如何在java中用'equality'查询mongodb

Question

我在Mongodb中关注了BSON

{
    "_id" : ObjectId("52a30bdfaaa83ba83c25c0f3"),
    "course" : {
        "course_name" : "Java EE",
        "description" : "Java Enterprise Edition"
    },
    "first_name" : "Lucy",
    "last_name" : "Hill",
    "gender" : "female"
}

我想找到所有包含“course_name”=“Java EE”的文档。在java中，我尝试过这段代码，但它似乎没有用。

DBCollection table = db.getCollection("Students"); //my Collection
BasicDBObject courseNameDBObject = new BasicDBObject() 
            .append("course", new BasicDBObject("course_name", "Java EE"));
DBCursor cursor = table.find(courseNameDBObject);
while(cursor.hasNext()){
    System.out.println(cursor.next());
}

有人可以帮助我吗？

Answer 1

DBCollection table = db.getCollection("Students"); //my Collection
BasicDBObject courseNameDBObject = new BasicDBObject("course.course_name", "Java EE") ;
DBCursor cursor = table.find(courseNameDBObject);
while(cursor.hasNext()){
    System.out.println(cursor.next());
}

您可以使用.访问子文档中的字段。

Official documentation on querying