關於EFCore線程內惟一

EntityFramework的線程內惟一

EntityFramework的線程內惟一是經過httpcontext來實現的

public static DbContext DbContext()  
            {  
                DbContext dbContext = HttpContext.Current.Items["dbContext"] as DbContext;  
                if (dbContext == null)  
                {  
                    dbContext = new WebEntities();  
                    HttpContext.Current.Items["dbContext"] =  dbContext;  
                }  
                return dbContext;  
            }

EntityFrameworkCore的線程內惟一

咱們都知道.net Core的數據庫上下文對象是在容器裏註冊，在用到的時候經過依賴注入建立的，那要如何保證每次請求只建立一個對象呢？
咱們能夠在註冊的時候，經過設置ServiceLifetime屬性來達到目的。

services.AddDbContext<MyContext>(options =>
            {
                // var connectionString = Configuration["ConnectionStrings:DefaultConnection"];
                var connectionString = Configuration.GetConnectionString("DefaultConnection");
                options.UseSqlite(connectionString);
            },ServiceLifetime.Scoped);

經過查看AddDbContext這個方法咱們能夠發現，ServiceLifetime這個屬性默認就是每次請求建立一次

public static IServiceCollection AddDbContext<TContext>([NotNull] this IServiceCollection serviceCollection, [CanBeNull] Action<DbContextOptionsBuilder> optionsAction = null, ServiceLifetime                     contextLifetime = ServiceLifetime.Scoped, ServiceLifetime optionsLifetime = ServiceLifetime.Scoped) where TContext : DbContext
        {
            return serviceCollection.AddDbContext<TContext, TContext>(optionsAction, contextLifetime, optionsLifetime);
        }

因此咱們徹底不須要手動去指定(^▽^)