How to get the EF Core Connection String?

Time needed: 10 minutes

How to extract the connectionstring from your Database Context in C#?

1. Include the following using statements

   These work for Microsoft SQL Server connection strings – you might need something else if your data source is different.
   
   using Microsoft.Data.SqlClient;
using Microsoft.EntityFrameworkCore;

2. Instantiate your DbContext (or inject it)

   Whatever you do, just have it set – this is the variable we’ll be using later on as well:
   
   // Injected in the constructor of the controller
// or instantiated in the code
ApplicationDbContext db;
3. Get the connection and access ConnectionString property

   Like shown below:
   
   // Fetch the DbConnection object and
// grab its Connection String
db.Database.GetDbConnection().ConnectionString
   
   Oh – a quick word of advice:
   The connection string might contain your password. As Zaki Bhai points out in the comments below, this happens only if Persist Security Info = True has been specified in the connection string.
   
   Most of the time, you don’t want to do this – and definitely do not log the connection string anywhere as is. If you plan to push it to Application Insights or something, remove the password from the string before doing that. Below I’ll show one example on how to do that!

4. (Optional) Sanitize your connection string to remove the password 😅

   In case you’re displaying or logging this information somewhere, you need to (at the very least) remove or replace the password.
   
   This sample would be one way to achieve just that:
   
   Regex r = new Regex("Password='.+'");
string dummyPassword = "Password='Password123'";
string cs = db.Database.GetDbConnection().ConnectionString;
string csSanitized= r.Replace(cs, dummyPassword);
_monitor.TrackEventDebug("ReadOnlyDbContext", "ConnectionString", csSanitized);
   
   Now your connection string will be logged with a (hopefully) obvious dummy password. :)