Question 169443 in Json Question posted in
Our archive of expertly curated questions and answers provides insights and solutions to common problems related to this popular data interchange format. From parsing and manipulating JSON data to integrating it with various programming languages and web services, our archive has got you covered. Start exploring today and take your JSON skills to the next level

Can C# deserialize JSON with dynamic property type?

The API currently return two types of json string (the type field always be string but the data field may be string or list or int):

For example Type 1:

{
    "type": "error",
    "data": "error message"
}

Type 2:

{
    "type": "success",
    "data": [
        {
            "id": 1,
            "title": "tortor at auctor urna nunc",
            "content": "Lorem ipsum dolor sit amet, consectetur adipiscing elit."
        },
        {
            "id": 2,
            "title": "gravida rutrum quisque non tellus",
            "content": "Lorem ipsum dolor sit amet, consectetur adipiscing elit."
        }
        ]
}

I have the following class for mapping the json string:

class ResponseData
{
    [JsonPropertyName("type")]
    public string Type { get; set; }

    [JsonPropertyName("data")]
    public string Data { get; set; }
}

I would like to deserialize the json to ResponseData and print out the text in data field, for example:

var response = await httpClient.GetAsync(url);
var responseData = await response.Content.ReadFromJsonAsync<ResponseData>();
Debug.WriteLine(responseData.Data);

If the API returns the json type 1, the code works fine. but if it returns the json type 2, it throws the following error message:

Exception thrown: 'System.Text.Json.JsonException' in System.Private.CoreLib.dll
The JSON value could not be converted to System.String. Path: $.data | LineNumber: 0 | BytePositionInLine: 32.: Error

Any idea to solve this issue?
Thanks.

I would expect if the API returns the json type 2, at least the following json string can be saved into responseData.Data as string:

"[
    {
        "id": 1,
        "title": "tortor at auctor urna nunc",
        "content": "Lorem ipsum dolor sit amet, consectetur adipiscing elit."
    }
]"

so that I can deserialize the responseData.Data json string into another object

var dataList = JsonSerializer.Deserialize<DataList>(responseData.Data);
Tags:

2

Answers


  1. 0

    The problem is in both cases you’re trying to deserialize "data" to a string (because you’ve defined the property Data in your ResponseData class to be of type string), but in the second case "data" is a json array, which can’t be automatically converted to a string.

    I’m not sure your design is the optimal approach in the first place if I may say so, but if you want to get it working as is, more or less, you could change Data’s type to obejct.

    Here is a quick demo of the idea using Newtonsoft:

    string example1 = @"{
    ""type"": ""error"",
    ""data"": ""error message""
}";

string example2 = @"{
    ""type"": ""success"",
    ""data"": [
        {
            ""id"": 1,
            ""title"": ""tortor at auctor urna nunc"",
            ""content"": ""Lorem ipsum dolor sit amet, consectetur adipiscing elit.""
        },
        {
            ""id"": 2,
            ""title"": ""gravida rutrum quisque non tellus"",
            ""content"": ""Lorem ipsum dolor sit amet, consectetur adipiscing elit.""
        }
        ]
}";

var response1 = Newtonsoft.Json.JsonConvert.DeserializeObject<ResponseData>(example1);
Console.WriteLine(response1.Data.ToString());

var response2 = Newtonsoft.Json.JsonConvert.DeserializeObject<ResponseData>(example2);
Console.WriteLine(response2.Data.ToString());

class ResponseData
{
    [JsonPropertyName("type")]
    public string Type { get; set; }

    [JsonPropertyName("data")]
    public object Data { get; set; }
}
    Login or Signup to reply.
  2. 0

    you can try this code

        var json = await response.Content.ReadAsStringAsync();

    var jn = JsonNode.Parse(json).AsObject();
    ResponseData responseData = jn.Deserialize<ResponseData>();

    if (responseData.Type == "success")
        responseData.Data = jn["data"].Deserialize<List<Datum>>();
    else
        responseData.ErrorMessage = jn["data"].GetValue<string>();

    classes

    public partial class ResponseData
{
    [JsonPropertyName("type")]
    public string Type { get; set; }

    public string ErrorMessage { get; set; }

    public List<Datum> Data { get; set; }
}

public partial class Datum
{
    [JsonPropertyName("id")]
    public long Id { get; set; }

    [JsonPropertyName("title")]
    public string Title { get; set; }

    [JsonPropertyName("content")]
    public string Content { get; set; }
}
    Login or Signup to reply.
Please signup or login to give your own answer.

Back To Top
Search