EF Core 2.1 下使用DI注入技巧

最近想学习 EF Core 的用法。根据网上其他人的文章和官方网站上的步骤操作后发现行不通。

我参考的是 https://docs.microsoft.com/en-us/ef/core/get-started/aspnetcore/existing-db

我的 DbContext没有无参构造方法

 

结果运行后报错：

 

An unhandled exception occurred while processing the request.

InvalidOperationException: No database provider has been configured for this DbContext. A provider can be configured by overriding the DbContext.OnConfiguring method or by using AddDbContext on the application service provider. If AddDbContext is used, then also ensure that your DbContext type accepts a DbContextOptions<TContext> object in its constructor and passes it to the base constructor for DbContext.

Microsoft.EntityFrameworkCore.Internal.DbContextServices.Initialize(IServiceProvider scopedProvider, IDbContextOptions contextOptions, DbContext context)

 

 

 

    // 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;
            });
            var dbbuilder = new DbContextOptionsBuilder<EcolDbContext>()
                .UseSqlServer(Configuration.GetConnectionString("BloggingDatabase"));
            services.AddDbContext<EcolDbContext>(options => options = dbbuilder);  
            services.AddScoped<EcolDbContext>((p) => { return new EcolDbContext(dbbuilder.Options); });

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

services.AddScoped<EcolDbContext>((p) => { return new EcolDbContext(dbbuilder.Options); }); 

 

 

 

是重点。利用.netcore自带的 依赖注入 功能注入 EcolDbContext。

 

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然后在Controller的构造函数里传入EcolDbContext

 

 

希望对大家有用。