why grpc unhandled (StatusCode="Unavailable") ,unknown when invoking a method generated from a proto file?

Question

# Description of the problem When I want to call the Grpc service on the client side, it throws this exception, where is my problem?#(Exception =\> StatusCode="Unavailable", Error connecting to subchannel"))

# Model In this example, my model code is connected to the database, but it does not call any data for me

[ProtoContract]
    public class Person
    {
        [ProtoMember(1)]
        public int PersonId { get; set; }

        [ProtoMember(2)]
        public string FirstName { get; set; }

        [ProtoMember(3)]
        public string LastName { get; set; }
    }

Service Proto :

public class PersonInfoService : PersonInformationService.PersonInformationServiceBase
    {
        private readonly IPersonService _service;
        private readonly IMapper _mapper;
        public PersonInfoService(IPersonService service, IMapper mapper)
        {
            _service = service;
            _mapper = mapper;
        }

        public async override Task<Persons> GetAllPersonList(Empty request, ServerCallContext context)
        {
                var person = await _service.GetPersonListAsync();
                Persons response = new Persons();
                foreach (Person item in person)
                {
                    response.Items.Add(_mapper.Map<PersonInfo>(item));
                }
                return await Task.FromResult(response);
            }
        }

Proto : proto document:

service PersonInformationService {

  rpc GetAllPersonList (Empty) returns (Persons) {}

message Empty{}

message PersonInfo{
    int32 personId = 1;
    string firstName = 2;
    string lastName = 3;
}
message Persons {
  repeated PersonInfo items = 1;
}

Answer 1

it's enough ! Install the GRpc.AspNetCore.Server.Reflection package and add the service to the Program class and add its middleware. Finally, by using Postman, you can debug the proto service and solve the service problem.

using GrpcService_Test.AppDBContext;
using GrpcService_Test.Interface;
using GrpcService_Test.Services;
using Microsoft.EntityFrameworkCore;

var builder = WebApplication.CreateBuilder(args);

// Additional configuration is required to successfully run gRPC on macOS.
// For instructions on how to configure Kestrel and gRPC clients on macOS, visit https://go.microsoft.com/fwlink/?linkid=2099682

// Add services to the container.
builder.Services.AddGrpc();
builder.Services.AddGrpcReflection();
builder.Services.AddTransient<IPersonService, PersonService>();

builder.Services.AddDbContext<AppDbContext>(opt =>
{
    opt.UseSqlServer(builder.Configuration.GetConnectionString("SqlServer"));
});

builder.Services.AddCors(options => {
    options.AddPolicy("cors", policy => {
        policy.AllowAnyMethod().AllowAnyHeader().AllowAnyOrigin().WithExposedHeaders("Grpc-Status", "Grpc-Message", "Grpc-Encoding", "Grpc-Accept-Encoding");
    });
});

builder.Services.AddAutoMapper(typeof(Program).Assembly);

var app = builder.Build();

app.UseHttpsRedirection();
app.UseRouting();

app.UseCors();

// Configure the HTTP request pipeline.
app.MapGrpcService<TestService>();
app.MapGrpcService<GetObjectValueService>();
app.MapGrpcService<PersonInfoService>();
app.MapGrpcReflectionService();
app.MapGet("/", () => "Communication with gRPC endpoints must be made through a gRPC client. To learn how to create a client, visit: https://go.microsoft.com/fwlink/?linkid=2086909");

app.Run();

Using this link, you can see how to test grpc in my post. [

https://learning.postman.com/docs/sending-requests/grpc/first-grpc-request/

]1