使用 Pomelo 实体框架将数据保存到 MySQL答案

【问题标题】：Saving Data to MySQL using Pomelo Entity Framework使用 Pomelo 实体框架将数据保存到 MySQL
【发布时间】：2022-08-06 18:47:35
【问题描述】：

我应用了迁移，可以在 HeidiSQL 中看到表，但在尝试 SaveChanges() 时仍然出现错误

System.InvalidOperationException: \'A relational store has been configured without specifying either the DbConnection or connection string to use.\'

加载指令.cs

using System.ComponentModel.DataAnnotations;

namespace NectarWarehouseAppServer.Models
{
    public class LoadingInstruction
    {
        [Key]
        public int? LoadingInstructionRecordId { get; set; }
        public string RouteId { get; set; }
        public string SalesOrderId { get; set; }       
        public int? LoadersTeamId { get; set; }
    }
}

加载指令上下文.cs

using Microsoft.EntityFrameworkCore;
using System.Diagnostics.CodeAnalysis;
using NectarWarehouseAppServer.Models;

namespace NectarWarehouseAppServer.Models
{
    public class LoadingInstructionContext : DbContext
    {

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

        public LoadingInstructionContext()
        {
        }

        public DbSet<LoadingInstruction> LoadingInstruction { get; set; } = null!;


        protected override void OnModelCreating(ModelBuilder modelBuilder)
        {
             
            //Configuring the one to many relationship

            modelBuilder.Entity<LoadingInstruction>()
                    .HasKey(e => e.LoadingInstructionRecordId);
        }

      
         

        protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
        {
            if (!optionsBuilder.IsConfigured)
            {
                IConfigurationRoot configuration = new ConfigurationBuilder()
                    .SetBasePath(Directory.GetCurrentDirectory())
                    .AddJsonFile(\"appsettings.json\")
                    .Build();
                var connectionString = configuration.GetConnectionString(\"ConnectionString\");
                optionsBuilder.UseMySql(ServerVersion.AutoDetect(connectionString), 
                   optionsBuilder => optionsBuilder.EnableRetryOnFailure(
                    maxRetryCount: 5,
                     maxRetryDelay: System.TimeSpan.FromSeconds(30),
                       errorNumbersToAdd: null));
            }
        }        
    }
}

ILoadingInstructionService.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;

namespace NectarWarehouseAppServer.Models
{
    public interface ILoadingInstructionService
    {
        Task<int> Delete(int id);
        Task<IEnumerable<LoadingInstruction>> FindAll();
        Task<LoadingInstruction> FindOne(int id);
        Task<int> Insert(LoadingInstruction loadingInstruction);
        Task<int> Update(LoadingInstruction loadingInstruction);
      
    }
}

MariaDbContext.cs

using Microsoft.EntityFrameworkCore;
using System.Diagnostics.CodeAnalysis;
using NectarWarehouseAppServer.Models;

namespace NectarWarehouseAppServer.Models
{
    public partial class MariaDbContext : Microsoft.EntityFrameworkCore.DbContext
    {
        public MariaDbContext(DbContextOptions<MariaDbContext> options)
            : base(options)
        {
        }

        public virtual DbSet<Users> Users { get; set; }
        public virtual DbSet<LoadingInstruction> LoadingInstruction { get; set; }

     
    }
}

应用设置.json

{
  \"Logging\": {
    \"LogLevel\": {
      \"Default\": \"Information\",
      \"Microsoft.AspNetCore\": \"Warning\"
    }
  },

  \"ConnectionStrings\": {
    \"ConnectionString\": \"server=localhost;port=3306;database=****;uid=****;pwd=****;\"
  }
}

程序.cs

using Microsoft.EntityFrameworkCore;
using NectarWarehouseAppServer.Models;
using NectarWarehouseAppServer.Services;

var builder = WebApplication.CreateBuilder(args);

// Add services to the container.


builder.Services.AddControllers();
builder.Services.AddDbContextPool<MariaDbContext>(opt =>
{
    opt.UseMySql(builder.Configuration.GetConnectionString(\"ConnectionString\"),
     ServerVersion.AutoDetect(builder.Configuration.GetConnectionString(\"ConnectionString\")),
    builder =>
    {
        builder.EnableRetryOnFailure(5, TimeSpan.FromSeconds(10), null);
    });
});




builder.Services.AddControllers();
builder.Services.AddDbContext<CustomerContext>(opt =>
{
    opt.UseMySql(builder.Configuration.GetConnectionString(\"ConnectionString\"),
     ServerVersion.AutoDetect(builder.Configuration.GetConnectionString(\"ConnectionString\")),
    builder =>
    {
        builder.EnableRetryOnFailure(5, TimeSpan.FromSeconds(10), null);
    });
});

builder.Services.AddScoped<IUsersService, UsersService>();
builder.Services.AddControllers();
builder.Services.AddDbContext<UsersContext>(opt =>
{
    opt.UseMySql(builder.Configuration.GetConnectionString(\"ConnectionString\"),
     ServerVersion.AutoDetect(builder.Configuration.GetConnectionString(\"ConnectionString\")),
    builder =>
    {
        builder.EnableRetryOnFailure(5, TimeSpan.FromSeconds(10), null);
    });
});


builder.Services.AddControllers();
builder.Services.AddDbContext<NectarWarehouseAppServer.Models.RouteContext>(opt =>
{
    opt.UseMySql(builder.Configuration.GetConnectionString(\"ConnectionString\"),
     ServerVersion.AutoDetect(builder.Configuration.GetConnectionString(\"ConnectionString\")),
    builder =>
    {
        builder.EnableRetryOnFailure(5, TimeSpan.FromSeconds(10), null);
    });
});

builder.Services.AddScoped<ILoadingInstructionService, LoadingInstructionService>();
builder.Services.AddControllers();
builder.Services.AddDbContext<LoadingInstructionContext>(opt =>
{
    opt.UseMySql(builder.Configuration.GetConnectionString(\"ConnectionString\"),
     ServerVersion.AutoDetect(builder.Configuration.GetConnectionString(\"ConnectionString\")),
    builder =>
    {
        builder.EnableRetryOnFailure(5, TimeSpan.FromSeconds(10), null);
    });
});

builder.Services.AddConnections();

var app = builder.Build();


// Configure the HTTP request pipeline.
if (app.Environment.IsDevelopment())
{
    app.UseDeveloperExceptionPage();
    //app.UseSwagger();
    //app.UseSwaggerUI(c => c.SwaggerEndpoint(\"/swagger/v1/swagger.json\", \"TodoApi v1\"));
}

app.UseHttpsRedirection();

app.UseAuthorization();

app.MapControllers();

app.Run();

我尝试了几种不同的连接字符串配置，例如使用 \'user\' 而不是 \'uid\' 和 \'password\' 而不是 \'pwd\'，省略端口等。

这是我得到错误的地方

  try
            {
                await using (LoadingInstructionContext dbContext = new LoadingInstructionContext())
                {

                     foreach (var loading in loadingInstructions){
                           LoadingInstruction loadingInstruction = new LoadingInstruction();
                           loadingInstruction.RouteId = \"Route1\";
                           loadingInstruction.SalesOrderId = \"Order1\";
                           loadingInstruction.LoadersTeamId = 0;
                           dbContext.Add(loadingInstruction);
                           dbContext.SaveChanges();
                       }


                    LoadingInstruction loadingInstruction = new LoadingInstruction();
                    dbContext.Add(loadingInstruction);
                    dbContext.SaveChanges();

                }

                return Ok();
            }
            catch (Exception ex)
            {
                Console.WriteLine(ex.ToString());
                return BadRequest(ex.ToString());
            }

标签： c# mysql entity-framework mariadb pomelo-entityframeworkcore-mysql

【解决方案1】：

这是因为您没有发送连接字符串

加载指令上下文.cs：

    protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
    {
        if (!optionsBuilder.IsConfigured)
        {
            IConfigurationRoot configuration = new ConfigurationBuilder()
                .SetBasePath(Directory.GetCurrentDirectory())
                .AddJsonFile("appsettings.json")
                .Build();
            var connectionString = configuration.GetConnectionString("ConnectionString");
            optionsBuilder.UseMySql(connectionString, ServerVersion.AutoDetect(connectionString)); /*send connectionstring with other params*/
        }
    }

【讨论】：

我看到了，不敢相信我错过了！
@Toxic 有美好的一天和编码