获取mongodb subDocument

Question

考虑以下数据

{
"_id" : ObjectId("580bc94b221036257caf2636"),
"Status" : "Scheduled",
//I want to get this Questions list
"Questions" : [ 
    {
        "QuestionType" : "Choice",
        "Question" : "What is your name?",
        "Correct" : "C",
        "Options" : [ 
            "xxx", 
            "xxx", 
            "xxx"
        ]
    },
{
        "QuestionType" : "Choice",
        "Question" : "What is your name?",
        "Correct" : "C",
        "Options" : [ 
            "xxx", 
            "xxx", 
            "xxx"
        ]
    }
]

}

这是我的查询

var collection = mongodb.GetCollection<QuestionsList>("Papers");
        var choice = collection.Find(Query.EQ("userName", "Sohail")).SetFields(Fields.Exclude("status")
            .Slice("Questions", 1)).Single();
        return choice.multiQuestions.ToList();

在过去的一周里，我一直在尝试这个问题，但是似乎没有什么可以解决的，我的问题是如何获得这个问题列表并将其显示给我的MVC视图？？谢谢

Answer 1

首先，您似乎在查询文档上的用户名字段，而您似乎没有基于上面提供的数据结构：

.Find(Query.EQ("userName", "Sohail"))

但假设这是个错误..。

您可以在这里使用$project返回嵌入的问题数组：

var collection = mongodb.GetCollection<QuestionsList>("Papers");

var projection = Builders<QuestionsList>.Projection.Include("Questions");
var choice = collection
                 .Find(Query.EQ("userName", "Sohail"))
                 .Project(projection)
                 .ToList();

return choice;

看起来您有一个C#模型(QuestionsList)，所以您没有使用强类型查询吗？假设您的模型如下所示：

public class QuestionsList
{
    [BsonRepresentation(BsonType.ObjectId)]
    [BsonId]
    public string Id { get; set; }

    //Missing from your data structure but assume it is there
    public string userName { get; set; }

    public string Status { get; set; }

    public List<Question> Questions { get; set; }
}

public class Question
{
    public string QuestionType { get; set; }
    public string Question { get; set; }
    public string Correct { get; set; }
    public List<string> Options { get; set; }
}

等价物

var choice = collection
                 .Find(x => x.userName == "Sohail"))
                 .Project(x => x.Questions)
                 .ToList();