System.ArgumentNullException："值不能为空。(参数"连接字符串")" 2

Question

这一行在我的项目中导致错误:

options.UseSqlServer(Configuration.GetConnectionString("SchoolContext")));

错误:

系统。参数不能为空。(参数connectionString)

我在网上读了一堆类似的问题，我找不到一个有效的改变。似乎UseSqlServer()内部的参数返回null。这使我相信我有一个配置错误。

下面是我的Startup和json文件的代码:

using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.HttpsPolicy;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.EntityFrameworkCore;
using ContosoUniversity.Data;
namespace ContosoUniversity
{
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.AddRazorPages();
services.AddDbContext<SchoolContext>(options =>
options.UseSqlServer(Configuration.GetConnectionString("SchoolContext")));
services.AddDatabaseDeveloperPageExceptionFilter();
}
public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
{
if (env.IsDevelopment())
{
app.UseDeveloperExceptionPage();
app.UseMigrationsEndPoint();
}
else
{
app.UseExceptionHandler("/Error");
app.UseHsts();
}
app.UseHttpsRedirection();
app.UseStaticFiles();
app.UseRouting();
app.UseAuthorization();
app.UseEndpoints(endpoints =>
{
endpoints.MapRazorPages();
});
}
}
}

{
"ConnectionStrings": {
"DefaultConnection": "Server=(***;Database=***;Trusted_Connection=True;MultipleActiveResultSets=true"
},
"Logging": {
"LogLevel": {
"Default": "Information",
"Microsoft": "Warning",
"Microsoft.Hosting.Lifetime": "Information",
"Microsoft.EntityFrameworkCore.Database.Command": "Information"
}
},
"AllowedHosts": "*"
}

感谢任何帮助。谢谢。

Answer 1

您试图获得一个名为SchoolContext的连接字符串，但您在配置中只有一个名为DefaultConnection的连接字符串。所以要么修改你的代码:

services.AddDbContext<SchoolContext>(options =>
options.UseSqlServer(Configuration.GetConnectionString("DefaultConnection")));

或者修改你的配置:

{
"ConnectionStrings": {
"SchoolContext": "Server=....."
},
// etc...