JSON.Net, JsonConvert.DeserializeObject - problems with deserialization

Question

When I am trying to deserialize my JSON with JSON.Net it gives me invalid values for JSON arrays.

I have simple JSON:

[
{
 "PhaseName": "Start",
 "Advices": ["Lorem ipsum dolor",
 "Lorem ipsum dolor",
 "Lorem ipsum dolor"]
},
{
 "PhaseName": "In Progress",
 "Advices": ["Lorem ipsum dolor",
 "Lorem ipsum dolor",
 "Lorem ipsum dolor"]
},
{
 "PhaseName": "Finish",
 "Advices": ["Lorem ipsum dolor",
 "Lorem ipsum dolor",
 "Lorem ipsum dolor"]
}

]

And a correspondent class in my code:

public class Advices
{
 public string PhaseName { get; set; }
 public List<string> AdvicesList { get; set; }
}

And a veriable that represents an array of Advices objects:

public class MyAdvices
{
 private Advices[] MyAdvicesArrays;
....

So when I am trying to deserialize my JSON like that:

MyAdvicesArrays= JsonConvert.DeserializeObject<Advices[]>(sMyJSON));

JSON.Net populates "Phase Name" property of each object in my MyAdvicesArrays array with correct value but Advices array of each object is invalid: "Could not evaluate expression" if you check them in runtime. I don't get it. What I've done wrong?

Answer 1

Your json is not valid according to the entities.

In your type change AdvicesList to Advices.

public List<string> AdvicesList { get; set; }

Change it to

public List<string> Advices { get; set; }

• Alex: "Advices" in my example supposed to be an object with string property and array property, how could it be List<string>?

Answer 2

No, you're JSON is incorrect as is you Class.

First change your JSON to this:

{
 phases:[
 {
 "PhaseName": "Start",
 "Advices": ["Lorem ipsum dolor",
 "Lorem ipsum dolor",
 "Lorem ipsum dolor"]
 },
 {
 "PhaseName": "In Progress",
 "Advices": ["Lorem ipsum dolor",
 "Lorem ipsum dolor",
 "Lorem ipsum dolor"]
 },
 {
 "PhaseName": "Finish",
 "Advices": ["Lorem ipsum dolor",
 "Lorem ipsum dolor",
 "Lorem ipsum dolor"]
 }
 ]
}

Notice before you weren't declaring you JSON object correctly. Also you need a property for the array.

Now you'll need two classes:

public class AnythinYouWant{
 public List<Phase> Phases{get;set;}
}
public class Phase{
 public string PhaseName{get;set;}
 public List<string> Advices{get;set;}
}

Notice how the first class is for the top level JSON object. The name can be whatever you want. But any property needs to match the name.

• Alex: Thanks, sounds logical. So does it mean that I cannot have unnamed array of objects in JSON like in my example? [ { "example": 1, "example2": "TestName" }, { "example3": 1, "example4": "TestName" } ]
• andy: no you can't, because your json object must always begin with {}, you can't declare it with []. After the initial {} you have to have a property to assign your first array.

Answer 3

All I did to get this working was to change the definition of the Advices class:

public class Advice
{
 public string PhaseName { get; set; }
 public List<string> Advices { get; set; }
}

I changed the class name to just Advice and AdvicesList property to Advices.

• Alex: I don't understand, what have you changed except for class name and property name? The class definition is still the same.