Question

我需要先通过 _id 找到该文档。然后在文档中查找具有Time字段的子文档大于参数 lastTime

var filter = builder.Eq("_id", symbol) & builder.Gt("Update.Time", lastTime);
var result = await MongoDb.CollectionName.Find(filter).ToListAsync();

此示例的结果为0.

如何编写此查询？我需要得到这个子文档＆＃34;更新＆＃34;或最后3个子子文件

该文件具有以下结构

{
  {"_id", symbol},
  {"Update", [
              {"_id", number}, {"Time", sometime}, {"Version", versionNumber}, 
              {"_id", number}, {"Time", sometime}, {"Version", versionNumber},
              {"_id", number}, {"Time", sometime}, {"Version", versionNumber},
              {"_id", number}, {"Time", sometime}, {"Version", versionNumber},}
             ]
}

Answer 1

如果mongodb控制台会起作用的话：

> db.doc.save({
   "_id":"123", 
   "update":[
       {"_id":'1', "time":'345', "Version":'3'}, 
       {"_id":'2', "time":'234', "Version":'4'}
    ]
})
> db.doc.findOne( { _id:"123", "update.time":{ $gt: 344 } } )

那么对于C＃你可以试试吗？

var collection = _database.GetCollection<BsonDocument>("name");
var filter = Builders<BsonDocument>.Filter.Gt("update.time", 344);
var result = await collection.Find(filter).ToListAsync();

这example

UPD这可以是：

var collection = _database.GetCollection<BsonDocument>("name");
var builder = Builders<BsonDocument>.Filter;
var filter  = builder.Eq("_id", id) & builder.Gt("update.time", 344);
var result  = await collection.Find(filter).ToListAsync();

Answer 2

尝试使用lambda表达式：

var lastTime = 1;
var result = collection.Find(x => x.Update.Contains(lastTime));

在子文档MongoDb中查找

2 个答案: