使用带有DI的多数据库实例的nHibernate [英] using nHibernate with multi DB instances with DI

问题描述

所以我有多个数据库实例和一个Web应用程序。
取决于url名称，我知道我需要与哪个db实例交谈。
我想更改旧的丑陋DAL与nhibernate一起使用，我想用DI来完成。
所以，假设我有这个类：

  class CompanyDal（ISession session）// nhibernate session 
 {
 Save（ICompany company）
 {
 session.Save（company）
} 
} 
  

所以我在创建DAL对象时注入了hibernate会话。但是我的IOC需要知道注入哪个会话，这意味着哪个连接字符串。
如果我只有一个单身工厂，我会为不同的网站（不同的数据库）得到错误的会话。我希望我解释它，以便大家都能理解。
谢谢

解决方案

假设所有数据库都具有相同的模式，您可以使用自定义的DriverConnectionProvider 。在下面的代码中，我将web.config中的连接字符串加载到字典中，然后使用URL中的tenant路由值检索它们。

  public class TenantConnectionProvider：DriverConnectionProvider 
 {
 private IDictionary< string，string> _tenantConnectionStrings; 
 
 public override void Configure（IDictionary< string，string>设置）
 {
 //从配置文件加载连接字符串
 _tenantConnectionStrings = new Dictionary< string，string> ;（StringComparer.OrdinalIgnoreCase）; 
 foreach（ConfigurationManager.ConnectionStrings中的ConnectionStringSettings connectionStringSetting）
 {
 _tenantConnectionStrings.Add（connectionStringSetting.Name，connectionStringSetting.ConnectionString）; 
} 
 
 base.Configure（settings）; 
} 
 
 public override IDbConnection GetConnection（）
 {
 var connectionString = GetConnectionString（）; //未显示，我的Web API为
 var connection = new SqlConnection（connectionString）; 
 connection.Open（）; 
返回连接; 
 
 
  

然后我使用Fluent NHibernate配置它：

  //即使使用自定义提供程序，也必须设置连接字符串
 var config = Fluently.Configure（）
。数据库（MsSqlConfiguration.MsSql2008.ConnectionString（custom）。Provider< TenantConnectionProvider>）
 .Mappings（m => 
 {
 m.FluentMappings.AddFromAssemblyOf< MyClass>（） ; 
}）; 
  

So I have multi db instances and One web application. depending on the url name, I know what db instance I need to talk to. I want to change the old ugly DAL to work with nhibernate and I want to use DI to do that. so, let say I have this class:

class CompanyDal(ISession session) //nhibernate session
{
    Save(ICompany company)
    { 
        session.Save(company)
    }
}

so I am injecting the hibernate session when creating the DAL object. but my IOC needs to know which session to inject, meaning which connection string. If I have only one singleton factory I will get the wrong session for different urls (different db)

I hope I explained it so you all can understand. thank you

解决方案

Assuming all the databases have the same schema, you can dynamically switch the connection using a custom DriverConnectionProvider. In the code below I am loading the connection strings from web.config into a dictionary, then retrieving them using a "tenant" route value from the URL.

public class TenantConnectionProvider : DriverConnectionProvider
{
    private IDictionary<string, string> _tenantConnectionStrings;

    public override void Configure(IDictionary<string, string> settings)
    {
        // Load connection strings from config file
        _tenantConnectionStrings = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase);
        foreach (ConnectionStringSettings connectionStringSetting in ConfigurationManager.ConnectionStrings)
        {
            _tenantConnectionStrings.Add(connectionStringSetting.Name, connectionStringSetting.ConnectionString);
        }

        base.Configure(settings);
    }

    public override IDbConnection GetConnection()
    {
        var connectionString = GetConnectionString(); //not shown, mine is for Web API
        var connection = new SqlConnection(connectionString);
        connection.Open();
        return connection;
    }
}

I then configure this using Fluent NHibernate:

// connection string has to be set even though custom provider is used
var config = Fluently.Configure()
    .Database(MsSqlConfiguration.MsSql2008.ConnectionString("custom").Provider<TenantConnectionProvider>)
    .Mappings(m =>
    {
        m.FluentMappings.AddFromAssemblyOf<MyClass>();
    });

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