如何Morphia忽略额外的字段/元素？

Question

我是新手，当我使用morphia java mongodb时，我有一个问题。我有“新闻”数据库在mongodb中的收藏是“文章”的一个例子：

{
   "_id": ObjectId("54b77156d52fbb115abbc7ed"),
   "title": "test title",
   "thumbnail": "http://test.com/images/2015/01/15/kt169333-1.jpg",
   "imgsLoc": "/home/test/public/images/2015/01/15/kt169333-1.jpg",
   "sapo": "SampleSapo",
   "author": null,
   "content": "Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam,
quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo
consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse
cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non
proident, sunt in culpa qui officia deserunt mollit anim id est laborum.",
   "source": "http://example.com/news/test/1",
 ... [it has more about 30 fields after this line ...]
}

{
   "_id": ObjectId("54b77156d52fbb115abbc7ed"),
   "title": "test title",
   "thumbnail": "http://test.com/images/2015/01/15/kt169333-1.jpg",
   "imgsLoc": "/home/test/public/images/2015/01/15/kt169333-1.jpg",
   "sapo": "SampleSapo",
   "author": null,
   "content": "Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam,
quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo
consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse
cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non
proident, sunt in culpa qui officia deserunt mollit anim id est laborum.",
"textLength": NumberLong(441) <= new field
   "source": "http://example.com/news/test/1",
 ... [it has more about 30 fields after this line ...]
}

public class Article {
@Id
protected ObjectId id;
protected String content;
protected long textLength;

// Getset method

在不丢失数据的情况下更新集合的最快方法是什么？如何在将这个文章类映射到MongoDB时忽略额外的字段？

谢谢

Answer 1

尽管您没有在代码中显示它，但我假设您在文档上使用了保存。因此，您将它替换为您所拥有的属性，因此出现了“Missing”字段。

如果不想映射整个文档，则需要显式更新字段，而不是简单地调用Save。请参阅关于更新的Morphia文档。