我正在尝试通过MongoDB Java Driver更新子文档。
我在Mongo中有以下结构:
{
"_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"
}
}
使用Java驱动程序,我可以通过这种方式更新根文档“numberOfDownloads”字段:
Document updDocQuery = new Document("_id", "9999996978c9df5b02999999");
Document updDocValues = new Document("numberOfDownloads","555");
Document updDocSet = new Document("$set",updDocValues);
System.out.println(updDocSet.toJson());
collection.updateOne(updDocQuery, updDocSet);
哪种方法正常。
现在我也在尝试更新SubDocument“文档”以将“下载”值设置为相同 - 我正在尝试这样的事情:
Document updDocQuery = new Document("_id", "9999996978c9df5b02999999");
Document updDocValues = new Document("numberOfDownloads","555");
Document updSubDocValues = new Document("downloads","555");
updDocValues.append("documents", updSubDocValues);
Document updDocSet = new Document("$set",updDocValues);
System.out.println(updDocSet.toJson());
collection.updateOne(updDocQuery, updDocSet);
正在将“documents”属性正式更新为我的新值 - 但我想更新特定字段并保持其他字段不变。
我最终在Mongo中得到了一份结果文件:
{
"_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:
{
"_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"
}
}
我宁愿不必拉记录,将其转换为对象,更新值并提交更新 - 但这似乎效率低下。
我可以从Mongo控制台执行此查询,效果很好:
db.Paper.update(
{"_id" : "5617776978c9df5b02f68228"},
{$set:
{ "numberOfDownloads" : "453",
"documents" :
{ "downloads" : "453"}
}
});
我只是错过了一些简单的东西 - 或者我是非常过于复杂吗?
答案 0 :(得分:2)
如果这是mongodb中设置的更新:
{$set:
{ "numberOfDownloads" : "453",
"documents" :
{ "downloads" : "453"}
}
}
您可以这样使用Document类:
Document upDocValue = new Document("numberOfDownloads": "453")
.append("documents.downloads":"453");
这会给你:
{
"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("$set",updDocValue);
这应该给你:
{$set:
{ "numberOfDownloads" : "453",
"documents" :
{ "downloads" : "453"}
}
}
然后在这里运行您的查询:
collection.updateOne(upDocQuery,upDocSet);
所以你最终拥有:
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);