C# 向此LINQ to XML代码添加条件/筛选器

我有一个XML字符串“booms”：

将XML转换为以下字符串：

name: John
address: New York City

name: Daniel
address: Los Angeles

name: Joe
address: Chicago

---

问题：

如何将LINQ更改为过滤掉满足某些条件的动臂？例如，我如何筛选出地址包含“New”的繁荣期？在本例中，这将给出字符串：

name: John
address: New York City

---

但代码不应仅限于“包含”过滤器。

如果条件限制为相等

Dictionary<string, string> conditions = new Dictionary<string, string> { { "name", "John" } };

XDocument document = XDocument.Load(new StringReader(xmlString));

var booms = from boomElement in document.Descendants("boom")
            where conditions.All(condition => (string)boomElement.Element(condition.Key) == condition.Value)  // Where is used to filter the result
            let boomChildren = (from boomElementChild in boomElement.Elements()
                                select String.Format("{0}: {1}",
                                                     boomElementChild.Name.LocalName,
                                                     boomElementChild.Value))
            select String.Join(Environment.NewLine, boomChildren);
var result = String.Join(Environment.NewLine + Environment.NewLine, booms);

Dictionary conditions=新字典{{“name”，“John”}；
XDocument document=XDocument.Load（新的StringReader（xmlString））；
var booms=来自document.substands（“boom”）中的boomElement
where conditions.All（condition=>（string）boomElement.Element（condition.Key）==condition.Value）//where用于过滤结果
让boomChildren=（来自boomElement.Elements（）中的boomElementChild）
选择String.Format（“{0}:{1}”，
boomElementChild.Name.LocalName，
boomElementChild.Value）
选择String.Join（Environment.NewLine，boomChildren）；
var result=String.Join（Environment.NewLine+Environment.NewLine，booms）；

如果不限于equal（包含、等于），则必须创建一个表示条件的结构

// I've made Condition an abstract class to super any kind of condition.
// Just derive this class with the condition you want (And, Or, Equal, <=, IsNumber, ...)
public abstract class Condition
{
    // A condition is defined by this method. Because a condition is basically: "Does the specified value satisfy the condition?"
    public abstract bool Satisfy(string valueToTest);  
}

// This is the first example of condition.
// I wanted to make the condition immutable (readonly) not to be able to change them.
// So, all parameters of the condition are set during the construction.
public sealed class EqualCondition : Condition
{
    private readonly string value;
    public string Value { get { return value; } }

    public EqualCondition(string value)
    {
        this.value = value;
    }

    public override bool Satisfy(string valueToTest)
    {
        return value == valueToTest;  // Equals condition...
    }
}
public sealed class ContainCondition : Condition
{
    private readonly string value;
    public string Value { get { return value; } }

    public ContainCondition(string value)
    {
        this.value = value;
    }

    public override bool Satisfy(string valueToTest)
    {
        return valueToTest.Contains(valueToTest);  // Contains condition
    }
}

// The dictionary is used to list the conditions applied to each element.
Dictionary<string, Condition> conditions = new Dictionary<string, Condition> { { "name", new EqualCondition("John") } };  
XDocument document = XDocument.Load("test.xml");

var booms = from boomElement in document.Descendants("boom")
            // The next line check where all conditions are satisfied for the corresponding elements
            where conditions.All(condition => condition.Value.Satisfy((string)boomElement.Element(condition.Key)))
            let boomChildren = (from boomElementChild in boomElement.Elements()
                                select String.Format("{0}: {1}",
                                                        boomElementChild.Name.LocalName,
                                                        boomElementChild.Value))
            select String.Join(Environment.NewLine, boomChildren);
var result = String.Join(Environment.NewLine + Environment.NewLine, booms);

//我已将Condition作为一个抽象类，用于对任何类型的Condition进行超级处理。
//只需使用所需的条件（And或Equal，condition.Value.sulfit（（string）boomElement.Element（condition.Key）））派生此类
让boomChildren=（来自boomElement.Elements（）中的boomElementChild）
选择String.Format（“{0}:{1}”，
boomElementChild.Name.LocalName，
boomElementChild.Value）
选择String.Join（Environment.NewLine，boomChildren）；
var result=String.Join（Environment.NewLine+Environment.NewLine，booms）；

尚未对此进行测试，但请尝试以下操作：

//string xmlString = ...;
XDocument document = XDocument.Load(new StringReader(xmlString));

var booms = from boomElement in document.Descendants("boom").Where(x => true)
            let boolChildren = (from boomElementChild in boomElement.Elements()
                                select String.Format("{0}: {1}",
                                                     boomElementChild.Name.LocalName,
                                                     boomElementChild.Value))
            select String.Join(Environment.NewLine, boolChildren);
var result = String.Join(Environment.NewLine + Environment.NewLine, booms);

---

将true替换为您在x上的测试。

我强烈键入以下内容：

public class Boom
{
    string Name { get; set; }
    string Address { get; set; }
    public override string ToString()
    {
        return string.Format("Name: {0}{1}Address: {2}, Name, Environment.NewLine, Address);
    }
}

因此，您的查询将更改为：

XDocument document = XDocument.Load(new StringReader(xmlString));
var booms = 
    document.Descendants("boom")
            .Select(x => new Boom { Name = x.Element("name").Value,
                                    Address = x.Element("address").Value })
            .Where(b => /*filter here!*/);

---

你能提供这样一个一般结构的例子吗？例如，假设地址是地址——一个逗号分隔的子字符串（多个地址）——我想匹配其中一个子字符串。有可能吗？@roger.james如果我没弄错的话，当然可以。这只是字符串比较；您可能只需要使用

address.Split（“，”）

。要查找与条件匹配的地址，请使用

address.Split（“，”）。其中（…）

。抱歉，我们中的一些人对这些问题的看法不同。@Katana314我不明白你的意思。你在哪里看到“，”@CédricBignon这是他的评论请求。例如，假设地址是地址——一个逗号分隔的子字符串。一个大型的、可扩展的基于类的系统可能是他想要的，但我刚刚指出了他将如何在LINQ表达式中内联实现它。他在评论中要求支持

boom

元素中的任何类型的元素。我不知道的不仅仅是

姓名

或

地址

@CédricBignon，而且由于OP没有在他的OP中指出这一点，因此没有得到确认。也许他的要求变了？我不知道。至少，现在，他有了选择。

public class Boom
{
    string Name { get; set; }
    string Address { get; set; }
    public override string ToString()
    {
        return string.Format("Name: {0}{1}Address: {2}, Name, Environment.NewLine, Address);
    }
}

XDocument document = XDocument.Load(new StringReader(xmlString));
var booms = 
    document.Descendants("boom")
            .Select(x => new Boom { Name = x.Element("name").Value,
                                    Address = x.Element("address").Value })
            .Where(b => /*filter here!*/);