MongoDB Java驱动程序更新子文档

Question

我正在尝试通过MongoDB Java驱动程序更新子文档。

我在Mongo中具有以下结构：

    {
        "_id" : "9999996978c9df5b02999999",
        "title" : "The Effects of Glaze on Pottery",
        "numberOfDownloads" : "453",
        "summary" : "This is a summary of the document",
        "documents" : {
                "file" : "99991F64C16E9A0954E89999",
                "mimetype" : "document/pdf",
                "pages" : "415",
                "downloads" : "453"
        }
}

并使用Java驱动程序，可以通过以下方式很好地更新根文档“ numberOfDownloads”字段：

        Document updDocQuery = new Document("_id", "9999996978c9df5b02999999");

        Document updDocValues = new Document("numberOfDownloads","555");

        Document updDocSet = new Document("$set",updDocValues);

        System.out.println(updDocSet.toJson());

        collection.updateOne(updDocQuery, updDocSet);

哪个工作正常。

现在，我还尝试更新SubDocument的“文档”，以将“下载”值设置为相同的值-我正在尝试如下操作：

        Document updDocQuery = new Document("_id", "9999996978c9df5b02999999");

        Document updDocValues = new Document("numberOfDownloads","555");

        Document updSubDocValues = new Document("downloads","555");

        updDocValues.append("documents", updSubDocValues);
        Document updDocSet = new Document("$set",updDocValues);

        System.out.println(updDocSet.toJson());

        collection.updateOne(updDocQuery, updDocSet);

它将适当地将“ documents”属性更新为我的新值-但我想更新特定字段并保留其他字段不变。

我最终在Mongo中生成了以下文档：

    {
        "_id" : "9999996978c9df5b02999999",
        "title" : "The Effects of Glaze on Pottery",
        "numberOfDownloads" : "555",
        "summary" : "This is a summary of the document",
        "documents" : {
                "downloads" : "555"
        }
}

我需要它是：

    {
        "_id" : "9999996978c9df5b02999999",
        "title" : "The Effects of Glaze on Pottery",
        "numberOfDownloads" : "555",
        "summary" : "This is a summary of the document",
        "documents" : {
                "file" : "99991F64C16E9A0954E89999",
                "mimetype" : "document/pdf",
                "pages" : "415",
                "downloads" : "555"
        }
}

我希望不必拉记录，将其转换为对象，更新值并提交以进行更新-但这似乎效率很低。

我可以从Mongo Console执行此查询，并且效果很好：

db.Paper.update(
    {"_id" : "5617776978c9df5b02f68228"},
    {$set: 
        { "numberOfDownloads" : "453", 
          "documents" : 
                { "downloads" : "453"}
        }
    });

我只是错过了一些简单的东西吗-或-我是否过于复杂化了？

Answer 1

如果这是在mongodb中设置的更新：

 {$set: 
        { "numberOfDownloads" : "453", 
          "documents" : 
                { "downloads" : "453"}
        }
 }

您可以通过以下方式使用Document类：

Document upDocValue = new Document("numberOfDownloads": "453")
                      .append("documents.downloads":"453");

这将为您提供：

{
  "numberOfDownloads": "453",
  "documents" : 
    { "downloads" : "453"}
}

然后，您可以使用以下命令创建外部文档：

Document upDocSet = new Document("$set",updDocValue);

这应该给您：

{$set: 
      { "numberOfDownloads" : "453", 
            "documents" : 
                  { "downloads" : "453"}
      }
}

然后，您在此处运行查询：

collection.updateOne(upDocQuery,upDocSet);

因此，您最终拥有：

Document updDocQuery = new Document("_id", "9999996978c9df5b02999999");

Document upDocValue = new Document("numberOfDownloads": "453")
                          .append("documents.downloads":"453");

Document upDocSet = new Document("$set",updDocValue);

collection.updateOne(upDocQuery,upDocSet);