Deserializing JSON text to an object in C#

Question

I have the following class:

public class DeviceInfo
{
    public string? ip { get; set; }
    public string? deviceKey { get; set; }
    public long time { get; set; }
    public string? version { get; set; }
    public int faceCount { get; set; }
    public int personCount { get; set; }
}

On the other hand, I have this json string:

{
   "ip": "192.168.0.146",
   "deviceKey": "A34CC830D348437A",
   "time": "1741375392869",
   "version": "1.41.9.7",
   "faceCount": "0",
   "personCount": "0"
}

When executing:

JsonSerializerOptions? options = customImplementation ? new JsonSerializerOptions
{
    TypeInfoResolver = new DefaultJsonTypeInfoResolver
    {
        Modifiers = { JsonImplementationAttribute.ReadAttributeFromTypeInfo }
    }
} : null;
JsonSerializer.Deserialize<DeviceInfo>(json, options);

I got this error:

Exception: System.Text.Json.JsonException: The JSON value could not be converted to System.Int64. Path: $.time | LineNumber: 0 | BytePositionInLine: 75. ---> System.InvalidOperationException: Cannot get the value of a token type 'String' as a number. at System.Text.Json.ThrowHelper.ThrowInvalidOperationException_ExpectedNumber(JsonTokenType tokenType) at System.Text.Json.Utf8JsonReader.TryGetInt64(Int64& value) at System.Text.Json.Utf8JsonReader.GetInt64() at System.Text.Json.Serialization.Metadata.JsonPropertyInfo1.ReadJsonAndSetMember(Object obj, ReadStack& state, Utf8JsonReader& reader) at System.Text.Json.Serialization.Converters.ObjectDefaultConverter1.OnTryRead(Utf8JsonReader& reader, Type typeToConvert, JsonSerializerOptions options, ReadStack& state, T& value) at System.Text.Json.Serialization.JsonConverter1.TryRead(Utf8JsonReader& reader, Type typeToConvert, JsonSerializerOptions options, ReadStack& state, T& value, Boolean& isPopulatedValue) at System.Text.Json.Serialization.JsonConverter1.ReadCore(Utf8JsonReader& reader, JsonSerializerOptions options, ReadStack& state) --- End of inner exception stack trace --- at System.Text.Json.ThrowHelper.ReThrowWithPath(ReadStack& state, Utf8JsonReader& reader, Exception ex) at System.Text.Json.Serialization.JsonConverter1.ReadCore(Utf8JsonReader& reader, JsonSerializerOptions options, ReadStack& state) at System.Text.Json.JsonSerializer.ReadFromSpan[TValue](ReadOnlySpan1 utf8Json, JsonTypeInfo1 jsonTypeInfo, Nullable1 actualByteCount)
at System.Text.Json.JsonSerializer.ReadFromSpan[TValue](ReadOnlySpan1 json, JsonTypeInfo1 jsonTypeInfo) at System.Text.Json.JsonSerializer.Deserialize[TValue](String json, JsonSerializerOptions options) at Modules.Integration.Extensions.JsonExtensions.ToObject[T](Object o, Boolean customImplementation) in C:\WorkingFolder\Projects\Desytec\Development\Desytec-Security-Platform\Web\Modules\Modules.Integration\Extensions\JsonExtensions.cs:line 29 at AdmsServer.Services.PassDeviceService.SaveOptions(String serialNumber) in C:\WorkingFolder\Projects\Desytec\Development\Desytec-Security-Platform\Web\Devices\AdmsServer\Services\PassDeviceService.cs:line 237 at AdmsServer.Controllers.Drivers.API.PassController.Heartbeat(DeviceInfo device) in C:\WorkingFolder\Projects\Desytec\Development\Desytec-Security-Platform\Web\Devices\AdmsServer\Controllers\Drivers\API\PassController.cs:line 83

What wrong thing do you see here?

Regards

time is declared as a longin the class, but it's a string in the json. faceCount and personCount will likely fail for the same reason. — Alejandro
– Alejandro, Commented Mar 7 at 19:43
It is a json string transmitted over Internet so obviously all members are string. How can this be faced then? — jstuardo
– jstuardo, Commented Mar 7 at 19:53
JSON supports both strings and numbers (and a few other types), regardless of how it's transmited. Since the value is enclosed in quotes, it means it's a string (a number won't have them). — Alejandro
– Alejandro, Commented Mar 7 at 19:59

Ryan Wilson · Accepted Answer · 2025-03-07 19:51:13Z

2

You can utilize the built in JsonSerializerOptions and set the NumberHandling Property, as its not set to read strings as numbers by default, you can change that like so:

public class Test
{
    public long time {get; set;}    
}

var o = new System.Text.Json.JsonSerializerOptions();
o.NumberHandling = System.Text.Json.Serialization
                .JsonNumberHandling.AllowReadingFromString;
        
string json = "{\"time\": \"99999000\"}";
var test = System.Text.Json.JsonSerializer.Deserialize<Test>(json, o);
Console.WriteLine(test.time);

Here's a link to a DotNet Fiddle: DotNetFiddle

answered Mar 7 at 19:51

Ryan Wilson

10.9k3 gold badges23 silver badges46 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

Deserializing JSON text to an object in C#

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related