没有给出与所需形式参数'options'相对应的参数 [英] There is no argument given that corresponds to the required formal parameter 'options'
问题描述
我正在开发.Net Core中的第一个应用程序.
I'm working on my first application in .Net Core.
由于某种原因，我收到此构建错误:
I'm getting this build error for some reason:
错误CS7036没有给出与"LakeViewContext.LakeViewContext(DbContextOptions< LakeViewContext>)''LakeView的所需形式参数"options"相对应的参数
Error CS7036 There is no argument given that corresponds to the required formal parameter 'options' of 'LakeViewContext.LakeViewContext(DbContextOptions<LakeViewContext>)' LakeView
我无法通过Google搜索或MS文档找到解决方案.
I wasn't able to find a solution through Google Search or MS documentation.
我的上下文类:
using LakeView.Models;
using Microsoft.EntityFrameworkCore;
namespace LakeView
{
public class LakeViewContext : DbContext
{
public LakeViewContext(DbContextOptions<LakeViewContext> options) : base(options)
{
}
public DbSet<HTMLElement> HTMLElements { get; set; }
public DbSet<CustomizedElement> CustomizedElements { get; set; }
public DbSet<TemplateFileType> TemplateFileTypes { get; set; }
public DbSet<StyleFile> StyleFiles { get; set; }
public DbSet<Template> Templates { get; set; }
public DbSet<Course> Courses { get; set; }
public DbSet<Page> Pages { get; set; }
public DbSet<HTML> HTMLs { get; set; }
public DbSet<Comment> Comments { get; set; }
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
modelBuilder.Entity<CustomizedElementTemplate>()
.HasKey(s => new { s.CustomizedElementId, s.TemplateId });
base.OnModelCreating(modelBuilder);
}
}
}
控制器类:
using LakeView.Models;
using LakeView.Models.ViewModels;
using Microsoft.AspNetCore.Mvc;
using System.Collections.Generic;
using System.Linq;
namespace LakeView.Controllers
{
public class CoursesController : Controller
{
private LakeViewContext db = new LakeViewContext();
public IActionResult Index()
{
ICollection<Course> courses = db.Courses.ToList();
return View(courses);
}
[HttpGet]
public IActionResult CreateCourse()
{
return View("CreateCourse");
}
[HttpPost]
[ValidateAntiForgeryToken]
public IActionResult CreateCourse(CreateCourseViewModel courseVM)
{
if (ModelState.IsValid)
{
Course newCourse = new Course()
{
CourseCode = courseVM.CourseCode,
CourseTitle = courseVM.CourseTitle,
MasterOU = int.Parse(courseVM.MasterOU)
};
db.Courses.Add(newCourse);
db.SaveChanges();
return RedirectToAction("Index");
}
return View("CreateCourse", courseVM);
}
}
}
((粗体文本在Visual Studio中带有下划线，并且具有相同的错误
(bold text is underlined in Visual Studio with the same error
"private LakeViewContext db = new LakeViewContext ();"
"private LakeViewContext db = new LakeViewContext();"
启动类:
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Logging;
using LakeView.Models;
namespace LakeView
{
public class Startup
{
// This method gets called by the runtime. Use this method to add services to the container.
// For more information on how to configure your application, visit https://go.microsoft.com/fwlink/?LinkID=398940
public void ConfigureServices(IServiceCollection services)
{
services.AddMvc();
var connection = @"Data Source = (localdb)\MSSQLLocalDB; Database = LakeViewData; Trusted_Connection = True;";
services.AddDbContext<LakeViewContext>(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, ILoggerFactory loggerFactory)
{
//loggerFactory.AddConsole();
if (env.IsDevelopment())
{
app.UseDeveloperExceptionPage();
}
app.UseStaticFiles();
app.UseMvcWithDefaultRoute();
}
}
}
推荐答案
LakeViewContext期望将DbContextOptions<LakeViewContext>传递到其构造函数中.但是，您在不提供任何内容的情况下调用了构造函数:
LakeViewContext expects a DbContextOptions<LakeViewContext> to be passed into its constructor. However, you are calling the constructor without providing anything:
private LakeViewContext db = new LakeViewContext();
要解决此问题，您只需插入已设置的Dependency Injection系统即可.为此，请按如下所示更改您的控制器:
To fix the issue, you can just plug into the Dependency Injection system that you've set up. To do this, change your controller as follows:
public class CoursesController : Controller
{
private readonly LakeViewContext db;
public CoursesController(LakeVieContext db)
{
this.db = db;
}
...
ASP.NET核心依赖注入系统将在构造函数中为您提供LakeViewContext-只需使用它即可.
The ASP.NET Core Dependency Injection system will provide you with a LakeViewContext in the constructor - Just use that.
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