LINQ to XML 选择类似于 SQL IN 子句的元素

Question

我有一些 XML 包含付款信息，包括应用付款的发票的详细信息。例如，我想使用 LINQ to XML 仅收集应用于某些发票 (111,222,333) 的付款。如果是 SQL 我可以使用 IN (111,222,333) 关键字，但我不确定如何在 LINQ 中执行相同的操作。

<Payment>
    <PaymentId>1</PaymentId>
    <Total>50</Total>
    <Invoice>
        <Id>111</Id>
        <Amount>20</Amount>
    </Invoice>
    <Invoice>
        <Id>555</Id>
        <Amount>30</Amount>
    </Invoice>
</Payment>
<Payment>
    <PaymentId>2</PaymentId>
    <Total>20</Total>
    <Invoice>
        <Id>222</Id>
        <Amount>20</Amount>
    </Invoice>
</Payment>
<Payment>
    <PaymentId>3</PaymentId>
    <Total>80</Total>
    <Invoice>
        <Id>888</Id>
        <Amount>80</Amount>
    </Invoice>
</Payment>

LINQ

var result = xml.Select(x => x.Element("Payment"))
               Where(x => x.Element("Id").Value.Contains("111","222","333"))

在这个例子中，我想 select "PaymentId 1" 和 "PaymentId 2" 因为它们适用于 ID 匹配 111、222 或 333 的发票。

Answer 1

您可以对这些众所周知的 Is 的列表进行 match/intersect。

List<string> ids = new List<string> { "111", "222", "333" };

var result = xml
    .Elements("Payment")
    .Where(p => {
        var invoiceIds = p.Elements("Invoice").Elements("Id").Select(o => o.Value);
        return ids.Intersect(invoiceIds).Any();
    }
);

完整代码和NetFiddle。

const string XML = @"
    <root>
        <Payment>
            <PaymentId>1</PaymentId>
            <Total>50</Total>        
            <Invoice>
                <Id>555</Id>
                <Amount>30</Amount>
            </Invoice>
            <Invoice>
                <Id>111</Id>
                <Amount>30</Amount>
            </Invoice>
        </Payment>
        <Payment>
            <PaymentId>2</PaymentId>
            <Total>20</Total>
            <Invoice>
                <Id>222</Id>
                <Amount>20</Amount>
            </Invoice>
        </Payment>
        <Payment>
            <PaymentId>3</PaymentId>
            <Total>80</Total>
            <Invoice>
                <Id>888</Id>
                <Amount>80</Amount>
            </Invoice>
        </Payment>
    </root>
    ";

XElement xml = XElement.Parse(XML);
List<string> ids = new List<string> { "111", "222", "333" };

var result = xml
    .Elements("Payment")
    .Where(p => {
        var invoiceIds = p.Elements("Invoice").Elements("Id").Select(o => o.Value);
        return ids.Intersect(invoiceIds).Any();
        }
    );

foreach (var item in result)
{
    Console.WriteLine("PaymentId: {0}", (string)item.Element("PaymentId"));
}

LINQ to XML 选择类似于 SQL IN 子句的元素

LINQ to XML selecting elements similar to SQL IN clause

c#

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