Deserialize JSON With Delimited String Directly to List Using TypeConverter

Question

User-691759321 posted

So, I have a JSON value as a string:

"[{"Purpose":"Internal; Product Selection"},{"Purpose":"Product Selection; Web"},{"Purpose":"Internal; Product Selection"}]"

I have a class designed to deserialize the JSON to (note this is a simplified class structure).

using Newtonsoft.Json;
using System.Collections.Generic;
using System.ComponentModel;

public class Attribute
{
	public string Purpose { get; set; }
}

I am using Newtonsoft.Json version 9.  Each Attribute.Purpose field is populated with semi-colon delimited list after the deserialization process.  What I would prefer is to have Purpose be a List<string>.  I did try to take in the value as a string and have a read-only property convert the string to a list.  This works but is slow. 

using Newtonsoft.Json;
using System.Collections.Generic;
using System.Linq;

public class Attribute
{

    [JsonProperty("Purpose")]
    public string _Purpose { get; set; }

    [JsonIgnore]
    public List<string> Purpose {
        get
        {
            return this._Purpose.Split(';').Select(x => x.Trim()).ToList();
        }
    }
}

I would like to use a TypeConverter but cannot seem to find one that work.  I should mention that I am using Sitecore through a Solr ContentSearchManager query.  Sitecore has provided some custom converters for index fields which do exactly what I want, however this is not an index field. The converter I use on the index field is Sitecore.ContentSearch.Converters.IndexFieldEnumerableConverter.  I am looking for some way to handle this with standard .NET libraries or Newtonsoft.

Any ideas?

Answer 1

User475983607 posted

The ideal solution is fixing the JSON format.

{"Purpose": ["Internal", "Product Selection"]}

Answer 2

User-691759321 posted
The simple response is that changing the format of Json is not an option. I know it is improper for the data type but I do not have control to fix it.

Answer 3

User753101303 posted

Hi,

From a quick look it seems you could customize how this property is serialized/deserialized using https://www.newtonsoft.com/json/help/html/CustomJsonConverterGeneric.htm doing a string.Split when reading and a string.Join when writing.

Answer 4

User-691759321 posted

While an interesting idea I am not sure how this would translate to my example.  The code in that link seems to apply for custom classes only.  Almost every field in my Product class is a string.  I am not sure if a custom converter would know how to distinguish between a delimited list and a description that just happens to contain the same delimiter.  

Answer 5

User753101303 posted

You can put this attribute on the Purpose property only. For example :

using Newtonsoft.Json;
using System;
using System.Collections.Generic;
using System.Linq;

namespace ConsoleDemo
{
    public class DelimitedStringConverter : JsonConverter<List<string>>
    {
        public override void WriteJson(JsonWriter writer, List<string> value, JsonSerializer serializer)
        {
            throw new NotImplementedException();
        }
        public override List<string> ReadJson(JsonReader reader, Type objectType, List<string> existingValue, bool hasExistingValue, JsonSerializer serializer)
        {
            string s = (string)reader.Value;
            if (string.IsNullOrEmpty(s))
            {
                return new List<string>();
            }
            return s.Split(';').Select(x => x.Trim()).ToList();
        }
    }

    class Program
    {
        class Data
        {
            public string Name { get; set; }
            [JsonConverter(typeof(DelimitedStringConverter))]
            public List<string> Purpose { get; set; }
        }
        static void Main()
        {
             var str = @"{""Name"":""a; b"",""Purpose"":""a; b""}";
             var data = JsonConvert.DeserializeObject<Data>(str);
             Console.WriteLine(data.Name);
             foreach (string value in data.Purpose)
             {
                 Console.WriteLine("-{0}-", value);
             }
        }
    }
}

shows :

a; b
-a-
-b-

Answer 6

User-691759321 posted

I could not use JsonConverter<List<string>> because we are still using version 9 of Newtonsoft.Json and it does not support it.  I was able to take that out and use the generic JsonConverter override to achieve what I wanted.  

Thanks!