我正在尝试从服务内部而不是从组件进行数据库插入，无论我做什么，都会给我带来空对象错误。我也用
DbContextDbContextFactoryConsoleWebhookReceiver和
DbContextDbContextFactory：
Program.cs
using BlazorApp.Services;
using BotTrading.Controllers;
using BotTrading.Data;
using BotTrading.Services;
using Microsoft.EntityFrameworkCore;
var builder = WebApplication.CreateBuilder(args);
// Add services to the container.
builder.Services.AddRazorPages();
builder.Services.AddServerSideBlazor();
builder.Services.AddSingleton<WeatherForecastService>();
builder.Services.AddScoped<IReceiveWebhook, ConsoleWebhookReceiver>();
builder.Services.AddScoped<IWebhookService, WebhookService>();
builder.Services.AddScoped<WebhookService>();
builder.Services.AddControllers();
builder.Services.AddDbContextFactory<AppDBContext>(options =>
options
.EnableSensitiveDataLogging()
.UseSqlite(builder.Configuration.GetConnectionString("Database")));
var app = builder.Build();
var webhookService = app.Services.GetRequiredService<WebhookService>();
// var cryptoService = app.Services.GetRequiredService<CryptoService>();
// Configure the HTTP request pipeline.
if (!app.Environment.IsDevelopment())
{
app.UseExceptionHandler("/Error");
app.UseHsts();
}
app.UseHttpsRedirection();
app.UseStaticFiles();
app.MapControllers();
// app.UseMvc();
app.UseRouting();
app.MapBlazorHub();
app.MapFallbackToPage("/_Host");
//Listen for POST webhooks
app.MapPost("/webhooks", async (HttpContext context, IReceiveWebhook receiveWebook) =>
{
using StreamReader stream = new StreamReader(context.Request.Body);
return await receiveWebook.ProcessRequest(await stream.ReadToEndAsync());
});
app.Run();
：
ConsoleWebhookReceiver.cs
public class ConsoleWebhookReceiver : IReceiveWebhook
{
private readonly AppDBContext _appDbContext;
private readonly IDbContextFactory<AppDBContext> _contextFactory;
/// <summary>
/// Writes the POST request body to the console and returns JSON and then inserts into database
/// </summary>
public async Task<string> ProcessRequest(string requestBody)
{
var context = await _contextFactory.CreateDbContextAsync();
WebhookService webhookService = new WebhookService(context);
// This is where you would put your actual business logic for receiving webhooks
Console.WriteLine($"Request Body: {requestBody}");
Webhook item = JsonConvert.DeserializeObject<Webhook>(requestBody);
// These two calls to WebhookReceiver is where I am getting
// the null object reference. The item is passed into my
// webhookService, the item is not null, but in the service
// there is no context
webhookService.CreateWebhook(item);
Webhook webhook = webhookService.GetWebhookById(1).Result;
return "{\"message\" : \"Thanks! We got your webhook\"}";
}
}
：
IReceiveWebhook.cs
namespace BlazorApp.Services
{
public interface IReceiveWebhook
{
Task<string> ProcessRequest(string requestBody);
}
}
：
WebhookService.cs
using System;
using System.Threading.Tasks;
using BotTrading.Data;
using BotTrading.Services;
using Flurl.Util;
using Microsoft.EntityFrameworkCore;
using Newtonsoft.Json;
using NgrokApi;
namespace BlazorApp.Services
{
public class WebhookService : IWebhookService
{
private readonly IDbContextFactory<AppDBContext> _contextFactory;
private readonly AppDBContext _context;
// public WebhookService(IDbContextFactory<AppDBContext> contextFactory)
// {
// _contextFactory = contextFactory;
// }
public WebhookService(AppDBContext context)
{
_context = context;
}
public async Task<List<Webhook>> GetWebhookList()
{
using (var context = await _contextFactory.CreateDbContextAsync())
{
return await context.Webhooks
.ToListAsync();
}
}
public async Task<Webhook> GetWebhookById(int id)
{
using (var context = await _contextFactory.CreateDbContextAsync())
{
return await context.Webhooks
.FirstOrDefaultAsync(x => x.Id == id);
}
}
public async Task<Webhook> CreateWebhook(Webhook webhook)
{
using (var context = await _contextFactory.CreateDbContextAsync())
{
Console.WriteLine("webhook: " + webhook.Base);
context.Webhooks.AddAsync(webhook);
await context.SaveChangesAsync();
return webhook;
}
}
public async Task UpdateWebhook(Webhook player)
{
using (var context = _contextFactory.CreateDbContext())
{
context.Webhooks.Update(player);
await context.SaveChangesAsync();
}
}
public async Task DeleteWebhook(Webhook player)
{
using (var context = _contextFactory.CreateDbContext())
{
context.Webhooks.Remove(player);
await context.SaveChangesAsync();
}
}
}
}
：
IWebhookService.cs
AppDBContext.cs
using BotTrading.Data;
namespace BotTrading.Services;
public interface IWebhookService
{
Task<List<Webhook>> GetWebhookList();
Task<Webhook> GetWebhookById(int id);
Task<Webhook> CreateWebhook(Webhook webhook);
Task UpdateWebhook(Webhook webhook);
Task DeleteWebhook(Webhook webhook);
}
这是例外情况
失败：Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware[1]
执行请求时发生未处理的异常。
System.NullReferenceException：未将对象引用设置为对象的实例。
在 BotTrading.Controllers.ConsoleWebhookReceiver.ProcessRequest（字符串 requestBody）
在程序中。<>c.b__0_2>d.MoveNext()
--- 先前位置的堆栈跟踪结束 ---<<$> 在 Microsoft.AspNetCore.Http.RequestDelegateFactory.g__ExecuteAwaited|134_0（任务`1 任务，HttpContext httpContext）
在 Microsoft.AspNetCore.Authorization.AuthorizationMiddleware.Invoke（HttpContext 上下文）
在 Microsoft.AspNetCore.Authentication.AuthenticationMiddleware.Invoke（HttpContext 上下文）
在 Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddlewareImpl.Invoke（HttpContext 上下文）
它只是缺少一个
using Microsoft.EntityFrameworkCore;
namespace BotTrading.Data;
public class AppDBContext : DbContext
{
protected readonly IConfiguration Configuration;
public AppDBContext(DbContextOptions<AppDBContext> options)
: base(options)
{
}
protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
{
optionsBuilder
.EnableSensitiveDataLogging()
.EnableDetailedErrors()
.LogTo(Console.WriteLine, new[] { DbLoggerCategory.Infrastructure.Name })
.UseSqlite(Configuration.GetConnectionString("Database"));
}
public DbSet<Crypto> Cryptos { get; set; }
public DbSet<Trade> Trades { get; set; }
public DbSet<Webhook> Webhooks { get; set; }
}
然后它也应该被注入或解析到某个地方。