从有角度的前端路由到 ASP.NET Core 3.1 后端

问题描述

So here is my backend .csproj。我正在做一个前端水疗，以角度连接到我在内存数据库中的后端。 I can connect to my database from the URL of my back end application like in the image. 我也可以通过这个 postman sucessfull responses 提出邮递员请求并获得 header ......到目前为止一切都很好。在我的前端有一个问题。我有我的前端角度 service package with the url i use in postman。 in my component i call this method to connect to my service. 不知何故，我无法获得我在邮递员中执行获取请求时获得的“行程”列表。我几乎 80% 确定错误在后端，因为我可以在其他后端应用程序中获取请求。所以我要把我的后端代码放在这里。

我的程序.cs

public class Program
{
    public static void Main(string[] args)
    {
        var host = CreateHostBuilder(args).Build();

        using (var scope = host.Services.CreateScope())
        using (var context = scope.ServiceProvider.GetService<AppDbContext>())
        {
            context.Database.EnsureCreated();
        }

        host.Run();
    }

    public static IHostBuilder CreateHostBuilder(string[] args) =>
        Host.CreateDefaultBuilder(args)
            .ConfigureWebHostDefaults(webBuilder =>
            {
                webBuilder.UseStartup<Startup>();
            });
}

launchSettings.json

我的startup.cs

public class Startup
{
    public IConfiguration Configuration { get; }

    public Startup(IConfiguration configuration)
    {
        Configuration = configuration;
    }

    public void ConfigureServices(IServiceCollection services)
    {
        services.AddMemoryCache();


        services.AddControllers().ConfigureApiBehaviorOptions(options =>
        {


        });

        services.AddDbContext<AppDbContext>(options =>
        {
            options.UseInMemoryDatabase(Configuration.GetConnectionString("memory"));
        });


        services.AddScoped<ITripRepository,TripRepository>();
        services.AddScoped<ITripService,TripService>();
        services.AddScoped<IUnitOfWork,UnitOfWork>();
        services.AddAutoMapper(typeof(Startup));


    }

    public void Configure(IApplicationBuilder app,IWebHostEnvironment env)
    {
        if (env.IsDevelopment())
        {
            app.UseDeveloperExceptionPage();
        }


        app.UseRouting();

        app.UseAuthorization();

        app.UseEndpoints(endpoints =>
        {
            endpoints.MapControllers();
        });
    }
}

}

我的获取控制器：

[HttpGet]
    [ProducesResponseType(typeof(List<TripDTO>),200)]
    public async Task<IEnumerable<TripDTO>> GetAllAsync()
    {
        var trips = await _tripService.ListAsync();
        var dtos = _mapper.Map<IEnumerable<Trip>,IEnumerable<TripDTO>>(trips);

        return dtos;
    }

编辑： 我在尝试获取的列表中执行前端 console.log 时遇到的错误是 enter image description here

EDIT2：AppDbContext 后端

public class AppDbContext : DbContext
{
    public DbSet<Trip> Trips { get; set; }
   

    public AppDbContext(DbContextOptions<AppDbContext> options) : base(options) { }

    protected override void OnModelCreating(ModelBuilder builder)
    {
        base.OnModelCreating(builder);
        
        builder.Entity<Trip>().ToTable("Trips");
        builder.Entity<Trip>().HasKey(p => p.Id);
        builder.Entity<Trip>().Property(p => p.Id).Isrequired().ValueGeneratedOnAdd();
        builder.Entity<Trip>().Property(p => p.Key).Isrequired().HasMaxLength(10);
        builder.Entity<Trip>().Property(p => p.IsEmpty).Isrequired();
        builder.Entity<Trip>().Property(p => p.Orientation).Isrequired();
        builder.Entity<Trip>().Property(p => p.LineKey).Isrequired().HasMaxLength(10);
        builder.Entity<Trip>().Property(p => p.PathKey).Isrequired().HasMaxLength(10);
        builder.Entity<Trip>().Property(p => p.IsGenerated).Isrequired();
        builder.Entity<Trip>().Property(p => p.PassingTimes)
        .HasConversion(
        v => JsonConvert.SerializeObject(v),v => JsonConvert.DeserializeObject<List<PassingTime>>(v));

        builder.Entity<Trip>().HasData
        (
            new Trip { Id = 100,Key="Trip:344",IsEmpty=false,Orientation=false,LineKey="Line:444",PathKey="Path:344",IsGenerated=true },// Id set manually due to in-memory provider
            new Trip { Id = 1200,Key="Trip:1344",LineKey="Line:2444",PathKey="Path:3424",IsGenerated=true }
        );

   
    }
}

}

编辑 3：

HTML 
    <!DOCTYPE html>
<html>

<body>
  <h4>List of Trips</h4>
  <div class="list row">
    <div class="col-md-6">
      <ul class="list-group">
        <li class="list-group-item" *ngFor="let trip of trips; let i = index" [class.active]="i == currentIndex" (click)="setActiveTrip(trip,i)">
          {{ trip.key }}
        </li>
      </ul>
    </div>
    <div *ngIf="!currentTrip">
      <br />
      <p>Please click on a trip to see the details...</p>
    </div>
    <div class="col-md-6">
      <div *ngIf="currentTrip">
        <h4>Selected Trip Details</h4>
        <div>
            <div>
              <label><strong>Key:</strong></label> {{ currentTrip.key }}
            </div>
            
        </div>
      </div>
    </div>
  </div>
</body>

</html>

component.cs

    import { Component,OnInit } from '@angular/core';
import { TripService } from 'src/app/masterdataviagem/services/trip-service';

@Component({
  selector: 'app-tripslist',templateUrl: './tripslist.component.html',styleUrls: ['./tripslist.component.css']
})
export class TripslistComponent implements OnInit {

  trips: any;
  currentTrip: any = null;
  currentIndex = -1;
  key = '';
  tripsList:any;

  constructor(private tripService:TripService) { this.tripsList=this.tripService.getAll()}

  ngOnInit(): void {
    this.retrieveTrips();
   
   
  }

  retrieveTrips() {
   this.trips= this.tripService.getAll().subscribe(
    data => {
      this.trips = data;
      console.log(data);
    },error => {
      console.log(error);
    });
   console.log(this.trips);
  }

  refreshList() {
    this.retrieveTrips();
    this.currentTrip = null;
    this.currentIndex = -1;
  }

  setActiveTrip(trip: any,index: number) {
    this.currentTrip = trip;
    this.currentIndex = index;
  }


}

解决方法

也许您必须在后端启用 CORS（我猜是浏览器控制台末尾的“未知错误”，这就是您的 console.log(error)）。

您可以尝试使用这个 chrome 扩展来测试：https://chrome.google.com/webstore/detail/allow-cors-access-control/lhobafahddgcelffkeicbaginigeejlf?hl=en。

如果您的后端响应显示启用了扩展程序，则您必须启用 CORS：

https://docs.microsoft.com/en-us/aspnet/core/security/cors?view=aspnetcore-3.1#ecors