[英]Dynamic select with linq-to-xml?
我得到了一个XML文档,其中包含大量数据,这些数据分为category-> subcategory。 像这样:
<?xml version="1.0" encoding="utf-8" ?>
<data>
<car>
<transmission>
<option value="1" text="Manual" />
<option value="2" text="Automatic" />
</transmission>
<milage>
<option value="2" text="0-499" />
<option value="4" text="500-999" />
<option value="6" text="1000-1499" />
<option value="8" text="1500-1999" />
<option value="10" text="2000-2499" />
</milage>
<fuel>
<option value="1" text="Gasolin" />
<option value="2" text="Diesel" />
<option value="3" text="E95" />
<option value="4" text="Hybrid" />
<option value="5" text="Electric" />
</fuel>
</car>
</data>
我正在使用Ajax从xml文档中检索所需的数据。 像这样:
public string GetData(int typeOfData)
{
List<string> queryString = new List<string>();
switch (typeOfData)
{
case 1:
// Car->Milage
queryString.Add("car");
queryString.Add("milage");
break;
case 2:
// Car-Fuel
queryString.Add("car");
queryString.Add("fuel");
break;
}
// Now i need to construct a query to return the data, i have tried something like this:
var results = from data in db.Elements("data") where (queryString => db.Elements(test)) select new { ID = data.Attribute("value").Value, Name = data.Attribute("text").Value };
}
}
使用XPath,我可以简单地创建一个查询字符串,但是如何在linq中做到这一点呢?
您可以在Linq中使用XPath。
public string GetData(int typeOfData)
{
string query = null;
switch (typeOfData) {
case 1:
query = "/data/car/milafe/option";
break;
case 2:
query = "/data/car/fuel/option";
break;
}
var results = from e in db.XPathSelectElements(query)
select new { ID = e.Attribute("value").Value, Name = e.Attribute("text").Value };
}
您需要遍历XML树并获取包含switch
语句中的选项的元素,如下所示:
public string GetData(int typeOfData)
{
XElement container;
switch (typeOfData)
{
case 1:
// Car->Milage
container = db.Root.Element("car").Element("mileage");
break;
case 2:
// Car-Fuel
container = db.Root.Element("car").Element("fuel");
break;
default:
throw new ArugmentOutOfRangeException("typeOfData");
}
var results = container.Elements("option")
.Select(data => new { ID = data.Attribute("value").Value, Name = data.Attribute("text").Value };
}
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