[英]Entity Framework(Code First to an existing database) - overwrite a connection string in app.config at runtime
I need to connect my app(windows forms) to a SQL Server Database dynamically and i have in my app.config, 3 connection strings(where 1 of them i want to change dynamically). 我需要将我的应用程序(Windows窗体)动态连接到SQL Server数据库,并且在我的app.config中有3个连接字符串(其中1个我想动态更改)。
Bellow is the app.config: 波纹管是app.config:
<connectionStrings>
<add name="NfceConnPortalInterno"
providerName="System.Data.SqlClient"
connectionString="Data Source=lab;Initial Catalog=portal;Persist Security Info=True;User ID=micportal;Password=150302;language=us_english"/>
<add name="NfceConnPortalExterno"
providerName="System.Data.SqlClient"
connectionString="Data Source=10.10.0.1,8081;Initial Catalog=portal;Persist Security Info=True;User ID=micportal;Password=\\-W?98xpT;language=us_english"/>
<!-- this one will be modified in runtime. -->
<add
name="NfceContext"
connectionString="data source=(localdb)\v11.0;initial catalog=Blogging;Connection Timeout=320;Persist Security Info=True;integrated security=True;language=us_english;MultipleActiveResultSets=True;App=EntityFramework"
providerName="System.Data.SqlClient" />
</connectionStrings>
In my DbContext i have this: 在我的DbContext中,我有这个:
public NfceContext() : base("name=NfceContext")
{
}
Im trying an approach of changing this connectionString in a class, using AppDomain.CurrentDomain.SetupInformation.ConfigurationFile . 我正在尝试使用AppDomain.CurrentDomain.SetupInformation.ConfigurationFile在类中更改此connectionString的方法。 If i check running on debug mode, the connectionStrings on the app.vshost.exe.config is changed, but the app.config not(I guess that the app.config should be modified). 如果我检查在调试模式下运行,则app.vshost.exe.config上的connectionStrings会更改,但app.config不会(我想应该修改app.config)。
When i try to do for an example: context.MyEntity.ToList(), it´s gives me an error like this"you don´t have permission to create table..." and if i check the connection string at this time, it´s the old one(before i modify). 当我尝试举一个例子:context.MyEntity.ToList()时,它给我这样的错误,例如“您无权创建表...”,并且如果我此时检查连接字符串,它是旧的(在我修改之前)。
The code bellow can show what i said: 下面的代码可以显示我所说的内容:
Method to overwrite the connection string in the app.config: 覆盖app.config中的连接字符串的方法:
private void ModifyNfceContext(string dataSource, string portal, string senha)
{
XmlDocument xml = new XmlDocument();
xml.Load(AppDomain.CurrentDomain.SetupInformation.ConfigurationFile);
XmlNodeList lista = xml.DocumentElement.SelectNodes(String.Format("connectionStrings/add [@name='{0}']", "NfceContext"));
XmlNode node = lista[0];
string connectionString = node.Attributes["connectionString"].Value;
SqlConnectionStringBuilder connStringBuilder = new SqlConnectionStringBuilder(connectionString);
connStringBuilder.InitialCatalog = portal;
connStringBuilder.DataSource = dataSource;
connStringBuilder.IntegratedSecurity = true;
connStringBuilder.UserID = "mic" + portal;
connStringBuilder.Password = senha;
node.Attributes["connectionString"].Value = connStringBuilder.ConnectionString;
xml.Save(AppDomain.CurrentDomain.SetupInformation.ConfigurationFile);
}
The controller´s contructor: 控制器的构造器:
public NfceController()
{
if (this.context == null)
{
ModifyNfceContext(this.dataSource, this.portal, this.senha);
//At this moment, the connectionString should be modified.
this.context = new NfceContext();
}
this.repositoryNfce = new RepositoryNfce(context);
}
So, what am i doing wrong? 那么,我在做什么错呢? Do i need to change the app.config instead of vhost.config? 我需要更改app.config而不是vhost.config吗?
I had written this article on setting connection strings at runtime for database first. 我写过这篇文章 ,首先介绍了在运行时为数据库设置连接字符串。 Check it out; 看看这个; it might be useful even in your case. 即使您的情况也可能很有用。
In short, you can create a partial class to get access to a DbContext constructor overload that takes a connection string as a parameter (example from my article): 简而言之,您可以创建一个子类来访问DbContext构造函数重载,该重载将连接字符串作为参数(来自我的文章的示例):
public partial class peopleEntities : DbContext
{
public peopleEntities(String connectionString)
: base(connectionString)
{
}
}
And then you can use EntityConnectionStringBuilder to build and pass the connection string (example also from my article): 然后,您可以使用EntityConnectionStringBuilder生成并传递连接字符串(示例也来自我的文章):
EntityConnectionStringBuilder csb = new EntityConnectionStringBuilder();
csb.Metadata = "res://*/Model1.csdl|res://*/Model1.ssdl|res://*/Model1.msl";
csb.Provider = "System.Data.SqlServerCe.4.0";
csb.ProviderConnectionString = "data source=people.sdf";
String entityConnStr = csb.ToString();
If your NfceContext is not static object, you can create another constructor what will take a connection string name as the parametr, something like this: 如果您的NfceContext不是静态对象,则可以创建另一个构造函数,该构造函数将连接字符串名称作为参数,如下所示:
public class NfceContext : DbContext{
public NfceContext (string appConfigConStrName) : base (appConfigConStrName) { }
}
Otherwise, if your context is static object, what is bad practice as I think, you can write public method what will create new instance of DbContext inside your NfceContext: 否则,如果您的上下文是静态对象,那么我认为这是一种不好的做法,您可以编写公共方法在NfceContext内创建DbContext的新实例的方法:
public class NfceContext : DbContext{
static NfceContext context;
public static NfceContext() {
context = new NfceContext();
}
public void ChangeDB(string appConfigConStr) {
context = new NfceContext(appConfigConStr);
}
}
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