如何修复“无法将当前 JSON 数组反序列化为类型 'passages' 因为需要 JSON 对象（例如 {"name":"value"}）来反序列化

Question

我正在尝试使用 c# 中的 newtonsoft.json 从本地目录读取和访问大型 JSON 文件，但总是给我错误。我创建了两个类来访问它。这是我的示例 JSON 数据：

{
    "passages": [
        {
            "passage_text": "xxxxxxx",
            "url": "xxxxx",
        }
    ]
    "answer":"xxxxxx",
    "query_id":"Xxxxx"
}

这是我试过的代码：

public class collection
{
    public passages passages { get; set; }
    public String answers { get; set; }
    public String query_id { get; set; }
}

public class passages
{
    public String url { get; set; }
    public String passage_text { get; set; }
}

这是我试图阅读和访问 JSON 文件的部分：

String jsonPath = @"C:\Users\admin\Desktop7\project\collection\sample_collection.json"  ;
var serializer = new JsonSerializer();
StreamReader sr = new StreamReader(jsonPath);
JsonTextReader reader = new JsonTextReader(sr);
reader.SupportMultipleContent = true;
while (reader.Read())
{
    if (reader.TokenType == JsonToken.StartObject)
    {
        collection c = serializer.Deserialize<collection>(reader);
        Console.WriteLine(c.passages.url);
     }
}

它给了我这个错误：

Newtonsoft.Json.JsonSerializationException: 'Cannot deserialize the current JSON array (e.g. [1,2,3]) into type 'LuceneIndexApplication.passages' because the type requires a JSON object (e.g. {"name":"value"}) to deserialize correctly. To fix this error either change the JSON to a JSON object (e.g. {"name":"value"}) or change the deserialized type to an array or a type that implements a collection interface (e.g. ICollection, IList) like List that can be deserialized from a JSON array. JsonArrayAttribute can also be added to the type to force it to deserialize from a JSON array. Path '[0].passages', line 1, position 15.'

Answer 1

您正在尝试将数组中的段落映射到列表中。

所以您需要更改的是：

public class collection
    {
        public passages passages { get; set; }
        public String answers { get; set; }
        public String query_id { get; set; }
    }

应该是

public class collection
    {
        public List<passages> passages { get; set; }
        public String answers { get; set; }
        public String query_id { get; set; }
    }

注意后面的List

如何修复“无法将当前 JSON 数组反序列化为类型 'passages' 因为需要 JSON 对象（例如 {"name":"value"}）来反序列化

How to fix 'Cannot deserialize the current JSON array into type 'passages' because requires a JSON object (e.g. {"name":"value"}) to deserialize

c#

json

lucene.net