c# - Linq Complex OrderBy by Props 属性

Question

我有一个类，其中一些 Prop 标有一些属性。我想按特定顺序显示它们。到目前为止，我可以对它们进行排序，但不是我想要的顺序。

下面是一个简单的props属性示例

[IncludeInEditor]
[IsInPk]
ID
[IncludeInEditor(IsReadOnlyOnModify=true)]
Name
[IncludeInEditor]
Address
[IncludeInEditor]
DOB


The order that I want is:
  1st - Props with IsInPk attribute
  2nd - Props with IncludeInEditor(IsReadOnlyOnModify=true)
  3rd - Props with IncludeInEditor

到目前为止，我没有成功，也没有 100% 完成(仍然缺少 IsReadOnlyOnModify=true 部分)

var properties =
item.GetType().GetProperties()
.Where(p => p.GetCustomAttributes(true)
                            .OfType<IncludeInEditorAttribute>()
                            .Count() > 0)
                .Select (x => new 
                {
                    Property = x,
                    Attribute = (IsInPkAttribute)Attribute.GetCustomAttribute(x, typeof(IsInPkAttribute), true) 
                })
                .OrderBy(x => x.Attribute != null ? 1 : -1)
                .Select(x => x.Property)
                .ToArray();

Answer 1

您可以创建自己的 IComparer<T>比较每个属性的属性的实现:

public class AttributeComparer : IComparer<Attribute>
{
    public int Comparer(Attribute x, Attribute y)
    {
        if(x == null) return y == null ? 0 : -1;
        if(y == null) return 1;

        if(x is IsInPkAttribute) return (y is IsInPkAttribute) ? 0 : 1;
        else if(y is IsInPkAttribute) return -1;
        else
        {
            xa = (IncludeInEditorAttribute)x;
            ya = (IncludeInEditorAttribute)y;

            if(xa.IsReadOnlyOnModify == ya.IsReadOnlyOnModify) return 0;
            else return x.IsReadOnlyOnModify ? 1 : -1;
        }
    }
}

然后你的查询变成:

var properties = item.GetType().GetProperties()
    .Where(p => p.GetCustomAttributes(true)
                .OfType<IncludeInEditorAttribute>()
                .Any())
    .Select (x => new 
    {
        Property = x,
        Attribute = Attribute.GetCustomAttribute(x, typeof(IsInPkAttribute), true) ?? Attribute.GetCustomAttribute(x, typeof(IncludeInEditorAttribute, true))
    })
    .OrderBy(x => x.Attribute, new AttributeComparer())
    .Select(x => x.Property)
    .ToArray();