使用linq合并具有相同结构的多个XML文件并基于密钥删除重复项 [英] Using linq to merge multiple XML files with the same structure and removing duplicates based on a key

问题描述

我有多个XML文件，我正在尝试将其合并为一个文件. Linq to XML可能是最好的选择，但我愿意接受想法(XSLT似乎擅长合并两个文件，但笨拙，其中n> 2或n =大).

I have multiple XML files I'm trying to merge into a single file. Linq to XML is probably the best option but I'm open to ideas (XSLT seems good at merging TWO files but is clumsy where n > 2 or n = big).

从这里阅读其他问题，某种形式的联接看起来不错.

From reading other questions here, some sort of join looks good.

File1.xml:

File1.xml:

<first>
  <second>
    <third id="Id1">
      <values>
        <value a="1" b="one"/>
        <value a="2" b="two"/>
        <value a="3" b="three"/>
      </values>
    </third>
    <third id="Id2">
      <values>
        <value a="f" b="foo"/>
        <value a="b" b="bar"/>
        <value a="w" b="wibble"/>
      </values>
    </third>
  </second>
</first>

File2.xml:

File2.xml:

<first>
  <second>
    <third id="Id1">
      <values>
        <value a="2" b="two"/>
        <value a="3" b="three"/>
        <value a="6" b="six"/>
      </values>
    </third>
    <third id="Id3">
      <values>
        <value a="x" b="ex"/>
        <value a="y" b="why"/>
        <value a="z" b="zed"/>
      </values>
    </third>
  </second>
</first>

Merged.xml:

Merged.xml:

<first>
  <second>
    <third id="Id1">
      <values>
        <value a="1" b="one"/>
        <value a="2" b="two"/>
        <value a="3" b="three"/>
        <value a="6" b="six"/>
      </values>
    </third>
    <third id="Id2">
      <values>
        <value a="f" b="foo"/>
        <value a="b" b="bar"/>
        <value a="w" b="wibble"/>
      </values>
    </third>
    <third id="Id3">
      <values>
        <value a="x" b="ex"/>
        <value a="y" b="why"/>
        <value a="z" b="zed"/>
      </values>
    </third>
  </second>
</first>

即它将基于third/@ id属性合并值.

i.e. it merges the values based on the third/@id attribute.

我如何用linq优雅地做到这一点?

How do I do this elegantly with linq?

推荐答案

下面的内容仍然很丑陋，我相信可以通过一些工作使其变得更加精简，但是现在看来做这份工作:

The below is still quite ugly, and I am sure it could be brought into a somewhat more streamlined shape with a bit of work, but for now this seems to do the job:

public static void MergeXml()
{
    var xdoc1 = XDocument.Load(@"c:\temp\test.xml");
    var xdoc2 = XDocument.Load(@"c:\temp\test2.xml");
    var d1Targets = xdoc1.Descendants("third");
    var d2Selection = xdoc2.Descendants("third").ToList();

    Func<XElement, XElement, string, bool> attributeMatches = (x, y, a) =>
        x.Attribute(a).Value == y.Attribute(a).Value;

    Func<IEnumerable<XElement>, XElement, bool> hasMatchingValue = (ys, x) =>
        // remove && if matching "a" should cause replacement.
        ys.Any(d => attributeMatches(d, x, "a") && attributeMatches(d, x, "b"));

    foreach (var e in d1Targets)
    {
        var fromD2 = d2Selection.Find(x => attributeMatches(x, e, "id"));
        if (fromD2 != null)
        {
            d2Selection.Remove(fromD2);
            var dest = e.Descendants("value");
            dest.LastOrDefault()
                .AddAfterSelf(fromD2.Descendants("value").Where(x => !hasMatchingValue(dest, x)));
        }
    };
    if (d2Selection.Count > 0)
        d1Targets.LastOrDefault().AddAfterSelf(d2Selection);

    xdoc1.Save(@"c:\temp\merged.xml");
}

这将从OPs问题中的两个示例输入文件生成以下输出文件:

This produces the following output file from the two example input files in OPs question:

<?xml version="1.0" encoding="utf-8"?>
<first>
  <second>
    <third id="Id1">
      <values>
        <value a="1" b="one" />
        <value a="2" b="two" />
        <value a="3" b="three" />
        <value a="6" b="six" />
      </values>
    </third>
    <third id="Id2">
      <values>
        <value a="f" b="foo" />
        <value a="b" b="bar" />
        <value a="w" b="wibble" />
      </values>
    </third>
    <third id="Id3">
      <values>
        <value a="x" b="ex" />
        <value a="y" b="why" />
        <value a="z" b="zed" />
      </values>
    </third>
  </second>
</first>

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