C# compose connectionString in app.config using appSettings parameters

Question

Is it possible to compose some xml entry in app.config (in my case some of connectionStrings) using appSettings parameters from the same file? Example:

  <connectionStrings>
    <add name="MyContextDB" connectionString="Data Source =.;Initial Catalog = EFMyContextDB;Integrated Security = false;User Id=user;Password=pwd" providerName="System.Data.SqlClient" />
  </connectionStrings>

  <appSettings>
    <add key="UserId" value="userValue" />
    <add key="Password" value="pwdValue" />
  </appSettings>

I want to somehow use UserId instead of user and Password instead of pwd values of MyContextDB's connectionString.

This connection is then used in DbContext object:

public class MyContext : DbContext
{
    public MyContext() : base("name = MyContextDB") { }
    ...
}

Daniel A. White · Accepted Answer · 2016-08-30 14:22:41Z

2

You certainly can look at using SqlConnectionStringBuilder. Pass your existing connection string in to the constructor. Set the Password and the UserID properties. Then call ToString().

You won't be able to pass the connection string like that for your DbContext. You could consider refactoring that to a factory pattern or something similar.

I would also consider using config transforms to actually update the config files at build time.

edited Aug 30, 2016 at 14:22

answered Aug 30, 2016 at 14:15

Daniel A. White

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Gustavo F · Accepted Answer · 2016-08-30 14:22:04Z

0

Use the SqlConnectionStringBuilder:

    System.Data.SqlClient.SqlConnectionStringBuilder builder = new System.Data.SqlClient.SqlConnectionStringBuilder(System.Configuration.ConfigurationManager.ConnectionStrings["MyContextDB"].ToString());

    builder.UserID = System.Configuration.ConfigurationManager.AppSettings["UserId"];
    builder.Password = System.Configuration.ConfigurationManager.AppSettings["Password"];

Then, to get the new connectionstring:

builder.ToString();

answered Aug 30, 2016 at 14:22

Gustavo F

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2 Comments

Daniel A. White Over a year ago

isn't this what i said?

Gustavo F Over a year ago

Sorry, I did not see your comment.

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