如何在Elastic Search中增加具有动态属性的嵌套对象？

我在elasticsearch中有一个看起来像这样的文档：

{
    "_index": "stats",
    "_type": "_doc",
    "_id": "1",
    "_score": 1.0,
    "_source": {
        "publishTime": {
            "lastUpdate": 1580991095131,
            "h0_4": 0,
            "h4_8": 0,
            "h8_12": 3,
            "h12_16": 5,
            "h16_20": 2,
            "h20_24": 1
        },
        "postCategories": {
             "lastUpdate": 1580991095131,
             "tech": 56,
             "lifestyle": 63,
             "healthcare": 49,
             "finances": 25,
         }
     }
 }

通过发送POST请求来更新/增加现有属性值，/stats/_update/1效果很好！但是，如果尝试在下添加一个不存在的属性名称，则会postCategories收到Bad Request (400)类型为error的错误remote_transport_exception/illegal_argument_exception：

"ctx._source.postCategories.relationships += params.postCategories.relationships",
                                                                  ^---- HERE"

哎呀

{
    "script": {
        "source": "ctx._source.postCategories.relationships += params.postCategories.relationships",
        "lang": "painless",
        "params": {
            "postCategories": {
                "relationships": 2
            }
        }
    },
    "upsert": {
       "postCategories": {
            "relationships": 2
        }
    }
}

我还按照此处的文档尝试了Scripted Upsert方法，但是，发生了相同的错误：

脚本更新

{
    "scripted_upsert":true,
    "script": {
        "source": "ctx._source.postCategories.relationships += params.postCategories.relationships",
        "params": {
            "postCategories": {
                "relationships": 2
            }
        }
    },
    "upsert": {}
}

谁能告诉我如何在postCategories对象下正确添加/添加新的属性名称？

谢谢！