如何为 XML 元素之间的数据编写 linq-to-xml？

发布于 2025-01-07 07:08:58 字数 1353 浏览 4 评论 0原文

我正在尝试解析一些类似于以下内容的 XML：

<document>
    <headings>
        Important heading stuff.
    </headings>
    <startGroup group="1" />
        <startItem value="1" />Item one stuff<endItem />
        <blockofdata>
            <startItem value="2" />Item two stuff<endItem />
            <startItem value="3" />Item three stuff<endItem />
        </blockofdata>
        <startItem value="4" />Item four stuff<endItem />
    <endGroup />
    <startGroup group="2" />
        <startItem value="1" />Item one stuff<endItem />
        <startItem value="2" />Item two stuff<endItem />
        <startItem value="3" />Item three stuff<endItem />
    <endGroup />
</document>

我无法找出 linq-to-xml 语句来获取我想要的内容。我需要扁平化结构。因此，假设上面的 XML，我想获取此 POCO 的列表：

class Items
{
    public int GroupNumber {get;set;} // group property of startGroup
    public int ItemNumber {get;set;} // value property of startItem
    public string ItemText {get;set;}  // data between i
}

How do you write a linq-to-xml statements that will pull the data between the attribute into the上面的项目，同时从 startGroup/endGroup 和之间获取数据startItem/endItem 之间的数据？我已经为此花费了几个小时，并且即将改用 XML 流读取器并以老式方式解析它。

原文

I am trying to parse some XML that looks similar to this:

<document>
    <headings>
        Important heading stuff.
    </headings>
    <startGroup group="1" />
        <startItem value="1" />Item one stuff<endItem />
        <blockofdata>
            <startItem value="2" />Item two stuff<endItem />
            <startItem value="3" />Item three stuff<endItem />
        </blockofdata>
        <startItem value="4" />Item four stuff<endItem />
    <endGroup />
    <startGroup group="2" />
        <startItem value="1" />Item one stuff<endItem />
        <startItem value="2" />Item two stuff<endItem />
        <startItem value="3" />Item three stuff<endItem />
    <endGroup />
</document>

I cannot figure out a linq-to-xml statement to get what I want. I need to flatten the structure. So assuming the above XML, I would like to get a list of this POCO:

class Items
{
    public int GroupNumber {get;set;} // group property of startGroup
    public int ItemNumber {get;set;} // value property of startItem
    public string ItemText {get;set;}  // data between i
}

How do you write a linq-to-xml statement that would pull the data between the attributes into the above item while grabing the data from between startGroup/endGroup and the data between startItem/endItem? I have burned up several hours on this and am about to just switch to using a XML stream reader and parsing it the old fashioned way.

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巨坚强 2025-01-14 07:08:58

这里的关键是使用 ElementsAfterSelf() 和 NodesAfterSelf() 方法来抓取兄弟节点以及 TakeWhile() 谓词来停止在适当的时候进行枚举。

首先是辅助方法：

public static Items ItemsFromStartItem(XElement start, XElement group)
{
    return new Items
    {
        GroupNumber = (int)group.Attribute("group"),
        ItemNumber = (int)start.Attribute("value"),
        ItemText = start.NodesAfterSelf()
            .TakeWhile(n => n.NodeType != XmlNodeType.Element
                         || ((XElement)n).Name != "endItem")
            .OfType<XText>()
            .Select(t => t.Value)
            .Single()
    };
}

public static IEnumerable<Items> ItemsFromBlockOfData(
    XElement block, XElement group)
{
    return block.Elements("startItem")
        .Select(start => ItemsFromStartItem(start, group));
}

以及神奇的查询。

var query = doc.Descendants("startGroup")
    .SelectMany(group => group.ElementsAfterSelf()
        .TakeWhile(e => e.Name != "endGroup")
        .SelectMany(e => e.Name == "startItem"
            ? new[] { ItemsFromStartItem(e, group) }
            : ItemsFromBlockOfData(e, group))
    );

现在我希望您没有自己设计这个 XML...这是一种真正可以将某人推向边缘的东西。 ;)

The key here is to use the ElementsAfterSelf() and NodesAfterSelf() methods to grab the sibling nodes along with the TakeWhile() predicate to stop enumerating at the appropriate times.

First the helper methods:

public static Items ItemsFromStartItem(XElement start, XElement group)
{
    return new Items
    {
        GroupNumber = (int)group.Attribute("group"),
        ItemNumber = (int)start.Attribute("value"),
        ItemText = start.NodesAfterSelf()
            .TakeWhile(n => n.NodeType != XmlNodeType.Element
                         || ((XElement)n).Name != "endItem")
            .OfType<XText>()
            .Select(t => t.Value)
            .Single()
    };
}

public static IEnumerable<Items> ItemsFromBlockOfData(
    XElement block, XElement group)
{
    return block.Elements("startItem")
        .Select(start => ItemsFromStartItem(start, group));
}

And the magic query.

var query = doc.Descendants("startGroup")
    .SelectMany(group => group.ElementsAfterSelf()
        .TakeWhile(e => e.Name != "endGroup")
        .SelectMany(e => e.Name == "startItem"
            ? new[] { ItemsFromStartItem(e, group) }
            : ItemsFromBlockOfData(e, group))
    );

Now I hope you did not design this XML yourself... this is the kind of stuff that can really push someone over the edge. ;)

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