Question

例如，我下面有一个用于收集=交货的文档：

{
    "doc": [
        {
            "docid": "15",
            "deliverynum": "123",
            "text": "txxxxxx",
            "date": "2019-07-18T12:37:58Z"
        },
        {
            "docid": "16",
            "deliverynum": "456",
            "text": "txxxxxx",
            "date": "2019-07-18T12:37:58Z"
        },
        {
            "docid": "17",
            "deliverynum": "999",
            "text": "txxxxxx",
            "date": "2019-07-18T12:37:58Z"
        }
    ],
    "id": "123",
    "cancelled": false
}

是否可以使用“ deliverynum” = 999进行搜索，并且输出如下所示？

{
    "doc": [        
        {
            "docid": "17",
            "deliverynum": "999",
            "text": "txxxxxx",
            "date": "2019-07-18T12:37:58Z"
        }
    ],
    "id": "123",
    "cancelled": false
}

还是我应该为文档部分创建另一个收藏集？

在这种情况下，我很难用C＃进行查询。

Answer 1

在Mongo shell中，您可以使用$(projection)运算符：

db.collection.find({ "doc.deliverynum": "999" }, { "doc.$": 1 })

对应的C＃代码如下所示：

var q = Builders<Model>.Filter.ElemMatch(x => x.doc, d => d.deliverynum == "999");
var p = Builders<Model>.Projection.ElemMatch(x => x.doc, d => d.deliverynum == "999");

var data = Col.Find(q).Project(p).ToList();

即使您要获取所有文档，即使其中不包含q = Builders<Model>.Filter.Empty，也可以使用deliverynum =``999

查询documentdb中的子字段

1 个答案: