将JSON搜索结果反序列化为强类型列表(JSON.NET)

Question

我在JSON中有搜索结果，我想将其反序列化为强类型对象

例如：

{
    searchresult: {
        resultscount: 15,
        results: [
            {
                resultnumber: 1,
                values: [
                    {
                        key:    "bookid",
                        value:  1424
                    },
                    {
                        key:    "name",
                        value:  "C# in depth"
                    },
                ]
            }
        ]
    }
}

我有这个POCO

public class Book {
    public int BookId { get; set; }
    public string Name { get; set; }
}

我想要一份书单。是的，我可以为这种情况编写自己的自定义反序列化程序，但我想使用默认的反序列化程序。

有可能做那样的事吗？

IEnumerable<Book> books = JsonConvert.DeserializeObject<IEnumerable<Book>>(json);

Answer 1

Json.NET在没有任何自定义的情况下不会执行此操作。您有以下方法：

1. 将您的课程发布到http://json2csharp.com/要创建JSON的文字表示，请使用Linq将结果转换为Book类的列表：

   public class Value
   {
       public string key { get; set; }
       public string value { get; set; } // Type changed from "object" to "string".
   }
   public class Result
   {
       public int resultnumber { get; set; }
       public List<Value> values { get; set; }
   }
   public class Searchresult
   {
       public int resultscount { get; set; }
       public List<Result> results { get; set; }
   }
   public class RootObject
   {
       public Searchresult searchresult { get; set; }
   }
   

   然后

       var root = JsonConvert.DeserializeObject<RootObject>(json);
       var books = root.searchresult.results.Select(result => new Book { Name = result.values.Find(v => v.key == "name").value, BookId = result.values.Find(v => v.key == "bookid").value });
   

2. 创建一个自定义JsonConverter，在读取JSON时将其转换为POCO，例如：

   internal class BookConverter : JsonConverter
   {
       public override bool CanWrite
       {
           get
           {
               return false;
           }
       }
       public override bool CanConvert(Type objectType)
       {
           return objectType == typeof(Book);
       }
       public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
       {
           var values = serializer.Deserialize<List<KeyValuePair<string, string>>>(reader);
           if (values == null)
               return existingValue;
           var book = existingValue as Book;
           if (book == null)
               book = new Book();
           // The following throws an exception on missing keys.  You could handle this differently if you prefer.
           book.BookId = values.Find(v => v.Key == "bookid").Value;
           book.Name = values.Find(v => v.Key == "name").Value;
           return book;
       }
       public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
       {
           throw new NotImplementedException();
       }
   }
   public class Result
   {
       public int resultnumber { get; set; }
       [JsonProperty("values")] 
       [JsonConverter(typeof(BookConverter))]
       public Book Book { get; set; }
   }
   public class Searchresult
   {
       public int resultscount { get; set; }
       public List<Result> results { get; set; }
   }
   public class RootObject
   {
       public Searchresult searchresult { get; set; }
   }
   

   然后

       var root = JsonConvert.DeserializeObject<RootObject>(json);
       var books = root.searchresult.results.Select(result => result.Book);
   

   在这里，我只实现了ReadJson，因为您的问题只询问反序列化。如果需要，可以类似地实现WriteJson。

3. 使用Linq to JSON将JSON加载到JObject的结构化层次结构中，然后使用Linq:将结果转换为Book的

       var books = 
           JObject.Parse(json).Descendants()
               .OfType<JProperty>()
               .Where(p => p.Name == "values")
               .Select(p => p.Value.ToObject<List<KeyValuePair<string, string>>>())
               .Select(values => new Book { Name = values.Find(v => v.Key == "name").Value, BookId = values.Find(v => v.Key == "bookid").Value })
               .ToList();