LINQ on polymorphic json 获取逗号分隔字段

Question

我有一个多态 json 字符串。这是它的样子：

{
    "?xml" : {
        "@version" : "1.0",
        "@encoding" : "UTF-8"
    },
    "DataFeed" : {
        "@FeedName" : "complianceCompany",
        "Companies" : {
            "@timeStamp" : "2016-07-06T10:16:51.00",
            "Company" : [{
                    "@id" : "1",
                    "Ticker" : "MSFT-NSDQ",
                    "Name" : "Microsoft",
                    "Disclosure" : {
                        "@Code" : "25",
                        "@Description" : "25: PERSON FINANCIAL INTEREST"
                    }
                }, {
                    "@id" : "3",
                    "Ticker" : "AAPL-NSDQ",
                    "Name" : "Apple",
                    "Disclosure" : [{
                            "@Code" : "3",
                            "@Description" : "03: RECEIVED COMP FOR NON-IB SVS"
                        }, {
                            "@Code" : "6C",
                            "@Description" : "06C: CLIENT NON SEC REL SVS"
                        }, {
                            "@Code" : "39",
                            "@Description" : "39: MARKET MAKER"
                        }
                    ]
                }
            ]
        }
    }
}

曾经有人帮我做了以下扩展 class:

public static class JsonExtensions
{
    public static IEnumerable<JObject> ObjectsOrSelf(this JToken root)
    {
        if (root is JObject)
            yield return (JObject)root;
        else if (root is JContainer)
            foreach (var item in ((JContainer)root).Children())
                foreach (var child in item.ObjectsOrSelf())
                    yield return child;
        else
            yield break;
    }
}

基于此，这是我的查询：

JObject feed = JObject.Parse(jsonText);

var discInfo = from issuer in feed.SelectTokens("DataFeed.Companies.Company").SelectMany(i => i.ObjectsOrSelf())
   let discs = issuer.SelectTokens("Disclosure").SelectMany(s => s.ObjectsOrSelf())
   select new
    {
        Id = (int)issuer["@id"],
        Ticker = (string)issuer["Ticker"],
        CompName = (string)issuer["Name"],
        DiscCode = (string)discs["@Code"],
    };

当我尝试查询时，出现以下错误：

Cannot apply indexing with [] to an expression of type 'IEnumerable<JObject>'

我正在尝试在逗号分隔的字段中为每个代码获取所有光盘。最终结果应如下所示：

如何获得最终结果？

Answer 1

当你做...

DiscCode = (string)discs["@Code"]

...您正在尝试访问披露 JObject 的属性 "@Code"。但是 discs 是 IEnumerable<JObject> 类型的！您必须收集 discs 中的所有 "@Code" 并将它们连接起来。

LINQ 的 Aggregate() can do this, but I think it always looks more readable to use string.Join() 为此：

DiscCode = string.Join(", ", discs.Select(d => (string)d["@Code"]))

LINQ on polymorphic json 获取逗号分隔字段

LINQ on polymorphic json to get a comma separated field

c#

json.net

c#-4.0

linq-to-json