EF Core中的.Configuration.ProxyCreationEnabled等价于什么？ [英] What is the equivalent of .Configuration.ProxyCreationEnabled in EF Core?

问题描述

Entity Framework Core中.Configuration的等效项是什么？以下接收错误

What is the equivalent of .Configuration in Entity Framework Core? Receiving error below

代码示例：

        List<DocumentStatus> documentStatuses;
        using (var db = new ModelDBContext())
        {
            db.Configuration.ProxyCreationEnabled = false;
            documentStatuses = db.DocumentStatus.ToList();
        }


        using (var db = new ModelDBContext())
        {
            db.Configuration.ProxyCreationEnabled = false;
            //Expression<Func<Owner, bool>> predicate = query => true;

db.Configuration.ProxyCreationEnabled

db.Configuration.ProxyCreationEnabled

整个错误消息：

错误CS1061'ModelDBContext'不包含'Configuration'的定义并且没有可访问的扩展名可以找到接受 ModelDBContext类型的第一个参数的方法配置（您是否缺少using指令或程序集引用？）

Error CS1061 'ModelDBContext' does not contain a definition for 'Configuration' and no accessible extension method 'Configuration' accepting a first argument of type 'ModelDBContext' could be found (are you missing a using directive or an assembly reference?)

推荐答案

基于Entity Framework Core文档： https://docs.microsoft.com/zh-cn/ef/core/querying/related-data ，从EF Core 2.1开始，有一种方法可以启用带或不带代理的延迟加载

Based on Entity Framework Core docs: https://docs.microsoft.com/en-us/ef/core/querying/related-data, from EF Core 2.1, there is a way to enable Lazy Loading with or without proxy.

1。代理的延迟加载：

a。确保将导航属性定义为虚拟

a. Make sure your navigation property are defined as "virtual"

b。安装Microsoft.EntityFrameworkCore.Proxies软件包

b. Install the Microsoft.EntityFrameworkCore.Proxies package

c。通过调用UseLazyLoadingProxies启用它

c. Enable it with a call to UseLazyLoadingProxies

protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
    => optionsBuilder
        .UseLazyLoadingProxies()
        .UseSqlServer(myConnectionString);

或在使用AddDbContext时启用它

Or enable it when using AddDbContext

.AddDbContext<BloggingContext>(
    b => b.UseLazyLoadingProxies()
          .UseSqlServer(myConnectionString));

2。没有代理的延迟加载：

a。如实体类型构造器中所述，将ILazyLoader服务注入到实体中。例如：

a. Injecting the ILazyLoader service into an entity, as described in Entity Type Constructors. For example:

public class Blog
{
    private ICollection<Post> _posts;

    public Blog()
    {
    }

    private Blog(ILazyLoader lazyLoader)
    {
        LazyLoader = lazyLoader;
    }

    private ILazyLoader LazyLoader { get; set; }

    public int Id { get; set; }
    public string Name { get; set; }

    public ICollection<Post> Posts
    {
        get => LazyLoader.Load(this, ref _posts);
        set => _posts = value;
    }
}

---

默认情况下，EF Core不会对代理使用延迟加载，但是如果您要使用代理，请遵循第一种方法。

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