添加的ConnectionString中的app.config [英] Add connectionstring in app.config

问题描述

我在C＃类库已经有几个班和一个app.config中。我已经把在ConnectionString中的app.config如下：

I have a class library in C# has has several classes and a app.config. I have put ConnectionString in app.config as follows:

<connectionStrings>
    <add name="TRN_DB"
         connectionString="Database=TRN;Server=NDTSSN;User ID=ln_users2;Password=%4nu$r!;Connection Timeout=30;pooling=false;" 
         providerName="System.Data.SqlClient"
    />
</connectionStrings>

我尝试在我的项目中的一个类打开连接字符串如下：

I try to open connection string in one of the classes in my project as follows:

     string connectionString = ConfigurationManager.ConnectionStrings["TRN_DB"].ConnectionString.ToString();
       SqlConnection con = new SqlConnection(connectionString);
       con.Open();

但它给了我一个错误：

But it gave me an error as:

{未将对象引用设置到对象的实例。}

{"Object reference not set to an instance of an object."}

连接字符串是正确的，当我在Web项目中使用同样的方法在web.config内，是否有人知道如何如何，我可以在app.config中访问它？我已经使用这种方式太：

The connection string is correct when I use same way in web project inside the web.config, Does anybody know how how I can access it in app.config? I already use it this way too:

 string connectionString = System.Configuration.ConfigurationSettings.AppSettings["TRN_DB"];

这人给我这个错误：

这方法已过时，它已取代System.Configuration！System.Configuration.ConfigurationManager.Appsettings

This method is obsolete, it has been replaced by System.Configuration!System.Configuration.ConfigurationManager.Appsettings

要清楚，我没有在我的解决方案的其他项目，我希望我的类库独立工作。我不能够应用的web项目，并web.config中说。所以，我不是要补充连接字符串的app.config和访问它，或者一个web.config添加到我的类库项目。那我不知道哪一个是可行的。

To make it clear, I don't have any other project in my solution, as I want my class library to work independently. I am not able to app web project and web.config to that. So I either should add connection string to app.config and access it Or add a web.config to my class library project. That I am not sure which one is doable.

推荐答案

如果您运行的是网络与类项目图书馆，
连接字符串添加到的web.config 在网站项目

If you are running Web project with Class library, add connection string to web.config inside the Web project

如果您正在运行的控制台/ WinForm的与类库，
连接字符串添加到的app.config 里面的项目在控制台/ WinForm的项目

If you are running Console/WinForm project with Class library, add connection string to app.config inside the Console/WinForm project

修改的库项目不会工作你的情况配置。

modifying config in Library project will not work in your case.

这篇关于添加的ConnectionString中的app.config的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！