Question

代码：

XElement elem = XElement.Load("http://localhost:54002/sample.xml");

IEnumerable<List<String>> elem1 = (from member in elem.Elements("member")
                            where (String.Equals(member.Attribute("class").Value, "prem", StringComparison.OrdinalIgnoreCase))
                            select member.Elements("customer").Select(f => f.Value.ToString()).ToList());

 IEnumerable<string> out; // required output format
 foreach (List<string> temp in elem1)
        {
           out  = temp;
        }

sample.xml中

<root>
<member class="gold">
        <customer>cust3</customer>
        <customer>cust5</customer>
        <customer>cust8</customer>
        <customer>cust1</customer>
</member>
<member class="prem">
        <customer>cust5</customer>
        <customer>cust1</customer>
        <customer>cust3</customer>
        <customer>cust2</customer>
</member>
<member class="silver">
        <customer>cust5</customer>
        <customer>cust8</customer>
        <customer>cust1</customer>
        <customer>cust4</customer>
</member>
</root>

我需要以IEnumerable字符串格式返回linq输出而不使用foreach循环。简单来说，linq查询本身应返回所需的输出。

Answer 1

您可以在LINQ流利语法中使用SelectMany()直接返回List<string>：

IEnumerable<string> _out; // required output format
_out = elem.Elements("member")
           .Where(o => string.Equals(o.Attribute("class").Value, "prem", StringComparison.OrdinalIgnoreCase))
           .SelectMany(o => o.Elements("customer"))
           .Select(o => o.Value);

或者在查询语法中使用from子句两次返回相同的内容，例如：

IEnumerable<string> _out; // required output format
_out = (from member in elem.Elements("member")
        where String.Equals(member.Attribute("class").Value, "prem", StringComparison.OrdinalIgnoreCase)
        from customer in member.Elements("customer")
        select customer.Value);

<强> Dotnetfiddle Demo

转换IEnumerable <list <string>＆gt;没有第三个变量的IEnumerable <string>

1 个答案: