How can I get the first element after an element w

问题:

With this code I can get the title out of the following XML file:

var xml = XElement.Load (@"C:\\test\\smartForm-customersMain.xml");
string title = xml.Element("title").Value;

But how do I make it more exact, e.g. "get the first element after the smartForm element, e.g. something like this:

//PSEUDO-CODE:
string title = xml.Element("smartForm").FirstChild("title");

The XML:

<?xml version="1.0" encoding="utf-8" ?>
<smartForm idCode="customersMain">
    <title>Customers Main222</title>
    <description>Generic customer form.</description>
    <area idCode="generalData" title="General Data">
        <column>
            <group>
                <field idCode="anrede">
                    <label>Anrede</label>
                </field>
                <field idCode="firstName">
                    <label>First Name</label>
                </field>
                <field idCode="lastName">
                    <label>Last Name</label>
                </field>
            </group>
        </column>
    </area>
    <area idCode="address" title="Address">
        <column>
            <group>
                <field idCode="street">
                    <label>Street</label>
                </field>
                <field idCode="location">
                    <label>Location</label>
                </field>
                <field idCode="zipCode">
                    <label>Zip Code</label>
                </field>
            </group>
        </column>
    </area>
</smartForm>

回答1:

You want to use the Descendants axis method and then call the FirstOrDefault extension method to get the first element.

Here is a simple example:

using System;
using System.Linq;
using System.Xml.Linq;

class Program
{
    static void Main()
    {
        String xml = @"<?xml version=""1.0"" encoding=""utf-8"" ?>
            <smartForm idCode=""customersMain"">
                <title>Customers Main222</title>
                <description>Generic customer form.</description>
                <area idCode=""generalData"" title=""General Data"">
                <column>
                    <group>
                    <field idCode=""anrede"">
                        <label>Anrede</label>
                    </field>
                    <field idCode=""firstName"">
                        <label>First Name</label>
                    </field>
                    <field idCode=""lastName"">
                        <label>Last Name</label>
                    </field>
                    </group>
                </column>
                </area>
                <area idCode=""address"" title=""Address"">
                <column>
                    <group>
                    <field idCode=""street"">
                        <label>Street</label>
                    </field>
                    <field idCode=""location"">
                        <label>Location</label>
                    </field>
                    <field idCode=""zipCode"">
                        <label>Zip Code</label>
                    </field>
                    </group>
                </column>
                </area>
            </smartForm>";

        XElement element = XElement.Parse(xml)
            .Descendants()
            .FirstOrDefault();
    }
}

回答2:

To add slightly to Andrew's answer if you do not know whether smartForm is the root element but still want the title text of the first such entry you would use:

xml.DescendantsAndSelf("smartForm").Descendants("title").First().Value;

This requires that there be a smartForm element with a title element somewhere within it.

If you wanted to ensure that the title element was an immediate child in smartForm you could use:

xml.DescendantsAndSelf("smartForm").Elements("title").First().Value;

If you didn't care what the name of title was and just wanted the first sub element then you would use:

xml.DescendantsAndSelf("smartForm").Elements().First().Value;

回答3:

My task was to find first child of specified name. If xml uses namespaces, than instead of

e.Elements(name).FirstOrDefault()

Write

e.Elements().FirstOrDefault(i => i.Name.LocalName == name)