以下是收集内容的示例：

• 博客作者 *

[
    {
        _id: ObjectId(...),
        posts: [
            {
                "platform": "instagram"
            },
            {
                "platform": "tiktok"
            },
        ],
        full_name: "John Doe",
    },
    {
        _id: ObjectId(...),
        posts: [
            {
                "platform": "youtube"
            },
            {
                "platform": "tiktok"
            },
        ],
        full_name: "Mamed Mamedov"
    }
]

作为聚合的结果，我想得到这样的结果：

[
    {
        _id: ObjectId(...),
        platforms: ["instagram", "tiktok"],
        full_name: "John Doe",
    },
    {
        _id: ObjectId(...),
        platforms: ["youtube", "tiktok],
        full_name: "Mamed Mamedov"
    }
]

(List posts字段中的平台数量）
到目前为止，我甚至不确定mongodb中是否有现成的方法。