ProviderIncompatibleException在运行时第一次。但是，不是在第二次 [英] ProviderIncompatibleException when running first time. But, not in second time

问题描述

因此，基本上我在项目中使用 EF 与反向POCO代码第一代生成器。

我的连接字符串看起来像这样：

 < connectionStrings> 
< add name =HistoryDBContextconnectionString =providerName =System.Data.SqlClient/> 
< add name =ProjectMgtContextconnectionString =data source = xxx; initial catalog = xxx; user id = xx; password = xxx; MultipleActiveResultSets = True; App = EntityFrameworkproviderName =System.Data.SqlClient /> 
< / connectionStrings> 
  

这个想法是我要阅读 connectionString for HistoryDBContext from ProjectMgtContext （这是正常工作），然后重写 connectionString使用

  public static void WriteConnectionString（string connectionString）
 {
 var config = ConfigurationManager.OpenExeConfiguration（ConfigurationUserLevel.None）; 
 
 var connectionStringsSection =（ConnectionStringsSection）config.GetSection（connectionStrings）; 
 
 connectionStringsSection.ConnectionStrings [HistoryDBContext]。ConnectionString = connectionString; 
 
 config.Save（）; 
 
 ConfigurationManager.RefreshSection（connectionStrings）; 
} 
  

但是，这仅适用于 code>我运行我的项目，因为在第一次运行时，它抱怨说 connectionString 是空的：

所以，显然我的方法不起作用。我应该如何处理？

谢谢

修改

更多代码：

  while（ProjectManager.HaveProjects（））
 {
 var project = ProjectManager.GetNextProject（）; 
 
 if（project == null）continue; 
 
 / *将当前项目写入配置文件* / 
 Connection.WriteConnectionString（project.ConnectionString）; 
 ... 
} 
  

解决方案

  public partial class ProjectMgtContext：DbContext {
 public静态字符串DefaultConnectionString; 
 public TestEntities（）
：base（DefaultConnectionString）
 {
} 
  

然后更新DefaultConnectionString静态属性。如果您从模板生成上下文 - 编辑模板以添加如上所述的默认连接字符串。

So, basically I'm using EF with Reverse POCO Code First Generator in my project.

My connection Strings look like this:

<connectionStrings>
    <add name="HistoryDBContext" connectionString="" providerName="System.Data.SqlClient" />
    <add name="ProjectMgtContext" connectionString="data source=xxx;initial catalog=xxx;user id=xx;password=xxx;MultipleActiveResultSets=True;App=EntityFramework" providerName="System.Data.SqlClient" />
</connectionStrings>

The idea is that I am going to read the connectionString for HistoryDBContext from ProjectMgtContext (which is working fine) and then rewrite the connectionString from HistoryDBContext using:

public static void WriteConnectionString(string connectionString)
{
    var config = ConfigurationManager.OpenExeConfiguration(ConfigurationUserLevel.None);

    var connectionStringsSection = (ConnectionStringsSection) config.GetSection("connectionStrings");

    connectionStringsSection.ConnectionStrings["HistoryDBContext"].ConnectionString = connectionString;

    config.Save();

    ConfigurationManager.RefreshSection("connectionStrings");
}

However, this only works the second time that I run my project because during the first run, it complains that the connectionString is empty:

So, obviously my approach is not working. How should I approach this?

Thank you

Edit

More code:

while (ProjectManager.HaveProjects())
{
    var project = ProjectManager.GetNextProject();

    if (project == null) continue;

    /*Write the current project to the configuration file*/
    Connection.WriteConnectionString(project.ConnectionString);
    ...
}

解决方案

Well most likely it won't work this way. EF might not re-read your connection string from configuration every time it needs it. It might as well cache either whole configuration or just connection string in memory. App.config is for connection strings that are not changing often during application runtime (or better at all). Just pass connection string to your ProjectMgtContext directly, or do like this:

public partial class ProjectMgtContext : DbContext {
    public static string DefaultConnectionString;
    public TestEntities()
        : base(DefaultConnectionString)
    {
 }

And then update DefaultConnectionString static property. If you generate your context from template - edit template to add default connection string as above.

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