Linq到实体IncludeIf扩展 [英] Linq to Entities IncludeIf Extension

问题描述

在我的存储库中，我发现此线程的WhereIf Linq-to-sql扩展名(

In my repositories, I find that the WhereIf Linq-to-sql extension from this thread (LINQ to SQL Where Clause Optional Criteria) is very useful -- especially the IEnumerable version.

我想对Include()语句做同样的事情，但是我对编写扩展不是很好.我陷入了扩展名的声明.

I would like to do the same thing with the Include() statement, but I'm not very good with writing extensions. I got stuck on the declaration of the extension.

有人可以帮助我将WhereIf扩展名移植到IncludeIf吗?

Can anyone help me port the WhereIf extension to IncludeIf?

推荐答案

有两个 Include(...)，其中一个已经是 IQueryable< T> <的扩展方法./code>，它是 DbQuery< T> 的一种方法.这应该给您两个扩展 IncludeIf<>

There are two Include(...), one that is already an extension method to IQueryable<T> and one that is a method of DbQuery<T>. This should give you both extensions IncludeIf<>

public static class QueryableEx
{
    public static IQueryable<T> IncludeIf<T, TProperty>(this IQueryable<T> source, bool condition, Expression<Func<T, TProperty>> path) where T : class
    {
        if (condition)
        {
            return source.Include(path);
        }
        else
        {
            return source;
        }
    }

    public static DbQuery<TResult> IncludeIf<TResult>(this DbQuery<TResult> query, bool condition, string path)
    {
        if (condition)
        {
            return query.Include(path);
        }
        else
        {
            return query;
        }            
    }
}

请记住，您需要像我一样将它们放在静态类中.

Remember that you need to put them in a static class like I have done.

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