通用存储库，函数解释/ c#

本文关键字：解释 函数 存储 | 更新日期: 2023-09-27 18:10:31

我发现了一些有趣的通用存储库，但我无法弄清楚函数的作用:performanmincludes (includeProperties, query);

调用performanminclations，

public T Single(Expression<Func<T, bool>> where, string includeProperties)
        {
            try
            {
                IQueryable<T> query = IDbSet;
                query = PerformInclusions(includeProperties, query);
                return query.Single(where);
            }
            catch (InvalidOperationException ex)
            {
                return null;
            }
        }

PerformInclusions 

private static IQueryable<T> PerformInclusions(string includeProperties,
                                                       IQueryable<T> query)
        {
            if (includeProperties != null && includeProperties.Length > 0)
            {
                foreach (var includeProperty in includeProperties.Split(new char[] { ',' }, StringSplitOptions.RemoveEmptyEntries))
                {
                    query = query.Include(includeProperty);
                }
            }
            return query;
        }

我可以使用不带第二个参数的单个函数。

Euser test = Adapter.EuserRepository.Single(u => u.EuserEmail.Equals(user.EuserEmail), "");

所以我有2个问题，函数performinclations()做什么，有人能给我一个例子，includeproperties会在调用single()函数。

Thanks in advance

通用存储库，函数解释/ c#

正如@Andrei所说，这允许您使用熟悉的EF include语法来快速加载导航属性。另一种快速加载nav属性的方法是通过lambdas，如下所示:

    public T GetBy(Expression<Func<T, bool>> predicate, params Expression<Func<T, object>>[] includes)
    {
        var result = GetAll();
        if (includes.Any())
        {
            foreach (var include in includes)
            {
                result = result.Include(include);
            }
        }
        return result.FirstOrDefault(predicate);
    }

如果你有一个具有如下导航属性的实体:

public class Test{
    public int Id {get;set;}
    public SomethingElse Thing {get;set;}
}

_repo.Single(t => t.Id == 1, "");或_repo.GetBy(t => t.Id == 1);

将返回一个Thing为null的实体

_repo.Single(t => t.Id == 1, "Thing"); OR _repo.GetBy(t => t.Id == 1, t=>t.Thing);

将返回一个实体，其中Thing通过外键

填充。

有关EF中导航属性的更多详细信息，请查看我的博客http://blog.staticvoid.co.nz/2012/7/17/entity_framework-navigation_property_basics_with_code_first

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