Newtonsoft.Json.JsonSerializationException Message=Cannot deserialize the current JSON object

Question

here the ex

Newtonsoft.Json.JsonSerializationException
  Message=Cannot deserialize the current JSON object (e.g. {"name":"value"}) into type 'System.Collections.Generic.List`1[CCSN.Models.Patient]' because the type requires a JSON array (e.g. [1,2,3]) to deserialize correctly.
To fix this error either change the JSON to a JSON array (e.g. [1,2,3]) or change the deserialized type so that it is a normal .NET type (e.g. not a primitive type like integer, not a collection type like an array or List<T>) that can be deserialized from a JSON object. JsonObjectAttribute can also be added to the type to force it to deserialize from a JSON object.
Path '0', line 1, position 5.

in this line to get patient

return JsonConvert.DeserializeObject<TEntity>(json);

  public static async Task<TEntity> Get<TEntity>(string url)
        {
            HttpClientHandler clientHandler = new HttpClientHandler();
            clientHandler.ServerCertificateCustomValidationCallback = (sender, cert, chain, sslPolicyErrors) => { return true; };

            HttpClient client = new HttpClient(clientHandler);

            var response = await client.GetAsync(url);
            var json = await response.Content.ReadAsStringAsync();
            
            return JsonConvert.DeserializeObject<TEntity>(json);
        }

is the error from not converting?

and how can i convert to object or json

this is the service to get Patient

public static async Task<IEnumerable<Patient>> GetUserPatients()
        {
            var url = await firebaseClient
                     .Child($"Specalists/406707265/Patients").BuildUrlAsync();
 
            var result = await Helper.Get<List<Patient>>(url);
            return result ;
            
        }

Changed the Get type, to try to match the json

    public static async Task<IEnumerable<Patient>> GetUserPatients()
        {
            var url = await firebaseClient
                     .Child($"Specalists/406707265/Patients").BuildUrlAsync();
            var patientsDict = await Helper.Get<Dictionary<string, Patient>>(url);
            var result = patientsDict.Values.ToList();
            return result ;
            
        }

Answer 1

The back and forth in comments has gotten unwieldy. Here is a community wiki showing the status of resolving this.

Exception:

Newtonsoft.Json.JsonSerializationException
  Message=Cannot deserialize the current JSON object (e.g. {"name":"value"}) into type 'System.Collections.Generic.List`1[CCSN.Models.Patient]' because the type requires a JSON array (e.g. [1,2,3]) to deserialize correctly.
To fix this error either change the JSON to a JSON array (e.g. [1,2,3]) or change the deserialized type so that it is a normal .NET type (e.g. not a primitive type like integer, not a collection type like an array or List<T>) that can be deserialized from a JSON object. JsonObjectAttribute can also be added to the type to force it to deserialize from a JSON object.
Path '0', line 1, position 5.

NOTE: Exception says is trying to deserialize into

'System.Collections.Generic.List`1[CCSN.Models.Patient]'

In c# that would be a List<Patient>.

Statement in PatientServices.Addpat in which exception is believed to occur:

        var x = await firebaseClient
                .Child($"Specalists/406707265/Patients")
                .PostAsync(new Patient(patient));

Those statements must lead to this - the lower-level line in which exception occurs:

    return JsonConvert.DeserializeObject<TEntity>(json);

---

1. json (skipping most of it):

{
  "0":{
   "Appointments":[
    {"AppointmentDate":"2022-04-12T00:00:00+03:00"
    }
   ],
   "ID": "0",
   "PatientName": "Ghaidaa"
  },

 "-N-tZ6hbyPpWOWeoo9o4": {
   "ID": "45455184",
   "PatientName": "sgagaga"
  }
}

2. TEntity:

Based on the error message, TEntity is presumably List<Patient>.

---

The problem is that the json (shown above) isn't in the expected format. It is a dynamic object with keys "0", "1", "-N-tZ6hbyPpWOWeoo9o4".

The calling code is expecting a json array, which would look like this:

[ {
   "Appointments":[
    {"AppointmentDate":"2022-04-12T00:00:00+03:00"
    }
   ],
   "ID": "0",
   "PatientName": "Ghaidaa"
  },

  {
   "ID": "45455184",
   "PatientName": "sgagaga"
  }
]

The difference is easiest to see by examining the beginning and end of the json.

---

One way to fix is to deserialize to a Dictionary. Then extract the values of the Dictionary into a list.

Find code that looks something like the line below. Replace:

    var patients = await Helper.Get<List<Patient>>(url);

With:

    var patientsDict = await Helper.Get<Dictionary<string, Patient>>(url);
    var patients = patientsDict.Values;

Or depending on how you use it, might change the last line to:

    var patients = patientsDict.Values.ToList();

---

An ALTERNATIVE way to fix is to change the server side, so that it sends an array of Patients instead of a dynamic object.

--- Making that change is beyond the scope of this answer ---