.NET 6 WebApi 错误使用 Visual Studio 2022 当前
Posted
技术标签:
【中文标题】.NET 6 WebApi 错误使用 Visual Studio 2022 当前【英文标题】：.NET 6 WebApi Error using Visual Studio 2022 Current 【发布时间】：2021-12-31 19:46:00 【问题描述】：使用 .NET 6 和 Visual Studio 2022 Current，当我尝试在 Swagger 中测试 API 时出现错误。尝试激活时无法解析服务类型。另外，当我像 builder.Services.AddSingleton
System.AggregateException：'某些服务无法构造（验证服务描述符时出错'ServiceType：WebApi.Utilities.IDataAcess Lifetime：Singleton ImplementationType：WebApi.Utilities.DataAcess'：无法解析类型'的服务' WebApi.Utilities.DBAccess' 同时尝试激活'WebApi.Utilities.DataAcess'。）'
当我运行应用程序时，我得到了如图所示的错误。
我很确定问题出在哪里，但每当我尝试在 .Net 5 或更低版本中添加服务时，它都能正常工作。
控制器
using Microsoft.AspNetCore.Mvc;
using WebApi.Models;
using WebApi.Utilities;
namespace WebApi.Controllers
[ApiController]
[Route("analysis")]
public class analysisDataController : ControllerBase
private IDataAcess _dataAcess;
public analysisDataController(IDataAcess dataAcess)
_dataAcess = dataAcess;
[HttpGet]
public ActionResult<IEnumerable<Clients>> getAllClients()
return _dataAcess.getClients().ToList();
型号
using System.ComponentModel.DataAnnotations;
namespace WebApi.Models
public class Clients
[Required]
public Guid id get; set;
[Required]
public string usercode get; set;
[Required]
public int clientid get; set;
[Required]
public string clientName get; set;
[Required]
public int searchId get; set;
[Required]
public string searchName get; set;
数据访问
using WebApi.Models;
namespace WebApi.Utilities
public class DataAcess : IDataAcess
IDBAccess _dbAccess;
public DataAcess(DBAccess dBAccess)
_dbAccess = dBAccess;
public List<Clients> getClient(string user)
string query = @"SELECT u.UserID AS USER, uc.clientID AS clientID, cl.Name AS clientName,search.ID AS searchID, search.Description AS searchName
FROM testdb1.user_client AS uc
JOIN testdb2.client AS cl ON uc.clientID = cl.ID
JOIN testdb1.user AS u ON u.ID = uc.userID
JOIN testdb2.set ON set.IDClient = uc.clientID
JOIN testdb2.search ON search.IDSet = set.ID
WHERE u.UserID = '" + user + "'";
if (!string.IsNullOrEmpty(user))
var clientData = _dbAccess.RunQuery<Clients>(query);
return clientData.ToList();
else
return null;
public IEnumerable<Clients> getClients()
string query = @"SELECT u.UserID AS USER, uc.clientID AS clientID, cl.Name AS clientName,search.ID AS searchID, search.Description AS searchName
FROM testedb1.user_client AS uc
JOIN testdb1.client AS cl ON uc.clientID = cl.ID
JOIN testdb1.user AS u ON u.ID = uc.userID
JOIN testdb2.set ON set.IDClient = uc.clientID
JOIN testdb2.search ON search.IDSet = set.ID";
var clients = _dbAccess.RunQuery<Clients>(query);
if(clients.Count != 0)
return clients;
return null;
DBAccess 类
using Dapper;
using mysql.Data.MySqlClient;
namespace WebApi.Utilities
public class DBAccess : IDBAccess
ILogger _logger;
public DBAccess(ILogger logger)
_logger = logger;
public List<T> RunQuery<T>(string query)
try
const string conStr = @"server='####';userid='Aubz';password='Test';database='testdb1.clients'";
using (MySqlConnection conn = new MySqlConnection(conStr))
return conn.Query<T>(query).ToList();
catch (Exception e)
_logger.log(e.Message);
throw e;
记录器类
namespace WebApi.Utilities
public class Logger : ILogger
public void log(string logData)
Console.WriteLine(logData);
接口类 IDataAcess
using WebApi.Models;
namespace WebApi.Utilities
public interface IDataAcess
List<Clients> getClient(string user);
IEnumerable<Clients> getClients();
接口 IDBAccess
namespace WebApi.Utilities
public interface IDBAccess
List<T> RunQuery<T>(string query);
界面记录器
namespace WebApi.Utilities
public interface ILogger
void log(string logData);
Program.cs
using WebApi.Utilities;
var builder = WebApplication.CreateBuilder(args);
// Add services to the container.
builder.Services.AddControllers();
// Learn more about configuring Swagger/OpenAPI at https://aka.ms/aspnetcore/swashbuckle
builder.Services.AddEndpointsApiExplorer();
builder.Services.AddSwaggerGen();
var app = builder.Build();
// Configure the HTTP request pipeline.
if (app.Environment.IsDevelopment())
app.UseSwagger();
app.UseSwaggerUI();
app.UseHttpsRedirection();
app.UseAuthorization();
app.MapControllers();
app.Run();
【问题讨论】：
这不是 VS 2022 问题，甚至不是任何 Visual Studio 问题，您根本没有注册该服务。可能类似于builder.Services.AddSingleton<IDataAcess,DataAcess>()。虽然你真的应该看看如何使用依赖注入
我确实添加了 builder.Services.AddSingletonDataAcess，而是DBAccess
【参考方案1】：
问题是你没有配置Dependency injection Container
-
您的控制器依赖于
IDataAcess，但您没有为其提供任何具体实现，请将DataAcess 添加为program.cs 中的Concert 实现
builder.Services.AddSingleton<IDataAcess,DataAcess>();
DataAcess 依赖于具体的DBAccess 并将其存储为IDBAccess，这是毫无意义的，你的类应该依赖于接口而不是具体
IDBAccess _dbAccess;
public DataAcess(IDBAccess dBAccess) //<<< change to be depend on interface IDBAccess
_dbAccess = dBAccess;
-
在program.cs中为
IDBAccess提供具体实现
builder.Services.AddSingleton<IDBAccess ,DBAccess>();
最后，你的 program.cs 会是这个样子
using WebApi.Utilities;
var builder = WebApplication.CreateBuilder(args);
// Add services to the container.
builder.Services.AddSingleton<IDBAccess ,DBAccess>(); //<<<< adding IDBAccess
builder.Services.AddSingleton<IDataAcess,DataAcess>(); //<<<<< adding IDataAcess
builder.Services.AddControllers();
// Learn more about configuring Swagger/OpenAPI at https://aka.ms/aspnetcore/swashbuckle
builder.Services.AddEndpointsApiExplorer();
builder.Services.AddSwaggerGen();
var app = builder.Build();
// Configure the HTTP request pipeline.
if (app.Environment.IsDevelopment())
app.UseSwagger();
app.UseSwaggerUI();
app.UseHttpsRedirection();
app.UseAuthorization();
app.MapControllers();
app.Run();
【讨论】：
感谢您回复我，我确实添加了 builder.Services.AddSingletonIDBAccess ...请阅读答案并确保从步骤 2 ...您是否将 DataAcess 构造函数更改为IDBAccess 不是 DBAccess ?
感谢您回复我。你指的是这部分吗？如果是，请您进一步详细说明。公共数据访问（DBAccess dBAccess）_dbAccess = dBAccess；
是的，我的意思是，你应该把它改成public DataAcess(IDBAccess dBAccess) _dbAccess = dBAccess; ，你应该使用接口IDBAccess而不是具体的DBAccess，并确保将它添加到依赖容器builder.Services.AddSingleton<IDBAccess ,DBAccess>();中程序.cs
谢谢，我知道了，现在可以使用了。以上是关于.NET 6 WebApi 错误使用 Visual Studio 2022 当前的主要内容，如果未能解决你的问题，请参考以下文章
Docker .Net 6 错误程序不包含适用于入口点的静态“主要”方法
.NET6-Asp.Net Core webapi -从零开始的webapi项目
.NET6-Asp.Net Core webapi -从零开始的webapi项目