c# - Entity Framework Include() 返回 null 导航属性

Question

我对 Include 函数有疑问。我有一个 Team 类，它有一个 Owner 类型的 Owner 属性。我有一个辅助函数来包装我的 EF 调用，如下所示；

public Task<List<T>> GetManyAsync(
    Expression<Func<T, bool>> filter = null,
    Expression<Func<T, object>> includeProperties = null)
{
    IQueryable<T> query = _dbSet;

    if (filter != null)
    {
        query = query.Where(filter);
    }

    if (InstanceHelper.IsSomething(includeProperties))
    {
        query.Include(includeProperties);
    }

    return query.ToListAsync();
}

我是这样用的

var teams = await DataAccess.Team.GetManyAsync(e => e.Owner.Id == userId, e => e.Owner);

但它会返回所有者属性为 NULL 的团队列表。知道我在这里缺少什么吗？

Answer 1

你必须从这里使用

public Task<List<T>> GetManyAsync(Expression<Func<T, bool>> filter = null, params Expression<Func<T, object>>[] includeProperties = null)
{
  foreach (var prop in includeProperties)
  query = query.Include(prop);
  ...
}

你可以有多个包含

GetManyAsync(filter ,p => p.prop1 ,p.prop2,...)