启动时数据库迁移

问题描述

我已经阅读了很多关于启动时数据库迁移的文章，无论我使用什么方法，我的努力都无济于事。我遇到的主要问题是 no parameterless constructor defined for type startup

我有我的 DataContext 类

public class DataContext : DbContext
{
    public DataContext(DbContextOptions options) : base(options)
    {
    }

    public DataContext()
    {
    }

    protected override void OnConfiguring(DbContextOptionsBuilder options)
    {
        if (options.IsConfigured)
        {
            //means that context has been added during dependency injection and no further action required.
            
        }
        else
        {
            //means context is being accessed during Add-Migration therefore we need to set the options. The whole DI/Configuration process won't have run yet,so need some other way to get connection string.
            //probably below is a bit too fancy,just hardcoding would be fine.  But anyway it seems to work and transfers to different developers machines
            //you must have {Values: { sqlConnectionString : xyz}} in local.settings.json in Unite.FunctionApp project dir

            var localSettingsJson =
                Path.Combine(local.settings.json");

            var config = new ConfigurationBuilder()
                .AddJsonFile(localSettingsJson,false)
                .Build();

            options.UsesqlServer(config["Values:sqlConnectionString"]);
        }
    }

    protected override void OnModelCreating(ModelBuilder modelBuilder)
    {... }

我的创业班

// register assembly
[assembly: Functionsstartup(typeof(Startup))]

{
// inherit Functionsstartup
public class Startup : Functionsstartup
{
    private DataContext _context;

    public Startup(DataContext context)
    {
        _context = context;
    }

    public override void Configure(IFunctionsHostBuilder builder)
    {

        var executionContextOptions = builder.Services.BuildServiceProvider()
            .GetService<IOptions<ExecutionContextOptions>>().Value;

        var config = new ConfigurationBuilder()
            .SetBasePath(executionContextOptions.AppDirectory)
            .AddJsonFile("local.settings.json",true)
            .AddUserSecrets(Assembly.GetExecutingAssembly(),false)
            .AddEnvironmentvariables()
            .Build();

        builder.Services.AddSingleton<IConfiguration>(config);

        var sqlConnection = config["sqlConnectionString"] ??
                            throw new Exception("sql Connection String Not Defined");

        builder.Services.AddDbContext<DataContext>(options => options.UsesqlServer(sqlConnection));
        _context.Database.MigrateAsync();

    }
}

}

如果我的类中有我的无参数 DataContext 方法，为什么我仍然遇到这个未定义的问题？

解决方法

暂无找到可以解决该程序问题的有效方法，小编努力寻找整理中！

如果你已经找到好的解决方法，欢迎将解决方案带上本链接一起发送给小编。

小编邮箱:dio#foxmail.com (将#修改为@）