How to pass connection string from web.config to data access project?


I created a data access project, which access database and holds a number of strong typed dataset. When I created dataset in this project, it created a settings.setting file, which reads connection string from app.config file of this project.

However, I created another web project. this project is supposed to consume the data retrieved from data access project. this web project is having connection string in web.config.

my question is how to pass the connection string in web.config from web project to data access project. there is no reason to save the same connection string in different places. keeping connection string in web.config is no doubt easier to modify in deployment.

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nmarunConnect With a Mentor Commented:
To test the theory that your data access project does actually accesses the web.config located in the web application, I did this.

Create a  ASP.NET web application
Create a Class Library (to mock the data access project)
Added the reference System.Configuration to the Class Library project
Added the Class Library project as a reference to the web application.

Added a static method to the Class1 of the Class Lib:

public static string GetCacheString()
    return ConfigurationManager.AppSettings["OutputCachePath"];

I call this in my default.aspx.cs page's page_load method:

public partial class _Default : Page
    protected void Page_Load(object sender, EventArgs e)
        string OutputCachePath = Class1.GetCacheString();

I do see that the value actually came from the web.config file (as there's no app.config file in the class lib project).

nipunuConnect With a Mentor Commented:
You can directly access the web.config connection string like following


            <add name="TestConnection1" connectionString="User ID=abc;Password=1234;Initial Catalog=databasename;Data Source=machinename"/>            

Accessing it from anywhere in the project

SqlConnection dataSourceConnection = new SqlConnection(ConfigurationManager.ConnectionStrings["TestConnection1"].ConnectionString);
viola123Author Commented:
hi, nipunu:

thanks, i am aware I can access the connection string of web.config within this web project.

My question is: How to make my data access project use the connection string in web.config of web project.

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In fact, even if the app.config exists in the class library, ConfigurationManager.AppSettings actually accesses the web.config file only.

viola123Author Commented:
hi, nmarun:

thanks, i think we are getting close. Yes, you demonstrated we can access web.config connection string from data access project.

However, my data access project is holding all strong typed datasets, these datasets are based on the connection in settings.setting, which comes from the app.config of data access project.

How should we use that web.config connection string to update the connection in settings.setting file, rather than read it from app.config?

Whenever you create a new dataset , don't let visual studio make new connction string but choose the one u want and have created in web.config file. check the first link from the above set
viola123Author Commented:
Hi, nipunu:

I read all the links in your last comment but did not work out a way for my situation.

what I need is: get the connection string from web.config and use it in data access project for my datasets.

in those links, the first link actually tries to duplicate the web.config connection string in data access project, rather than use web.config connection string in DAL. the second link did not end up with a final answer. other links are not quite related to my problem.

I want to keep using my current strong typed datasets in DAL and need the web.config connection string to tell those datasets where to read data. yes, I understand we can get the web.config connection string in DAL project, but since those datasets are auto-generated, i have nowhere to add any code to specify which connection string i want to use.

viola123Author Commented:

sorry about the late response. yes, I finally manage to resolve this issue by changing the .desinger.cs file of each strong typle dataset. in that file, I can assign connection string from a self-implemented method.

Thanks for all of you and I will split the point for all involved experts.
viola123Author Commented:
i finally figured out the solution in my way but comments above did help
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