Json Deserializing not populating properties

Question

I'm deserializing a third party string like this:

{"status":4,"errors":[{"Duplicate Application":"Duplicate Application"}]}

I use my standard extension method:

public static T DeserializeJson<T>(string response)
    where T : class
{
    var s = new DataContractJsonSerializer(typeof(T));

    try {
        using (var ms = new MemoryStream()) {
            byte[] data = System.Text.Encoding.UTF8.GetBytes(response);
            ms.Write(data, 0, data.Length);
            ms.Position = 0;

            return (T)s.ReadObject(ms);
        }
    }
    catch {
        return default(T);
    }
}

The class I'm trying to deserialize to looks like this:

[DataContract]
public class ResponseProps
{
    [DataMember(Name = "status", Order = 0)]
    public string ResponseCode { get; set; }

    [DataMember(Name = "lead_id", Order=1)]
    public string LeadId { get; set; }

    [DataMember(Name = "price", Order=2)]
    public decimal Price { get; set; }

    [DataMember(Name = "redirect_url", Order = 3)]
    public string RedirectUrl { get; set; }

    [DataMember(Name = "errors", Order = 4)]
    public List<Dictionary<string, string>> Errors { get; set; }
}

I'm using a List of type Dictionary (string, string) for the Errors property because other types I've tried have broken the deserializer - this works in that the serializer no longer throws an exception.

However, I'm now trying to retrieve the data from Errors - I'm using this code:

var cr = XmlHelper.DeserializeJson<ResponseProps>(response);             

    var errorStore = new HashSet<string>();

    foreach (var dict in cr.Errors)
    {
        foreach (var kvp in dict)
        {
            errorStore.Add(kvp.Key + ": " + kvp.Value);
        }
    }

I've done various tests - the dict counts 1, but there are no kvp, so when the loop runs I get no messages.

I'm guessing this is again down to deserialization rather than incorrect looping, but I've not been able to fix it.

Anyone got any advice?

If you're working in c# 4.0 and so cannot use `UseSimpleDictionaryFormat` then possibly some of these answers would help: [Serialize `Dictionary` to JSON with DataContractJsonSerializer](https://stackoverflow.com/q/7498208/3744182). — dbc, Dec 18 '17 at 22:01
But if not, can you switch to [tag:json.net] or even `JavaScriptSerializer`? Is use of `DataContractJsonSerializer` a requirement? — dbc, Dec 18 '17 at 22:10

CodeFuller · Answer 1 · 2017-12-18T14:44:14.377

1

To be able to deserialize such dictionary, you should customize settings of DataContractJsonSerializer with UseSimpleDictionaryFormat set to true:

DataContractJsonSerializerSettings settings = new DataContractJsonSerializerSettings
{
    UseSimpleDictionaryFormat = true
};
var s = new DataContractJsonSerializer(typeof(T), settings);

By the way, do you have any reason to use DataContractJsonSerializer with your custom DeserializeJson<T>() method? You could do the same in one line of code with JSON.Net:

var obj = JsonConvert.DeserializeObject<ResponseProps>(str);

JSON.Net is also much more flexible and have a better performance than DataContractJsonSerializer.

edited Dec 18 '17 at 14:44

answered Dec 18 '17 at 14:37

CodeFuller

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This is the one and only instant I've used json - that's why I just wrote the extension. – John Ohara Dec 18 '17 at 14:49
I'm having trouble using the UseSimpleDictionaryFormat - showing an error. I'm using .Net 4.0 on this machine. – John Ohara Dec 18 '17 at 14:52
1

What is the error? Try using this code: `DataContractJsonSerializerSettings settings = new DataContractJsonSerializerSettings(); settings.UseSimpleDictionaryFormat = true;` – CodeFuller Dec 18 '17 at 14:54
I'm being told it's a syntax error - got the right reference and namespace. – John Ohara Dec 18 '17 at 14:59
It must be a version thing - cant see an overloaded constructor that includes settings – John Ohara Dec 18 '17 at 15:05
1

You're right, `DataContractJsonSerializerSettings` appeared only since 4.5 version of framework. Consider using Json.net if you can't upgrade. – CodeFuller Dec 18 '17 at 15:12

Json Deserializing not populating properties

1 Answers1