    "_etag": "\"6e00c443-0000-0700-0000-5f8499a70000\"",
    "_attachments": "attachments/",
    "_ts": 1602525607
}

Is there a way in generating the payload as real JSON object in that document? What do I need to change in my CosmosDbItem class? Like this:

{
    "id": "what-ever-id-18357",
    "payload": {
                 "name":"Jane Doe",
                 "age":42
               },
    "_rid": "aaaaaaDaaAAAAAAAAAA==",
    "_self": "dbs/aaaaAA==/colls/aaaaAaaaDI=/docs/aaaaapaaaaaAAAAAAAAAA==/",
    "_etag": "\"6e00c443-0000-0700-0000-5f8499a70000\"",
    "_attachments": "attachments/",
    "_ts": 1602525607
}

Here is my solution that I ended up. Actually it is pretty simple once I got behind it. Instead of using CosmosDbItem I use a simple HashMap<String, Object>.

public void writeData() {
    ...
    Map<String, Object> stringObjectMap = buildDocumentMap("the-id-", "{\"key\":\"vale\"}");
    _cosmosContainer.createItem(stringObjectMap, partitionKey, cosmosItemRequestOptions);
    ...
  }
  
  public Map<String, Object> buildDocumentMap(String id, String jsonToUse) {
    JSONObject jsonObject = new JSONObject(jsonToUse);
    jsonObject.put("id", id);
    return jsonObject.toMap();
  }

This can produce the following document:

{
    "key": "value",
    "id": "the-id-",
    "_rid": "eaaaaaaaaaaaAAAAAAAAAA==",
    "_self": "dbs/eaaaAA==/colls/eaaaaaaaaaM=/docs/eaaaaaaaaaaaaaAAAAAAAA==/",
    "_etag": "\"3b0063ea-0000-0700-0000-5f804b3d0000\"",
    "_attachments": "attachments/",
    "_ts": 1602243389
}

One remark: it is important to set the id key in the HashMap. Otherwise one will get the error

"The input content is invalid because the required properties - 'id; ' - are missing"