問題描述

我面臨的情況是使用 Linq 將 XML 文檔解析為對象.在解析過程中，我正在檢查以確保元素不為空，然后再繼續(xù)解析它們的值.有沒有辦法簡化這句話?

The situation I am faced with is parsing an XML document into an object using Linq. During the parse I am checking to make sure Elements are not null before proceeding to parse out their values. Is there anyway to simplify this statement?

  var variable = (from x in xdoc.Descendants("Root")
                 select new AccountingResponse
                 {      
                 NetCharge = x.Element("Charges") != null && x.Element("Charges").Element("NetCharge") != null ? x.Element("Charges").Element("NetCharge").Value : "0",
                 TotalCharge = x.Element("Charges") != null && x.Element("Charges").Element("TotalCharge") != null ? x.Element("Charges").Element("TotalCharge").Value : "0"
                 }).SingleOrDefault();

總而言之，我不想繼續(xù)檢查每行是否存在節(jié)點.我知道我可以在解析之前測試該節(jié)點是否存在，但可能還有其他數(shù)據(jù)需要解析以創(chuàng)建 AccountingResponse，我想避免一次只解析一部分 XML 的 if 語句.

To summarize, I do not want to continue to check if the nodes exist on each line. I know I can test to see if the node exists prior to the parsing, but there may be other data that needs parsed to create the AccountingResponse and I want to avoid if statements that only parse a portion of the XML out at a time.

或者也許我做錯了，有更好的方法！

Or perhaps I'm doing this completely wrong and there's a better way!

推薦答案

一個簡單的選擇是使用 Elements 而不是 Element - 這將返回一個零長度的序列如果元素不存在.所以你可以使用:

One simple option is to use Elements rather than Element - that will return a zero-length sequence if the element isn't present. So you can use:

from x in xdoc.Descendants("Root")
select new AccountingResponse
{      
    NetCharge = x.Elements("Charges")
                 .Elements("NetCharge")
                 .Select(y => (int) y)
                 .FirstOrDefault(),
    TotalCharge = x.Elements("Charges")
                   .Elements("TotalCharge")
                   .Select(y => (int) y)
                   .FirstOrDefault(),
}).SingleOrDefault();

(請注意，您的原始代碼不會編譯，因為 Value 是一個字符串，而 0 是一個 int...)

(Note that your original code wouldn't compile, as Value is a string whereas 0 is an int...)

這篇關(guān)于帶有檢查空元素的 XML 到 LINQ的文章就介紹到這了，希望我們推薦的答案對大家有所幫助，也希望大家多多支持html5模板網(wǎng)！