使用IEqualityComparer来基于C＃中的两个属性生成一个不同的列表

当前，您Distinct()在FamilySelector实例集合上运行，其结果是通过引用相等性进行比较。

要正确执行此操作，您应传递一个实例IEqualityComparer来Distinct()调用：

var source = _mfgOrdersData
    .Select(o => new FamilySelector(o.ItemWrapper.ItemClass, o.ItemWrapper.Family))
    .Distinct(new FamilySelector())
    .OrderBy(f => f.CodeFamily)
    .ToList();

您应该在FamilySelector类中添加无参数构造函数，以便可以编译代码。

我还建议对FamilySelector类进行少量重构。当前，它保存数据并执行比较。通常，IEqualityComparer的实现是一个无数据类，仅执行比较：

class FamilyData
{
    public FamilyData(string code, string family)
    {
        Code = code;
        Family = family;
    }

    public string Code { get; set; }
    public string Family { get; set; }
    public string CodeFamily { get { return string.Format("{0}\t{1}", Code, Family); } }
}

class FamilySelector : IEqualityComparer<FamilyData>
{
    public bool Equals(FamilyData x, FamilyData y)
    {
        return x.Code == y.Code && x.Family == y.Family;
    }

    public int GetHashCode(FamilyData obj)
    {
        return obj.Code.GetHashCode() ^ obj.Family.GetHashCode();
    }
}

var source = _mfgOrdersData
    .Select(o => new FamilyData(o.ItemWrapper.ItemClass, o.ItemWrapper.Family))
    .Distinct(new FamilySelector())
    .OrderBy(f => f.CodeFamily)
    .ToList();