查询documentdb中的子字段 [英] Querying a subfield in documentdb

问题描述

例如，我下面有一个用于收集=交货的文档:

For example I have a document below for collection = delivery:

{
    "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?

is it possible to do a search with "deliverynum" = 999 and the output would be like below?

{
    "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?

or should I make another Collection just for the Doc part?

在这种情况下，我很难用C#进行查询.

I am having trouble making a query in C# for this kind of scenario.

推荐答案

在Mongo shell中，您可以使用 $(投影)运算符:

In Mongo shell you can use the $(projection) operator:

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

对应的C#代码如下所示:

Corresponding C# code can look like below:

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();

如果您要获取所有文档(即使其中不包含deliverynum =``999

You can also use q = Builders<Model>.Filter.Empty if you want to get all documents even if the don't contain deliverynum =``999

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