[英]Linq-to-XML query to select specific sub-element based on additional criteria
My current LINQ query and example XML are below. 我当前的LINQ查询和示例XML如下所示。 What I'd like to do is select the primary email address from the email-addresses element into the User.Email property. 我想要做的是从email-addresses元素中选择主电子邮件地址到User.Email属性。
What is the simplest approach to take here? 这里最简单的方法是什么?
Current Linq Query (User.Email is currently empty): 当前Linq查询(User.Email当前为空):
var users = from response in xdoc.Descendants("response")
where response.Element("id") != null
select new User
{
Id = (string)response.Element("id"),
Name = (string)response.Element("full-name"),
Email = (string)response.Element("email-addresses"),
JobTitle = (string)response.Element("job-title"),
NetworkId = (string)response.Element("network-id"),
Type = (string)response.Element("type")
};
Example XML: 示例XML:
<?xml version="1.0" encoding="UTF-8"?>
<response>
<response>
<contact>
<phone-numbers/>
<im>
<provider></provider>
<username></username>
</im>
<email-addresses>
<email-address>
<type>primary</type>
<address>alice@domain.com</address>
</email-address>
</email-addresses>
</contact>
<job-title>Account Manager</job-title>
<type>user</type>
<expertise nil="true"></expertise>
<summary nil="true"></summary>
<kids-names nil="true"></kids-names>
<location nil="true"></location>
<guid nil="true"></guid>
<timezone>Eastern Time (US & Canada)</timezone>
<network-name>Domain</network-name>
<full-name>Alice</full-name>
<network-id>79629</network-id>
<stats>
<followers>2</followers>
<updates>4</updates>
<following>3</following>
</stats>
<mugshot-url>
https://assets3.yammer.com/images/no_photo_small.gif</mugshot-url>
<previous-companies/>
<birth-date></birth-date>
<name>alice</name>
<web-url>https://www.yammer.com/domain.com/users/alice</web-url>
<interests nil="true"></interests>
<state>active</state>
<external-urls/>
<url>https://www.yammer.com/api/v1/users/1089943</url>
<network-domains>
<network-domain>domain.com</network-domain>
</network-domains>
<id>1089943</id>
<schools/>
<hire-date nil="true"></hire-date>
<significant-other nil="true"></significant-other>
</response>
<response>
<contact>
<phone-numbers/>
<im>
<provider></provider>
<username></username>
</im>
<email-addresses>
<email-address>
<type>primary</type>
<address>bill@domain.com</address>
</email-address>
</email-addresses>
</contact>
<job-title>Office Manager</job-title>
<type>user</type>
<expertise nil="true"></expertise>
<summary nil="true"></summary>
<kids-names nil="true"></kids-names>
<location nil="true"></location>
<guid nil="true"></guid>
<timezone>Eastern Time (US & Canada)</timezone>
<network-name>Domain</network-name>
<full-name>Bill</full-name>
<network-id>79629</network-id>
<stats>
<followers>3</followers>
<updates>1</updates>
<following>1</following>
</stats>
<mugshot-url>
https://assets3.yammer.com/images/no_photo_small.gif</mugshot-url>
<previous-companies/>
<birth-date></birth-date>
<name>bill</name>
<web-url>https://www.yammer.com/domain.com/users/bill</web-url>
<interests nil="true"></interests>
<state>active</state>
<external-urls/>
<url>https://www.yammer.com/api/v1/users/1089920</url>
<network-domains>
<network-domain>domain.com</network-domain>
</network-domains>
<id>1089920</id>
<schools/>
<hire-date nil="true"></hire-date>
<significant-other nil="true"></significant-other>
</response>
</response>
Using Lambda Expression: 使用Lambda表达式:
var users = xdoc.Root.Elements( "response" )
.Where( x => !string.IsNullOrEmpty( x.Element( "id" ).Value ) )
.Select( x => new User
{
Id = x.Element( "id" ).Value,
Name = x.Element( "full-name" ).Value,
Email = x.Descendants( "email-address" )
.Where( y => y.Element( "type" ).Value == "primary" )
.First().Element( "address" ).Value,
JobTitle = x.Element( "job-title" ).Value,
NetworkId = x.Element( "network-id" ).Value,
Type = x.Element( "type" ).Value,
} );
The Query Expression isn't much different: 查询表达式没有太大区别:
var users = from response in xdoc.Descendants( "response" )
where response.Element( "id" ) != null
select new User
{
Id = response.Element( "id" ).Value,
Name = response.Element( "full-name" ).Value,
Email = response.Descendants( "email-address" )
.Where( x => x.Element( "type" ).Value == "primary" )
.First().Element( "address" ).Value,
JobTitle = response.Element( "job-title" ).Value,
NetworkId = response.Element( "network-id" ).Value,
Type = response.Element( "type" ).Value
};
Like this: 像这样:
response.Descendants("email-address")
.Single(a => a.Element("type").Value == "primary")
.Element("address").Value
Note that this will throw an exception if there isn't exactly one matching element. 请注意,如果没有一个匹配元素,则会抛出异常。
If you don't want that, call FirstOrDefault
. 如果您不想这样,请致电FirstOrDefault
。
You might want to replace .Descendants("email-address")
with .Element("contact").Element("email-addresses").Element("email-address")
. 您可能希望将.Descendants("email-address")
替换为.Descendants("email-address")
.Element("contact").Element("email-addresses").Element("email-address")
。
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