Linq到对象复制删除

Question

我有这样的代码；

XElement TEST = XElement.Parse(
@"<SettingsBundle>
    <SettingsGroup Id=""QAVerificationSettings"">
        <Setting Id=""RegExRules"">True</Setting>
        <Setting Id=""RegExRules1""><RegExRule><Description>Foo</Description><IgnoreCase>false</IgnoreCase><RegExSource></RegExSource><RegExTarget>[^\s]+@[^\s]+</RegExTarget><RuleCondition>TargetOnly</RuleCondition></RegExRule></Setting>
        <Setting Id=""RegExRules2""><RegExRule><Description>Boo</Description><IgnoreCase>false</IgnoreCase><RegExSource></RegExSource><RegExTarget>\s{2,}</RegExTarget><RuleCondition>TargetOnly</RuleCondition></RegExRule></Setting>
        <Setting Id=""RegExRules2""><RegExRule><Description>Boo</Description><IgnoreCase>false</IgnoreCase><RegExSource></RegExSource><RegExTarget>\s{2,}</RegExTarget><RuleCondition>TargetOnly</RuleCondition></RegExRule></Setting>
    </SettingsGroup>
</SettingsBundle>");
List<XElement> LIST1 = new List<XElement> { };
foreach( XElement x in TEST.Descendants( "RegExRule"))
    LIST1.Add(x);
var LIST2 = LIST1.Distinct();           
var NEW = new XDocument(
    new XElement("SettingsBundle",
        new XElement("SettingsGroup", new XAttribute("Id", "QAVerificationSettings"),
            new XElement("Settings", new XAttribute("Id", "RegExRules"), "True"),
            LIST2.Select((x, i) => new XElement("Setting", new XAttribute("Id", "RegExRules" + i ), x ))
    )));
NEW.Save(Directory.GetCurrentDirectory() + @"\_Texting.xml");

我想删除同一项目之一（我只需要一个“ RegExRules2”，而不是两个）。

但是，都失败了。

我需要做什么 ？ （我想我不擅长使用“ Distinct（）”）

谢谢

Answer 1

您可以执行GroupBy并仅使用每个组中的第一项来获取不同的元素：

XNamespace ns = "http://schemas.datacontract.org/2004/07/Sdl.Verification.QAChecker.RegEx";

var distinctRules = TEST.Descendants(ns + "RegExRule")
                        .GroupBy(o => o.ToString())
                        .Select(o => o.First());
var result = new XDocument(
    new XElement("SettingsBundle",
        new XElement("SettingsGroup", new XAttribute("Id", "QAVerificationsettings"),
            new XElement("Settings", new XAttribute("Id", "RegExRules"), "True"),
            distinctRules.Select((x, i) => new XElement("Setting", new XAttribute("Id", "RegExRules" + i), x))
    )));

result.Save(Directory.GetCurrentDirectory() + @"\_Texting.xml");

Answer 2

另一种可能性是为XElement创建IEqualityComparer 。

一个非常基本的示例（您不应将其视为实现GetHashCode的好示例。请在此处查找 ）是：

public class XElementComparer : IEqualityComparer<XElement>
{

    public bool Equals(XElement x, XElement y)
    {
        return x.Parent.Attribute("Id").Value == y.Parent.Attribute("Id").Value;
    }

    public int GetHashCode(XElement obj)
    {
        string val = obj.Parent.Attribute("Id").Value;
        return val.GetHashCode();
    }
}

然后在您的Distinct操作中将如下所示： var LIST2 = LIST1.Distinct(new XElementComparer());