CODEWITHSUNDEEP
c#asp.netjsonlinq
user3723240
user3723240

Reputation: 393

How to convert list to json

I have a function that connects to the database and executes a query and returns the data, now I am trying to call that function and convert the data to JSON

public List<string> getListItems()
        {
            AirportClass airport = new AirportClass();
            return JArray.Parse(airport.getListItems());
            return airport.getListItems();
        }

I keep getting this error 'The best overloaded method match for 'Newtonsoft.Json.Linq.JArray.Parse(string)' has some invalid arguments'

What am I doing wrong?

I have also tried the following:

public List<string> getListItems()
        {
            AirportClass airport = new AirportClass();
            JavaScriptSerializer JsonConvert = new JavaScriptSerializer();
            JsonConvert.Serialize(airport.getListItems());
            return JsonConvert;
        }

but this also gives me an error 'Cannot implicitly convert type 'JavaScriptSerializer' to Generic.List'

I also tried:

public List<string> getListItems()
        {
            AirportClass airport = new AirportClass();
            JsonSerializer JsonConvert = new JsonSerializer();
            JsonConvert.Serialize(getListItems());
            return airport.getListItems();
        }

but this gives me another error 'No overload for method 'Serialize' takes 1 arguments'

Upvotes: 2

Views: 15898

Answers (1)

AaronLS
AaronLS

Reputation: 38367

You are not saving the return of the Serialize result:

JsonConvert.Serialize(airport.getListItems());
return JsonConvert;

Corrected with correct return type. Converting from object to JSON produces a single string encoded as a JSON array, so your return type is string, not List<string>

public string getListItems() {
  AirportClass airport = new AirportClass();
  //removed JsonConvert declaration cause that would hide the JsonConvert class, don't name variables the same name as classes
  string result = JsonConvert.SerializeObject(airport.getListItems());
  return result;
}

It does not produce a List, to do that you'd need to serialize each item seperately, which is different from serializing a list. In that case you'd just use a loop to call Serialize on each item.

Upvotes: 3

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