Unable to create an object of type 'DbContext'. For the different patterns supported at design time

如果在做EFCore migration时碰到如下错误：Unable to create an object of type ‘DbContext’. For the different patterns supported at design time

可尝试以下步骤进行处理：

1：检查是否未实现EFContext默认构造函数
2：尝试清理解决方案，清除目录下的bin和obj
3：如果还不行，尝试在DbContext同级目录下添加类DesignTimeDbContextFactory
也就是自己写点逻辑执行以下执行迁移命令的逻辑

/* This class is needed for EF Core console commands
    * (like Add-Migration and Update-Database commands) */
public class WyJBLandDbContextFactory : IDesignTimeDbContextFactory<WyJBLandDbContext>
{
    public WyJBLandDbContext CreateDbContext(string[] args)
    {
        //BookStoreEfCoreEntityExtensionMappings.Configure();
        var configuration = BuildConfiguration();
        string conn = configuration.GetConnectionString("conn_mysql");
        AddTestLog(conn);
        var builder = new DbContextOptionsBuilder<WyJBLandDbContext>()
            .UseMySql(conn,ServerVersion.AutoDetect(conn));
        return new WyJBLandDbContext(builder.Options);
    }
    /// <summary>
    /// 记录一点内容用于测试
    /// </summary>
    /// <param name="content"></param>
    public void AddTestLog(string content) 
    {
        using (FileStream filestraem = new FileStream("d:/log.txt", FileMode.Append))
        {
            using (StreamWriter write = new StreamWriter(filestraem))
            {
                write.WriteLine(content);
                write.WriteLine("记录时间：" + DateTime.Now.ToString());
                write.WriteLine("----------------------------------------");
                write.Flush();
            }
        }
    }
    private static IConfigurationRoot BuildConfiguration()
    {
        var builder = new ConfigurationBuilder()
            .SetBasePath(Path.Combine(Directory.GetCurrentDirectory(), "../WY.JBLand.API/"))
            .AddJsonFile("appsettings.json", optional: true);
        return builder.Build();
    }
}