如何在运行时更改 dbcontext 连接字符串中的数据库名称

Question

我的 Asp.Net MVC 应用程序设置如下。 解决方案中有 4 个项目。

• ge.Web
• ge.BLL
• ge.Core
• ge.Entities

控制器在 ge.Web 中初始化 ge.Core 中的存储库对象

 public class MapsController : Controller
 {
      private AssessmentRepository repAssessments = new AssessmentRepository("name=GEContext", schoolCode);

      public ActionResult DisplaySearchResults()
      {
        .....
      }
  }

评估存储库

  public class AssessmentRepository : Repository<Assessment>, IAssessmentRepository
{
    public AssessmentRepository(string connString, string schoolCode)
        :base(connString, schoolCode)
    { }
 }

存储库

  public class Repository<TEntity> : IRepository<TEntity> where TEntity:class
{
    protected readonly GEContext context;


    public Repository(string connString, string schoolCode) {
        context = new GEContext(connString);
    }
 }

GEContext

 public class GEContext : DbContext
 {
    public GEContext(string connString):base(connString) 
    {
        this.Configuration.LazyLoadingEnabled = false;
        Database.SetInitializer(new MySqlInitializer());
    }
  }

DbContext

public class DbContext : IDisposable, IObjectContextAdapter
{
    public DbContext(string nameOrConnectionString);
}

Web.Config

 <add name="GEContext" connectionString="server=localhost;port=4040;uid=root;pwd=xxx;database=ge" providerName="MySql.Data.MySqlClient" />

现在我想用 database=ge_[schoolCode] 替换 web.config 中的“database=ge”。在运行时我该怎么做？

更新 我的解决方案不起作用。所以我再次说明问题。

Web.Config

我已将我的配置文件更改为以下内容（以前 GEContext 是唯一的连接字符串）

<connectionStrings>
<add name="GEContext_sc001" connectionString="server=localhost;port=4040;uid=root;pwd=blabla;database=db_sc001" providerName="MySql.Data.MySqlClient" />
<add name="GEContext_sc002" connectionString="server=localhost;port=4040;uid=root;pwd=blabla;database=db" providerName="MySql.Data.MySqlClient" />

<appSettings>
     <add key="SchoolCodes" value="sc001,sc002"/>

这些是允许的学校代码

现在，当用户在登录屏幕输入学校代码时，系统会根据 SchoolCodes 键中的代码对其进行验证。如果是，那么它应该尝试连接到该特定连接的 connectionString。现在当我的代码来了

UserManager.FindAsync

在 AccountController 的登录功能中，它试图找到 GEContext 时崩溃。那个套装在哪里？我该如何改变它？

我已将控制器中的存储库调用更改如下

private static string schoolCode = (string)System.Web.HttpContext.Current.Session["SchoolCode"];

    private AssessmentRepository repAssessments = new AssessmentRepository("name=GEContext_" + schoolCode);

UPDATE-2 以下出现在 ge.Web

IdentityConfig.cs

  public class ApplicationUserManager : UserManager<ApplicationUser, int>
{
    public ApplicationUserManager(IUserStore<ApplicationUser, int> store)
        : base(store)
    {
    }

     public static ApplicationUserManager Create(IdentityFactoryOptions<ApplicationUserManager> options, IOwinContext context) 
    {
        var manager = new ApplicationUserManager(new UserStore<ApplicationUser, Role, int, UserLogin, UserRole, UserClaim>(context.Get<ApplicationDbContext>()));
  ...........
 }

ge.Core 中存在以下内容

ApplicationDbContext

 public class ApplicationDbContext : IdentityDbContext<ApplicationUser, Role, int, UserLogin, UserRole, UserClaim>
{

     public ApplicationDbContext(string connString)
        : base(connString)
    {
        Database.SetInitializer(new MySqlInitializer());
    }

    public static ApplicationDbContext Create()
    {

        return new ApplicationDbContext("name=GEContext_");
    }
}

我如何将 schoolCode 从 ge.web 传递到 ge.Core（答案应该是直截了当的，但目前我无法理解）

UPDATE-3

正如 itikhomi 所说并得到 this post 的帮助，我已将代码更改如下

1. 在 ApplicationDbContext 类中添加了以下内容

   公共静态 ApplicationDbContext 创建（字符串 scCode）{ return new ApplicationDbContext("name=GEContext_" + scCode); }

2. 在 AccountController 中登录

   var appDbContext = ApplicationDbContext.Create(model.SchoolCode);

               Request.GetOwinContext().Set<ApplicationDbContext>(appDbContext);
   

它仍然没有找到正确的数据库

Answer 1

你有两种方法

1)

    using System.Data.SqlClient;

         public class Repository<TEntity> : IRepository<TEntity> where TEntity:class
        {
            protected readonly GEContext context;


            public Repository(string connString, string schoolCode) {
                context = new GEContext(connString);
                var connection = new SqlConnectionStringBuilder(context.Database.Connection.ConnectionString);
                connection.InitialCatalog = "YOUR_PREFIX_FROMSOMEWHERE"+schoolCode;
                context.Database.Connection.ConnectionString = connection.ConnectionString;
            }
         }

2）如果您想在使用前打开连接时切换ChangeDatabase：

//open connection if it close
    context.Database.Connection.ChangeDatabase("DATABASE-NAME");

注意：如果使用 ChangeDatabase 连接应该已经打开

更新3：

你需要做一些这样的思考：

 public class ApplicationDbContext : IdentityDbContext<ApplicationUser>
    {
        public ApplicationDbContext()
            : base("DefaultConnection", throwIfV1Schema: false)
        {

        }

        public ApplicationDbContext(string schoolCode)
            : base(schoolCode)
        {
            var connection = new SqlConnectionStringBuilder(this.Database.Connection.ConnectionString);
            connection.InitialCatalog = "YOUR_PREFIX_FROMSOMEWHERE" + schoolCode;
            this.Database.Connection.ConnectionString = connection.ConnectionString;
        }

        public static ApplicationDbContext Create()
        {
            return new ApplicationDbContext();
        }
    }

在帐户控制器中：

public ApplicationSignInManager SignInManager
        {
            get
            {

                if (_signInManager == null)
                {
                    var code = HttpContext.Request.Form.Get("SchoolCode");//Get from FORM\QueryString\Session whatever you wants
                    if (code != null)
                    {
                        HttpContext.GetOwinContext().Set<ApplicationSignInManager>(new ApplicationSignInManager(_userManager, HttpContext.GetOwinContext().Authentication));
                    }
                    _signInManager = HttpContext.GetOwinContext().Get<ApplicationSignInManager>();
                }

                return _signInManager;
            }
            private set
            {
                _signInManager = value;
            }
        }

 public ApplicationUserManager UserManager
        {
            get
            {
                if (_userManager == null)
                {
                    var code = HttpContext.Request.Form.Get("SchoolCode");//Get from FORM\QueryString\Session whatever you wants
                    if (code != null)
                    {
                        var appDbContext = new ApplicationDbContext(code);

                        HttpContext.GetOwinContext().Set<ApplicationDbContext>(appDbContext);
                        HttpContext.GetOwinContext().Set<ApplicationUserManager>(new ApplicationUserManager(new UserStore<ApplicationUser>(appDbContext))); //OR USE your specified create Method
                    }
                    _userManager = HttpContext.GetOwinContext().GetUserManager<ApplicationUserManager>();
                }
                return _userManager;
            }
            private set
            {
                _userManager = value;
            }
        }

您的问题是在您更改 OWIN 上下文之前创建了 UserManager 的 Store，在这种情况下，最好使用像 here 这样的 DI

Answer 2

您可以为打开的连接更改数据库

context.Database.GetDbConnection().ChangeDatabase("");

Answer 3

我在 itikhomi 的帮助下解决了这个问题..发布最终代码..

ApplicationDbContext

public static ApplicationDbContext Create()
    {
        return new ApplicationDbContext("name=GEContext");
    }

帐户控制器

 public ApplicationUserManager UserManager {
        get
        {
            if (System.Web.HttpContext.Current.Session["SchoolCode"] == null)
                return _userManager ?? HttpContext.GetOwinContext().GetUserManager<ApplicationUserManager>();
            else
            {
                var appDbContext = ApplicationDbContext.Create(System.Web.HttpContext.Current.Session["SchoolCode"].ToString());//new ApplicationDbContext("name=GEContext", System.Web.HttpContext.Current.Session["SchoolCode"].ToString());

                HttpContext.GetOwinContext().Set<ApplicationDbContext>(appDbContext);
                HttpContext.GetOwinContext().Set<ApplicationUserManager>(new ApplicationUserManager(new UserStore<ApplicationUser, Role, int, UserLogin, UserRole, UserClaim>(appDbContext)));

                return HttpContext.GetOwinContext().GetUserManager<ApplicationUserManager>();
            }
        }
        private set
        {
            _userManager = value;
        }
    }