.NET Core：如何设置连接字符串？

Question

我正在尝试使用Blazor的CRUD函数并遵循一些文章来执行此操作。在文章中，有一部分我应该将我的连接放在上下文文件中，但它没有说明如何设置连接字符串。

我将此代码行放在launchSettings.json中：

{
  "ConnectionStrings": {
    "UserDatabase": "Server=DESKTOP-2K2A6GN;Database=Assignment4;Trusted_Connection=True;"
  },
  "iisSettings": {
    "windowsAuthentication": false,
    "anonymousAuthentication": true,
    "iisExpress": {
      "applicationUrl": "http://localhost:56244/",
      "sslPort": 0
    }
  },
  "profiles": {
    "IIS Express": {
      "commandName": "IISExpress",
      "launchBrowser": true,
      "environmentVariables": {
        "ASPNETCORE_ENVIRONMENT": "Development"
      }
    },
    "Assignment4.Server": {
      "commandName": "Project",
      "launchBrowser": true,
      "environmentVariables": {
        "ASPNETCORE_ENVIRONMENT": "Development"
      },
      "applicationUrl": "http://localhost:56248/"
    }
  }
}

我试图将连接字符串添加到上下文文件中，但它不起作用。

public class UserContext : DbContext
    {
        public virtual DbSet<User> tblUser { get; set; }

        protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
        {
            if (!optionsBuilder.IsConfigured)
            {
                optionsBuilder.UseSqlServer(@"UserDatabase");
            }
        }
    }

Answer 1

连接字符串设置假设位于appsetting.json文件中。将文件添加到项目中

appsetting.json

{
  "ConnectionStrings": {
    "UserDatabase": "Server=DESKTOP-2K2A6GN;Database=Assignment4;Trusted_Connection=True;"
  }
}

更新DbContext以便可以配置它。

public class UserContext : DbContext {

    public UserContext(DbContextOptions<UserContext> options): base(options) {

    }

    public virtual DbSet<User> tblUser { get; set; }

}

您可以在Startup方法中的ConfigureServicesclass中配置DbContext。

public class Startup {

    public Startup(IHostingEnvironment env) {

        var builder = new ConfigurationBuilder()
            .SetBasePath(env.ContentRootPath)
            .AddJsonFile("appsettings.json");

        Configuration = builder.Build();
    }

    static IConfiguration Configuration { get; set; }

    public void ConfigureServices(IServiceCollection services) {    

        services.AddDbContext<UserContext>(options =>
            options.UseSqlServer(Configuration.GetConnectionString("UserDatabase"));
        );

        //...
    }

    // 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();
        }

        app.UseBlazor<Client.Program>();
    }
}

Answer 2

您可以更改文件UserContext.cs

public class DesignTimeDbContextFactory : IDesignTimeDbContextFactory<AppDbContext>
    {
        public UserContext CreateDbContext(string[] args)
        {
            IConfiguration configuration = new ConfigurationBuilder()
                .SetBasePath(Directory.GetCurrentDirectory())
                .AddJsonFile("appsettings.json").Build();
            var builder = new DbContextOptionsBuilder<AppDbContext>();
            var connectionString = configuration.GetConnectionString("UserDatabase");
            builder.UseSqlServer(connectionString);
            return new AppDbContext(builder.Options);
        }
    }

并在文件Startup.cs中

public void ConfigureServices(IServiceCollection services)
    {
        services.AddDbContext<UserContext>(options =>
               options.UseSqlServer(Configuration.GetConnectionString("UserDatabase"),
                   b => b.MigrationsAssembly("xxx.Data")));
    }