C#•3mo ago

MediatR - System.Text.Json.JsonException: 'S' is an invalid start of a value.

I have a project with Clean Architecture and MediatR. My API gets the request fine and the command is created with correct data. In this case my tests passes Email = "test@test.com"

var command = new CreateUserCommand(userReq.Email);
var createUserResult = await mediator.Send(command);

My command:
public record CreateUserCommand(string Email) : IRequest<ErrorOr<User>>;

My handler:
  public async Task<ErrorOr<User>> Handle(CreateUserCommand command, CancellationToken cancellationToken)
    {
        var user = await _userRepository.CreateUser(new User(){Email = command.Email});
        await _unitOfWork.CommitChangesAsync();
        return user;
    }

I Register my MediatR like this:
 services.AddMediatR(options =>
        {
            // options.RegisterServicesFromAssemblyContaining(typeof(DependencyInjection));
            options.RegisterServicesFromAssembly(typeof(DependencyInjection).Assembly);
        });

var command = new CreateUserCommand(userReq.Email);
var createUserResult = await mediator.Send(command);

My command:
public record CreateUserCommand(string Email) : IRequest<ErrorOr<User>>;

My handler:
  public async Task<ErrorOr<User>> Handle(CreateUserCommand command, CancellationToken cancellationToken)
    {
        var user = await _userRepository.CreateUser(new User(){Email = command.Email});
        await _unitOfWork.CommitChangesAsync();
        return user;
    }

I Register my MediatR like this:
 services.AddMediatR(options =>
        {
            // options.RegisterServicesFromAssemblyContaining(typeof(DependencyInjection));
            options.RegisterServicesFromAssembly(typeof(DependencyInjection).Assembly);
        });

However, my Handler is never invoked. Directly after

mediator.Send(command);

mediator.Send(command);

I get the following error System.Text.Json.JsonException 'S' is an invalid start of a value. Path: $ | LineNumber: 0 | BytePositionInLine: 0. at System.Text.Json.ThrowHelper.ReThrowWithPath(ReadStack& state, JsonReaderException ex) at System.Text.Json.Serialization.JsonConverter`1.ReadCore(Utf8JsonReader& reader, JsonSerializerOptions options, ReadStack& state) Any pointers or ideas what the cause might be?

4 Replies

Rizell•3mo ago

Issue is solved. I had just forgotten to implement the : IRequestHandler<CreateUserCommand, ErrorOr<User>> on my Handler class

Unknown User•3mo ago

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MODiX•3mo ago

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Unknown User•3mo ago

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MediatR - System.Text.Json.JsonException: 'S' is an invalid start of a value.