How can I add database connection string to Azure Functions

Question

Can someone let me know how I can add or access an app.config file to Azure functions to add a database connection string? If you're not supposed to add an app.config and there is a better way to access an external database to execute the function please let me know best practices. Thanks!

Answer 1

1. most important thing is that we understand local.settings.json file IS NOT FOR AZURE. it is to run your app in the local as the name is clearly saying. So solution is nothing to do with this file.

2. App.Config or Web.Config doesnt work for Azure function connection strings. If you have Database Layer Library you cant overwrite connection string using any of these as you would do in Asp.Net applications.

3. In order to work with, you need to define your connection string on the azure portal under the  Application Settings  in your Azure function. There is Connection strings. there you should copy your connection string of your DBContext. if it is edmx, it will look like as below. There is Connection type, I use it SQlAzure but I tested with Custom(somebody claimed only works with custom) works with both.

    metadata=res:///Models.myDB.csdl|res:///Models.myDB.ssdl|res://*/Models.myDB.msl;provider=System.Data.SqlClient;provider connection string='data source=[yourdbURL];initial catalog=myDB;persist security info=True;user id=xxxx;password=xxx;MultipleActiveResultSets=True;App=EntityFramework

4. After you set this up, You need to read the url in your application and provide the DBContext. DbContext implements a constructor with connection string parameter. By default constructor is without any parameter but you can extend this. if you are using POCO classes, you can amend the DbContext class simply. If you use Database generated Edmx classes like I do, you don't want to touch the auto generated edmx classes, instead you want to create partial class in the same namespace and extend this class as below.

   This is auto generated DbContext

   namespace myApp.Data.Models
   {   
   
       public partial class myDBEntities : DbContext
       {
           public myDBEntities()
              : base("name=myDBEntities")
           {
           }
   
           protected override void OnModelCreating(DbModelBuilder modelBuilder)
           {
               throw new UnintentionalCodeFirstException();
           }
   
   }

   This is auto generated DbContext

   namespace myApp.Data.Models
   {   
   
       public partial class myDBEntities : DbContext
       {
           public myDBEntities()
              : base("name=myDBEntities")
           {
           }
   
           protected override void OnModelCreating(DbModelBuilder modelBuilder)
           {
               throw new UnintentionalCodeFirstException();
           }
   
   }

5. After all you can get the connection string from azure settings, in your Azure Function project with the code below and provide to your DbContext myDBEntities is the name you gave in the azure portal for your connection string.

var connString = ConfigurationManager.ConnectionStrings["myDBEntities"].ConnectionString;


 using (var dbContext = new myDBEntities(connString))
{
        //TODO:
}

Hope this helps!!

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Thank you!!

Answer 2

The best way to do this is to add a Connection String from the Azure portal:

• From your Function App UI, click Function App Settings
• Settings / Application Settings
• Add connection strings

They will then be available using the same logic as if they were in a web.config, e.g.

var conn = System.Configuration.ConfigurationManager
                 .ConnectionStrings["MyConn"].ConnectionString;

Or if you're using a non-.NET language, you can use App Settings instead, which become simple environment variables at runtime that your functions can access.

Comments

Hi, this is exactly what I'm trying to find. In a non-.NET language, specifically Python, what name does the variable take at runtime? I assume it is something like a dict in python from where you can access a connection string as varName['ConnectionStrings'][0] maybe?

---

Yes,

You can use a dictionary to accomplish that, you can create them on the fly to assign to the 'dict'. Try to avoid global variables and local variables. Instead of this, create your own 'dict' and assign.