将 LINQ 转换为 XML

Question

<?xml version="1.0" encoding="UTF-8" ?>
<Accounts>
  <Account id="usama" password="3210" lastUpdated="6/16/2011 11:21:59 AM" nextUpdate="6/16/2011 11:36:59 AM">
    <SubAccount id="false">
      <Url>yahoo</Url>
      <Review>not so good</Review>
    </SubAccount>
    <SubAccount id="false">
      <Url>google</Url>
      <Review>as good as heard.</Review>
    </SubAccount>
  </Account>
</Accounts>

假设我想获取所有最后更新日期小于或等于今天（假设 6/17/2011）日期的结果。

所以我的结果应该是这样的。

Accout id =usama ,passwod =3210 ,url=yahoo, review=not so good
Accout id =usama ,passwod =3210 ,url=google, review=as good as heard

到目前为止，我已经编写了查询

var q = from c in doc.Descendants("Accounts")
        from a in c.Descendants("Account")
        where a.Attribute("nextUpdate").Value == "6/16/2011 11:36:59 AM"
        select new
               {                        
                 accountName = a.Attribute("id").Value,                       
                 password = a.Attribute("password").Value,                        
                 url = a.Descendants("SubAccount").Descendants("Url").ToString() 
                 //review=a.Attribute("nextUpdate").Value
               }

我可以正常获取用户名和密码，但我不知道如何获取 URL 和查看。另外如何将 where 子句中的 Attribute("nextUpdate") 转换为日期时间，以便我可以将其与日期进行比较？

Answer 1

试试这个（测试和工作）：

DateTime someTime = DateTime.Now;
var q = from a in doc.Descendants("Account")
        from sub in a.Elements("SubAccount")
        where (DateTime)a.Attribute("nextUpdate") <= someTime 
        select new
        {  
            accountName = a.Attribute("id").Value,  
            password = a.Attribute("password").Value,  
            url = (string)sub.Element("Url").Value,
            review = (string)sub.Element("Review").Value
        }

这使用了 Linq to XML 提供的 DateTime 转换（另见 here）。

Answer 2

这是我的建议。

var doc = XElement.Load(...);
var q =
    from account in doc.Elements("Account")
    let nextUpdate = XmlConvert.ToDateTime(account.Attribute("nextUpdate").Value, "your date format").Date
    where nextUpdate <= DateTime.Today
    from subAccount in account.Elements("SubAccount")
    select new
    { 
      Id = account.Attribute("id").Value,
      Password = account.Attribute("password").Value,
      Url = subAccount.Element("Url").Value,
      Review= subAccount.Element("Review").Value,
    }

不要忘记用适当的格式字符串替换“您的日期格式”。 http://msdn.microsoft.com/en-us/library/kzk5c6y9.aspx

Answer 3

这样的？

var q =
    from account in doc.Descendants("Account")
    from subAcount in account.Elements("SubAccount")
    where DateTime.Parse(account.Attribute("nextUpdate").Value) == filterDateTime
    select new
    {
        accountName = account.Attribute("id").Value,
        password = account.Attribute("password").Value,
        url = subAcount.Element("Url").Value,
        review = subAcount.Element("Review").Value
    };

filterDateTime 是DateTime 的变量。