ASP.NET Core 2.x OnConfiguring get connectionstring string from appsettings.json

Question

Just started messing with ASP.NET Core, pretty impressive so far. In the code generated,(see below). I want to change the hardcoded connection string to get it from the appsettings.json file.

This is apparently impossible. I haven't found a single example that works (or even builds).

What's going on?? Please help

    protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
    {
        if (!optionsBuilder.IsConfigured)
        {
#warning To protect potentially sensitive information in your connection string, you should move it out of source code. See http://go.microsoft.com/fwlink/?LinkId=723263 for guidance on storing connection strings.
            optionsBuilder.UseSqlServer("Server=xxxxxxx;Database=xxxxx;Trusted_Connection=True;");
        }
    }

The link provided solves the problem in one area but doesn't work here in OnConfiguring. What am I doing wrong ?

public class Startup
{
    public Startup(IConfiguration configuration)
    {
        Configuration = configuration;
    }

    public IConfiguration Configuration { get; }

    // This method gets called by the runtime. Use this method to add services to the container.
    public void ConfigureServices(IServiceCollection services)
    {
        services.Configure<CookiePolicyOptions>(options =>
        {
            // This lambda determines whether user consent for non-essential cookies is needed for a given request.
            options.CheckConsentNeeded = context => true;
            options.MinimumSameSitePolicy = SameSiteMode.None;
        });

        services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_1);

        var connection = Configuration.GetConnectionString("ConnectionName");
        services.AddDbContext<SurveyContext>(options => options.UseSqlServer(connection));
    }

    // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
    public void Configure(IApplicationBuilder app, IHostingEnvironment env)
    {
        if (env.IsDevelopment())
        {
            app.UseDeveloperExceptionPage();
        }
        else
        {
            app.UseExceptionHandler("/Home/Error");
            app.UseHsts();
        }

        app.UseHttpsRedirection();
        app.UseStaticFiles();
        app.UseCookiePolicy();

        app.UseMvc(routes =>
        {
            routes.MapRoute(
                name: "default",
                template: "{controller=Home}/{action=Index}/{id?}");
        });
    }
}

is this function in your DB context? and what code exactly did you generate? can you provide the steps you took? — Neville Nazerane, Oct 30 '18 at 20:03
check this https://learn.microsoft.com/en-us/aspnet/core/fundamentals/configuration/?view=aspnetcore-2.1 — Neville Nazerane, Oct 30 '18 at 20:06
Nope not my code, generated by VS2017 using `Scaffold-DbContext` command in package manager window — djack109, Oct 30 '18 at 20:06
when you use the `Scaffold-DbContext` option you should be getting a documentation url at the top of your `DbContext` class. did you check that? — Neville Nazerane, Oct 30 '18 at 20:07
for clarity for readers, do update your question saying you used `Scaffold-DbContext` for code generation — Neville Nazerane, Oct 30 '18 at 20:08
@NevilleNazerane yep checked that, doesn't help. I can't seem to find a way to get at the appsettings.json file through any methods — djack109, Oct 30 '18 at 20:08

score 2 · Answer 1 · answered Oct 30 '18 at 20:20

2

In the startup class of a .NET Core project you usually register this in the ConfigureServices function.

public void ConfigureServices(IServiceCollection services)
{
    services.AddDbContext<YourContext>(options => options.UseSqlServer(connection));
}

When you are in the startup class of a .NET Core it is no problem to read the values from appsettings.json.

You could read more at Microsoft, i.e. here: https://learn.microsoft.com/en-us/ef/core/get-started/aspnetcore/existing-db

answered Oct 30 '18 at 20:20

Karl Fridlund

21
2

yep did exactly that, put a breakpoint on the line, doesn't even get there – djack109 Oct 30 '18 at 20:22
@djack109 Can you show me how your startup-class lookes like and where the startup-class is called? From there I'm sure I can help you – Karl Fridlund Oct 30 '18 at 20:24
added to my original post – djack109 Oct 30 '18 at 20:27
I looked in your code for Startup and can't see any problems instantly from that. But what exactly happens, do you come into ConfigureServices or Configure function? If not I'm pretty sure the problems is outside of the Startup-class. @djack109 – Karl Fridlund Oct 30 '18 at 20:37
Deleted the `ConfigureServices` I think that was the cause of my problems – djack109 Oct 30 '18 at 20:41
Okey, hope you were able to sort it out! – Karl Fridlund Oct 30 '18 at 20:46

score 1 · Accepted Answer · answered Oct 30 '18 at 20:00

1

In the place where you want to access the appsettings.json,

JToken jAppSettings = JToken.Parse( 
      File.ReadAllText(Path.Combine(Environment.CurrentDirectory, 
      "appsettings.json")));

Now since you have the object, you can access its contents. Let me know if it works.

answered Oct 30 '18 at 20:00

Minu

232
4
13

if this is what he is trying to do, i would recommend using IConfiguration instead. it is already a json phrased string https://learn.microsoft.com/en-us/aspnet/core/fundamentals/configuration/?view=aspnetcore-2.1 – Neville Nazerane Oct 30 '18 at 20:06
@NevilleNazerane nope, that doesn't help either – djack109 Oct 30 '18 at 20:10
@Minu this is the closest I found so far, at least in brongs the contents back. I just need a robust way of getting the contents out :) – djack109 Oct 30 '18 at 20:11
`IConfiguration` is the best way to access the information. it is clean and easy. but you need to understand how dependency injections work first https://learn.microsoft.com/en-us/aspnet/core/fundamentals/dependency-injection?view=aspnetcore-2.1 – Neville Nazerane Oct 30 '18 at 20:17
this works`string conn = jAppSettings.SelectToken("ConnectionStrings").SelectToken("ConnectionName").Value();` – djack109 Oct 30 '18 at 20:17
1

the tricky thing about .net core is you need to understand an array of concepts before using it well – Neville Nazerane Oct 30 '18 at 20:18
@NevilleNazerane I get that. What I don't get is everything was working in say Asp.Net framework, why make things 10x harder – djack109 Oct 30 '18 at 20:21
Please do mark as answer if you think it helped you achieve the results @djack109 – Minu Oct 30 '18 at 20:21
the first time i set up `Scaffold-DbContext` it took me hours before i understood the setup. but once i did things are much cleaner and easier than .net framework – Neville Nazerane Oct 30 '18 at 20:24
1

This answer might have "worked", but I dont think its the right solution. Like @NevilleNazerane said, you need to use `IConfiguration`. You will have to make sure its generated correctly and u use the right path to your connection string. – Gerald Chifanzwa Oct 31 '18 at 09:40

Neville Nazerane · Answer 3 · 2018-10-30T20:32:07.580

1

When you use the Scaffold-DbContext, by default it hard codes your string into the DbContext class (so it works out of the box). You will need to register your DbContext in your startup class to proceed. To set this up, you can check the instructions in this answer.

Note that the Configuration property directly connects to your appsettings.json and several other locations. You can read more about it in this documentation. While you can always use the appsettings.json file, it is generally recommended to have your secure secrets in an external json file outside your source code. The best solution for this during development is using the secret manager. The easiest way to use this is right click on your project on visual studio and select "manage user secrets". This will open a json file that is already connected to your Configuration object.

Once this is set up, you need to use dependency injection to access your db context.

public class HomeController : Controller
{


     public HomeController(SurveyContext context)
     {
         // you can set the context you get here as a property or field
         // you can use visual studio's shortcut ctrl + . when the cursor is on "context"

         // you can then use the context variable inside your actions
     }
}

When you use using, it creates a new connection each time. Using injection makes sure only one connection is created per request no matter how many times it is used.

edited Oct 30 '18 at 20:32

answered Oct 30 '18 at 20:16

Neville Nazerane

6,622
3
46
79

Yep tried that too, as per the documentation. The code in `StartUp.cs` doesn't even get touched. – djack109 Oct 30 '18 at 20:19
doesn't get touched? how are you using your `DbContext`? – Neville Nazerane Oct 30 '18 at 20:21
in a using statement just like I have done for years with EF `using (var context = new SurveyContext())` – djack109 Oct 30 '18 at 20:23
once you have startup setup, you need to use your Db Context with dependency injections not using. check that link again, I will update my answer with how you need to use your db context – Neville Nazerane Oct 30 '18 at 20:27
I don't see in your answer where you are using DI in the controller to get at the data as opposed to a `using` statement – djack109 Oct 30 '18 at 20:35
the ` public HomeController(SurveyContext context)` portion is the DI. you can refresh the page if it is not visible – Neville Nazerane Oct 30 '18 at 20:36
Yep sorted, looks like my two methods we conflicting somewhere. The DI solution works – djack109 Oct 30 '18 at 20:40

ASP.NET Core 2.x OnConfiguring get connectionstring string from appsettings.json

3 Answers3