Java中的MongoDB查询，在嵌套对象中搜索/查找

Z时代
2024-01-10
分类：问答

我在MongoDB上的Java查询中遇到了一些麻烦。

我在数据库中具有以下结构：

{ "_id" : ObjectId("5059c214707747cbc5819f6f"), "id" : "7", "title" : "test4", "keywords" : "keyword 1, keyword 2", "partner" : { "id" : "1", "name" : "partner", "keywords" : "partner keyword 1, partner keyword 2" }, "status" : { "id" : "0", "name" : "Expired" }, "modified" : "2012-09-27" }

我想在数据库中查询字段’Status.name’，例如SELECT * FROM table WHERE status.name =’Expired’

我将如何在Java中为MongoDB进行这样的查询？

感谢您的帮助或建议！

回答：

这是一个例子：

import com.mongodb.Mongo;
import com.mongodb.DBCollection;
import com.mongodb.BasicDBObject;
import com.mongodb.DBCursor;
import com.mongodb.DB;
public class MongoTest {
    public static void main(String[] args) throws Exception {
        // connect to the local database server
        Mongo m = new Mongo();
        DB db = m.getDB( "test" );
        DBCollection coll = db.getCollection("test");
        // delete all the data from the 'test' collection
        coll.drop();
        // make a document
        BasicDBObject doc = new BasicDBObject();
        doc.put("id", 7);
        doc.put("title", "test4");
        doc.put("modified", "2012-09-27");
        BasicDBObject status = new BasicDBObject();
        status.put("id", "1");
        status.put("name", "Expired");
        doc.put("status", status);
        // insert
        coll.insert(doc);
        BasicDBObject query = new BasicDBObject("status.name", "Expired");
        //  run the query and print the results out
        DBCursor cursor = coll.find(query);
        try {
            while (cursor.hasNext()) {
                System.out.println(cursor.next());
            }
        } finally {
            cursor.close();
        }
        m.close();
    }
}