DotNet Minimal API 拒绝连接到 MySql 实例

Question

我已经设置了以下Program.cs：

using Api.Models;
using Microsoft.EntityFrameworkCore;

var builder = WebApplication.CreateBuilder(args);

// Add services to the container.
// Learn more about configuring Swagger/OpenAPI at https://aka.ms/aspnetcore/swashbuckle
builder.Services.AddDbContext<MarketDb>(options =>
{
    var connectionString = builder.Configuration.GetConnectionString("MySqlLocal");
    var serverVersion = new MySqlServerVersion(new Version(8, 3, 0));
    options.UseMySql(connectionString, serverVersion).EnableSensitiveDataLogging().EnableDetailedErrors();
});
builder.Services.AddEndpointsApiExplorer();
builder.Services.AddSwaggerGen();

// build app
var app = builder.Build();

// Configure the HTTP request pipeline.
if (app.Environment.IsDevelopment())
{
    app.UseSwagger();
    app.UseSwaggerUI();
}

app.UseHttpsRedirection();

app.MapGet("/hello", () => "Hello World!");

app.MapGet("/regions", async (MarketDb dbContext) =>
{
    return await dbContext.RegionId.ToListAsync();
}).WithName("GetRegions").WithOpenApi();

app.Run();

连接字符串在appsettings.Development.json中定义：

{
  "Logging": {
    "LogLevel": {
      "Default": "Information",
      "Microsoft.AspNetCore": "Warning"
    }
  },
  "ConnectionStrings": {
    "MySqlLocal": "server=127.0.0.1;port=3306;database=dbservice_test;user=root;password=password"
  }
}

此外，数据库上下文在 MarketDb.cs 中定义：

using Microsoft.EntityFrameworkCore;

namespace Api.Models
{
  public class MarketDb : DbContext
  {
    public MarketDb(DbContextOptions<MarketDb> options) : base(options) { }

    public DbSet<CompletedDates> CompletedDates { get; set; }
    public DbSet<RegionId> RegionId { get; set; }
    public DbSet<TypeId> TypeId { get; set; }
    public DbSet<MarketData> MarketData { get; set; }

    protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
      modelBuilder.Entity<MarketData>()
        .HasOne(m => m.Date)
        .WithMany(d => d.MarketData)
        .HasForeignKey(m => m.DateID);

      modelBuilder.Entity<MarketData>()
        .HasOne(m => m.Region)
        .WithMany(r => r.MarketData)
        .HasForeignKey(m => m.RegionID);

      modelBuilder.Entity<MarketData>()
        .HasOne(m => m.Type)
        .WithMany(t => t.MarketData)
        .HasForeignKey(m => m.TypeID);
    }
  }
}

当我尝试到达

/hello

端点时，我收到“Hello World!”正如预期的那样。

当我尝试到达

/regions

端点时，我收到以下错误：

fail: Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware[1]
      An unhandled exception has occurred while executing the request.
      System.InvalidOperationException: No database provider has been configured for this DbContext. A provider can be configured by overriding the 'DbContext.OnConfiguring' method or by using 'AddDbContext' on the application service provider. If 'AddDbContext' is used, then also ensure that your DbContext type accepts a DbContextOptions<TContext> object in its constructor and passes it to the base constructor for DbContext.

据我所知，我已严格遵循该错误消息的建议，但它仍然绝对无法连接到我在 Docker 容器中运行的 MySql 实例。我可以通过adminer容器访问数据库，也可以使用mysql浏览器访问数据库。我不明白这里有什么问题？

以下是我的模型文件，以防有用：

using System.ComponentModel.DataAnnotations.Schema;
using Microsoft.EntityFrameworkCore;

namespace Api.Models
{
  [Table("type_id")]
  public class TypeId : DbContext
  {
    public int Id { get; set; }
    public string Value { get; set; }
    public ICollection<MarketData> MarketData { get; set; } = new List<MarketData>();

    public TypeId(int id, string value)
    {
      Id = id;
      Value = value ?? throw new ArgumentNullException(nameof(value));
    }
  }
}

using System.ComponentModel.DataAnnotations.Schema;
using Microsoft.EntityFrameworkCore;

namespace Api.Models
{
  [Table("region_id")]
  public class RegionId : DbContext
  {
    public int Id { get; set; }
    public string Value { get; set; }
    public ICollection<MarketData> MarketData { get; set; } = new List<MarketData>();

    public RegionId(int id, string value)
    {
      Id = id;
      Value = value ?? throw new ArgumentNullException(nameof(value));
    }
  }
}

using System.ComponentModel.DataAnnotations.Schema;
using Microsoft.EntityFrameworkCore;


namespace Api.Models
{
  [Table("market_data")]
  [PrimaryKey(nameof(DateID), nameof(RegionID), nameof(TypeID))]
  public class MarketData : DbContext
  {
    public int DateID { get; set; }
    public CompletedDates Date { get; set; }

    public int RegionID { get; set; }
    public RegionId Region { get; set; }
    public int TypeID { get; set; }
    public TypeId Type { get; set; }
    public double Average { get; set; }
    public double Highest { get; set; }
    public double Lowest { get; set; }
    public long Volume { get; set; }
    public long OrderCount { get; set; }

    public MarketData(int dateID, CompletedDates completedDate, int regionID, RegionId region, int typeID, TypeId type, double average, double highest, double lowest, long volume, long orderCount)
    {
      DateID = dateID;
      Date = completedDate ?? throw new ArgumentNullException(nameof(completedDate));
      RegionID = regionID;
      Region = region ?? throw new ArgumentNullException(nameof(region));
      TypeID = typeID;
      Type = type ?? throw new ArgumentNullException(nameof(type));
      Average = average;
      Highest = highest;
      Lowest = lowest;
      Volume = volume;
      OrderCount = orderCount;
    }
  }

}

using Microsoft.EntityFrameworkCore;
using System.ComponentModel.DataAnnotations.Schema;

namespace Api.Models
{
  [Table("completed_dates")]
  public class CompletedDates : DbContext
  {
    public int Id { get; set; }
    public DateOnly Date { get; set; }
    public ICollection<MarketData> MarketData { get; set; } = new List<MarketData>();

  }
}

Answer 1

问题是双重的：

首先：我不应该从

DbContext

继承我的数据模型类：

using System.ComponentModel.DataAnnotations.Schema;
using Microsoft.EntityFrameworkCore;

namespace Api.Models
{
  [Table("type_id")]
---public class TypeId : DbContext
+++public class TypeId
  {
    public int Id { get; set; }
    public string Value { get; set; }
    public ICollection<MarketData> MarketData { get; set; } = new List<MarketData>();

    public TypeId(int id, string value)
    {
      Id = id;
      Value = value ?? throw new ArgumentNullException(nameof(value));
    }
  }
}

...etc.

这暴露了一个警告，我试图消除该警告，即我的 MarketData 模型中的导航属性（TypeId、RegionId 和 CompletedDates）无法提供给构造函数。

相反，它们将成为必需属性，这在实体框架中强制底层 MySql 数据库中的非空关系。这也消除了对显式构造函数的需要：

using System.ComponentModel.DataAnnotations.Schema;
using Microsoft.EntityFrameworkCore;


namespace Api.Models
{
  [Table("market_data")]
  [PrimaryKey(nameof(DateID), nameof(RegionID), nameof(TypeID))]
  public class MarketData
  {
    public int DateID { get; set; }
    public required CompletedDates Date { get; set; }
    public int RegionID { get; set; }
    public required RegionId Region { get; set; }
    public int TypeID { get; set; }
    public required TypeId Type { get; set; }
    public double Average { get; set; }
    public double Highest { get; set; }
    public double Lowest { get; set; }
    public long Volume { get; set; }
    public long OrderCount { get; set; }
  }
}

所以，总而言之，这只是一个愚蠢的错误，我一遍又一遍地读着。