使用 LINQ 分析 XML 以获取子元素
本文关键字：获取 元素 XML LINQ 分析 使用 | 更新日期: 2023-09-27 18:32:01
<?xml version="1.0" standalone="yes"?>
<CompanyInfo>
<Employee name="Jon" deptId="123">
<Region name="West">
<Area code="96" />
</Region>
<Region name="East">
<Area code="88" />
</Region>
</Employee>
</CompanyInfo>
public class Employee
{
public string EmployeeName { get; set; }
public string DeptId { get; set; }
public List<string> RegionList {get; set;}
}
public class Region
{
public string RegionName { get; set; }
public string AreaCode { get; set; }
}
我正在尝试读取此XML数据，到目前为止我已经尝试过：
XDocument xml = XDocument.Load(@"C:'data.xml");
var xElement = xml.Element("CompanyInfo");
if (xElement != null)
foreach (var child in xElement.Elements())
{
Console.WriteLine(child.Name);
foreach (var item in child.Attributes())
{
Console.WriteLine(item.Name + ": " + item.Value);
}
foreach (var childElement in child.Elements())
{
Console.WriteLine("--->" + childElement.Name);
foreach (var ds in childElement.Attributes())
{
Console.WriteLine(ds.Name + ": " + ds.Value);
}
foreach (var element in childElement.Elements())
{
Console.WriteLine("------->" + element.Name);
foreach (var ds in element.Attributes())
{
Console.WriteLine(ds.Name + ": " + ds.Value);
}
}
}
}
这使我能够获取每个节点，其属性名称和值，因此我可以将这些数据保存到数据库中的相关字段中，但这似乎是一个漫长的方式和不灵活，例如，如果 XML 结构更改了所有这些 foreach 语句需要重新访问，也很难以这种方式过滤数据，我需要编写某些 if 语句来过滤数据（例如，仅从西方获得员工等......
我一直在寻找一种更灵活的方法，使用 linq，如下所示：
List<Employees> employees =
(from employee in xml.Descendants("CompanyInfo")
select new employee
{
EmployeeName = employee.Element("employee").Value,
EmployeeDeptId = ?? get data,
RegionName = ?? get data,
AreaCode = ?? get data,,
}).ToList<Employee>();
但我不确定如何从子节点获取值并应用过滤（仅获取某些员工）。这可能吗？任何帮助，不胜感激。
谢谢
var employees = (from e in xml.Root.Elements("Employee")
let r = e.Element("Region")
where (string)r.Attribute("name") == "West"
select new Employee
{
EmployeeName = (string)e.Attribute("employee"),
EmployeeDeptId = (string)e.Attribute("deptId"),
RegionName = (string)r.Attribute("name"),
AreaCode = (string)r.Element("Area").Attribute("code"),
}).ToList();
但是，当 XML 文件结构更改时，它仍然需要修改查询。
编辑
查询每个员工的多个区域：
var employees = (from e in xml.Root.Elements("Employee")
select new Employee
{
EmployeeName = (string)e.Attribute("employee"),
DeptId = (string)e.Attribute("deptId"),
RegionList = e.Elements("Region")
.Select(r => new Region {
RegionName = (string)r.Attribute("name"),
AreaCode = (string)r.Element("Area").Attribute("code")
}).ToList()
}).ToList();
然后，您可以仅筛选来自给定区域的员工列表：
var westEmployees = employees.Where(x => x.RegionList.Any(r => r.RegionName == "West")).ToList();
您可以跟踪结构：
from employee in xml
.Element("CompanyInfo") // must be root
.Elements("Employee") // only directly children of CompanyInfo
或不太严格
from employee in xml.Descendants("Employee") // all employees at any level
然后获取所需的信息：
select new Employee
{
EmployeeName = employee.Attribute("name").Value,
EmployeeDeptId = employee.Attribute("deptId").Value,
RegionName = employee.Element("Region").Attribute("name").Value,
AreaCode = employee.Element("Region").Element("Area").Attribute("code").Value,
}
对于有关多个区域的其他信息，假设属性List<Region> Regions：
select new Employee
{
EmployeeName = employee.Attribute("name").Value,
EmployeeDeptId = employee.Attribute("deptId").Value,
//RegionName = employee.Element("Region").Attribute("name").Value,
//AreaCode = employee.Element("Region").Element("Area").Attribute("code").Value,
Regions = (from r in employee.Elements("Region") select new Region
{
Name = r.Attribute("name").Value,
Code = r.Element("Area").Attribute("code").Value,
}).ToList();
}
您可以在一个查询中进行选择，然后在第二个查询中进行筛选，或者将它们合并到一个查询中：
两个查询：
// do te transformation
var employees =
from employee in xml.Descendants("CompanyInfo").Elements("Employee")
select new
{
EmployeeName = employee.Attribute("name").Value,
EmployeeDeptId = employee.Attribute("deptId").Value,
Regions = from region in employee.Elements("Region")
select new
{
Name = region.Attribute("name").Value,
AreaCode = region.Element("Area").Attribute("code").Value,
}
};
// now do the filtering
var filteredEmployees = from employee in employees
from region in employee.Regions
where region.AreaCode == "96"
select employee;
合并一个查询（相同的输出）：
var employees2 =
from selectedEmployee2 in
from employee in xml.Descendants("CompanyInfo").Elements("Employee")
select new
{
EmployeeName = employee.Attribute("name").Value,
EmployeeDeptId = employee.Attribute("deptId").Value,
Regions = from region in employee.Elements("Region")
select new
{
Name = region.Attribute("name").Value,
AreaCode = region.Element("Area").Attribute("code").Value,
}
}
from region in selectedEmployee2.Regions
where region.AreaCode == "96"
select selectedEmployee2;
但是有一件小事你应该考虑添加。为了健壮性，您需要检查元素和属性是否存在，然后选择将如下所示：
var employees =
from employee in xml.Descendants("CompanyInfo").Elements("Employee")
select new
{
EmployeeName = (employee.Attribute("name") != null) ? employee.Attribute("name").Value : string.Empty,
EmployeeDeptId = (employee.Attribute("deptId") != null) ? employee.Attribute("deptId").Value : string.Empty,
Regions = (employee.Elements("Region") != null)?
from region in employee.Elements("Region")
select new
{
Name = (region.Attribute("name")!= null) ? region.Attribute("name").Value : string.Empty,
AreaCode = (region.Element("Area") != null && region.Element("Area").Attribute("code") != null) ? region.Element("Area").Attribute("code").Value : string.Empty,
}
: null
};