将对象数组反序列化为 C# 类在 Xamarin.Forms App 中返回 null

Question

I have this class in my App:

public class Control
{
    public int Id { get; set; }
    public string Name { get; set; }
    public string ControlDescription { get; set; }
    public string ControlExceptionText { get; set; }
    public string Color { get; set; }
    public double DataRetrieving_Frequency { get; set; }
    public double delay_Factor { get; set; }
    public Boolean Disabled { get; set; }
}

My json string is :

var result = 
"[
{\"id\":16,\"name\":\"trest\",\"controlDescription\":null,\"controlExceptionText\":null,\"color\":\"#abdb2c\",\"dataRetrieving_Frequency\":0.0,\"delay_Factor\":0.0,\"disabled\":false},
{\"id\":15,\"name\":\"test\",\"controlDescription\":null,\"controlExceptionText\":null,\"color\":\"#441fed\",\"dataRetrieving_Frequency\":1440.0,\"delay_Factor\":10.0,\"disabled\":false},
{\"id\":14,\"name\":\"Powershell\",\"controlDescription\":\"text. \",\"controlExceptionText\":\"exception.\",\"color\":\"#ad89d7\",\"dataRetrieving_Frequency\":1440.0,\"delay_Factor\":10.0,\"disabled\":false}
]"

and I want to deserialize this json to fit my Control class . So I did this to convert my Deserializeobject:

List<Control> test = JsonConvert.DeserializeObject<List<Control>>(result);

the problem is that test returns null .

Any idea?!

Update:

• This code works fine in my other app, but not in Xamarin.Form app.
• Tried also to append @ to the begining of the JSON string but get this error

Unexpected character encountered while parsing value @.

Update:

I'm using Xamarin Live Player to review my app, and Perhaps the problem is related to this, because many developers are complaining about serializing and deserializing bugs when using Live Player.

Answer 1

Your json string is not correct.

JSON data is written as name/value pairs.

A name/value pair consists of a field name (in double quotes), followed by a colon, followed by a value: "name":"John"

Remove backslashes from your json string. For the future you can check correctness of your json string here

Answer 2

Deserialization works with this string format:

So to answer your question: You need a valid JSON string to make the deserialization. Start with a @ at the top, and replace all \\" into double quotes.

Update edit: @ sign should be outside of the string, it's not part of the JSON string, it's just an indicator that your string will be multiline.

Answer 3

This works fine for me. Here's another example I have tried so far without deserialization. I'm getting a response as a JSON file. my JSON looks like this.

..and I did this to get each elements from the JSON. and I have fit those elements to the monkeys List.

using (JsonDocument document = JsonDocument.Parse(response, options))
            {
                Grid grid = new Grid();
                Monkeys = new List<Monkey>();
                foreach (JsonElement element in document.RootElement.EnumerateArray())
                {
                    if (element.TryGetProperty("id", out JsonElement id)&&(element.TryGetProperty("end", out JsonElement end) )
                        && (element.TryGetProperty("time", out JsonElement time) && (element.TryGetProperty("description", out JsonElement description)
                        && (element.TryGetProperty("start", out JsonElement start) && (element.TryGetProperty("date", out JsonElement date))))))
                    {    
                        Monkeys.Add(new Monkey
                        {
                            Time=time.ToString(),
                            Start = start.ToString(),
                            End =end.ToString(),
                            Description = description.ToString()
                        });
                        BindingContext = this;
                    }
                }
            }

and this is my monkey class

public class Monkey
    {
        public string Time { get; set; }
        public string Start { get; set; }
        public string End { get; set; }
        public string Description { get; set; }
        public string ImageUrl { get; set; }

        public override string ToString()
        {
            return Start;
        }
    }