Question 405304 in ASP.NET Question posted in
The official documentation can be found here.

Asp.net – Entity Framework Core: use connection string from appsettings.json

I’m trying to use appsettings.json to store the database connection string to use different strings for build configurations. But, I’m getting this exception:

System.InvalidOperationException: A named connection string was used, but the name ‘ConnectionStrings:DefaultConnection’ was not found in the application’s configuration.

Here is my appsettings.json:

"ConnectionStrings": {
    "DefaultConnection": "Server=adserver\VALLOUREC;Database=eddb000;user id=devnepre;Password=nepre;MultipleActiveResultSets=False;TrustServerCertificate=True"
}

And here is how is my database context configuration:

protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
    => optionsBuilder.UseSqlServer("Name=ConnectionStrings:DefaultConnection");

In program.cs, the settings are loaded like this:

builder.Configuration.AddJsonFile("appsettings.json", optional: false, reloadOnChange: true);

And I use AddDbContext but that doesn’t change anything.

I tried some solutions suggested in this topic, but these did not work.

I know I can put the connection string directly in the OnConfiguring function, but I don’t want to do this because every time I scaffold the database, the code is changed and I need to revert this part.

Edit: when i Scaffold the database with this command:

Scaffold-DbContext Name=ConnectionStrings:DefaultConnection Microsoft.EntityFrameworkCore.SqlServer - force

the OnConfiguring is aways replaced by this:

protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
    => optionsBuilder.UseSqlServer("Name=ConnectionStrings:DefaultConnection");

i’m trying to make it works with this implementation to avoid needs to change every time o run the command.

Tags:

3

Answers


  1. Chosen as BEST ANSWER
    0

    Sorry, i took a while to realize that the error was not comming from my main DbContext. The project has a second Database Context that inherit the first one.

    I juest need to add this code:

    builder.Services.AddDbContext<ExampleDbContext>(options =>
options.UseSqlServer(
    builder.Configuration.GetConnectionString("DefaultConnection")));

    for this second and it's work. The inherited DbContext was not able to instance it's parent until i implement the roght constructor receiving the DbContextOptions<>


  2. 0

    as far as I know asp.net uses .net generic host, when I did some research I found that we can get configuration values or settings through the IConfiguration interface, to do so, create a new constructor that asks for the IConfiguration type through parameters, assign the IConfiguration parameter to a field and then use it as in the following code to get the data from your config file in this example its appsettings.json,

    public class ExampleDbContext : DbContext
{
    private readonly IConfiguration _configuration;
    public ExampleDbContext(IConfiguration configuration)
    {
        _configuration = configuration;
        Console.WriteLine(_configuration["ConnectionStrings:DefaultConnection"]);
    }
    

    protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
        => optionsBuilder.UseSqlServer(_configuration["ConnectionStrings:DefaultConnection"]);
}

    To enable depency injection for our ExampleDbContext we can use the following code in our builder

    var builder = WebApplication.CreateBuilder(args);
//other services, middleware, etc.
builder.Services.AddDbContext<ExampleDbContext>();
var app = builder.Build();

    note: i tried the following code in asp.net minimal api’s and it worked. i am not sure about asp.net mvc version

    Login or Signup to reply.
  3. 0

    You should be able to use IConfiguration interface with registered settings from defined sources (appsettings.json in your case).

    So, during registration process, you just call:

    builder.Services.AddDbContext<ExampleDbContext>(options =>
    options.UseSqlServer(
        builder.Configuration.GetConnectionString("DefaultConnection")));
    Login or Signup to reply.
Please signup or login to give your own answer.

Back To Top
Search