问题
I want to read just a connection string from a configuration file and for this add a file with the name "appsettings.json" to my project and add this content on it:
{
"ConnectionStrings": {
"DefaultConnection": "Server=(localdb)\\mssqllocaldb;Database=aspnet-
WebApplica71d622;Trusted_Connection=True;MultipleActiveResultSets=true"
},
"Logging": {
"IncludeScopes": false,
"LogLevel": {
"Default": "Debug",
"System": "Information",
"Microsoft": "Information"
}
}
}
On ASP.NET I used this:
var temp=ConfigurationManager.ConnectionStrings["DefaultConnection"].ConnectionString;
Now how can I read "DefaultConnection" in C# and store it on a string variable in .NET Core?
回答1:
You can do this with the GetConnectionString extension-method:
string conString = Microsoft
.Extensions
.Configuration
.ConfigurationExtensions
.GetConnectionString(this.Configuration, "DefaultConnection");
System.Console.WriteLine(conString);
or with a structured-class for DI:
public class SmtpConfig
{
public string Server { get; set; }
public string User { get; set; }
public string Pass { get; set; }
public int Port { get; set; }
}
Startup:
public IConfigurationRoot Configuration { get; }
// This method gets called by the runtime. Use this method to add services to the container.
public void ConfigureServices(IServiceCollection services)
{
// http://developer.telerik.com/featured/new-configuration-model-asp-net-core/
// services.Configure<SmtpConfig>(Configuration.GetSection("Smtp"));
Microsoft.Extensions.DependencyInjection.OptionsConfigurationServiceCollectionExtensions.Configure<SmtpConfig>(services, Configuration.GetSection("Smtp"));
And then in the home-controller:
public class HomeController : Controller
{
public SmtpConfig SmtpConfig { get; }
public HomeController(Microsoft.Extensions.Options.IOptions<SmtpConfig> smtpConfig)
{
SmtpConfig = smtpConfig.Value;
} //Action Controller
public IActionResult Index()
{
System.Console.WriteLine(SmtpConfig);
return View();
}
with this in appsettings.json:
"ConnectionStrings": {
"DefaultConnection": "Server=(localdb)\\mssqllocaldb;Database=aspnet-WebApplica71d622;Trusted_Connection=True;MultipleActiveResultSets=true"
},
"Smtp": {
"Server": "0.0.0.1",
"User": "user@company.com",
"Pass": "123456789",
"Port": "25"
}
回答2:
The posted answer is fine but didn't directly answer the same question I had about reading in a connection string. Through much searching I found a slightly simpler way of doing this.
In Startup.cs
public void ConfigureServices(IServiceCollection services)
{
...
// Add the whole configuration object here.
services.AddSingleton<IConfiguration>(Configuration);
}
In your controller add a field for the configuration and a parameter for it on a constructor
private readonly IConfiguration configuration;
public HomeController(IConfiguration config)
{
configuration = config;
}
Now later in your view code you can access it like:
connectionString = configuration.GetConnectionString("DefaultConnection");
回答3:
See link for more info: https://docs.microsoft.com/en-us/ef/core/miscellaneous/connection-strings
JSON
{
"ConnectionStrings": {
"BloggingDatabase": "Server=(localdb)\\mssqllocaldb;Database=EFGetStarted.ConsoleApp.NewDb;Trusted_Connection=True;"
},
}
C# Startup.cs
public void ConfigureServices(IServiceCollection services)
{
services.AddDbContext<BloggingContext>(options =>
options.UseSqlServer(Configuration.GetConnectionString("BloggingDatabase")));
}
回答4:
The way that I found to resolve this was to use AddJsonFile in a builder at Startup (which allows it to find the configuration stored in the appsettings.json file) and then use that to set a private _config variable
public Startup(IHostingEnvironment env)
{
var builder = new ConfigurationBuilder()
.SetBasePath(env.ContentRootPath)
.AddJsonFile("appsettings.json", optional: true, reloadOnChange: true)
.AddJsonFile($"appsettings.{env.EnvironmentName}.json", optional: true)
.AddEnvironmentVariables();
_config = builder.Build();
}
And then I could set the configuration string as follows:
var connectionString = _config.GetConnectionString("DbContextSettings:ConnectionString");
This is on dotnet core 1.1
回答5:
i have a data access library which works with both .net core and .net framework.
the trick was in .net core projects to keep the connection strings in a xml file named "app.config" (also for web projects), and mark it as 'copy to output directory',
<?xml version="1.0" encoding="utf-8"?>
<configuration>
<connectionStrings>
<add name="conn1" connectionString="...." providerName="System.Data.SqlClient" />
</connectionStrings>
</configuration>
ConfigurationManager.ConnectionStrings - will read the connection string.
var conn1 = ConfigurationManager.ConnectionStrings["conn1"].ConnectionString;
回答6:
You can use configuration extension method : getConnectionString ("DefaultConnection")
https://docs.asp.net/projects/api/en/latest/autoapi/Microsoft/Extensions/Configuration/ConfigurationExtensions/index.html#Microsoft.Extensions.Configuration.ConfigurationExtensions.GetConnectionString
来源:https://stackoverflow.com/questions/59712781/could-not-load-file-or-assembly-system-configuration-configurationmanager-in