Linq to XML文件查询不起作用

Question

This is my XML file and I am using linq and entity framework

<?xml version="1.0" encoding="utf-8" ?>
<Projects>
  <Project ProjectId="JP001" Country="Canada" ProposedBy="Jim Priac"/>
  <Project ProjectId="KS12" Country="Canada" ProposedBy="Aya Suriour"/>
  <Project ProjectId="ANS16" Country="Malesia" ProposedBy="Gour martin"/>
 <Projects> 

the linq query I am using is

   IEnumerable<string> Proposed_By = from project in xmldoc.Descendants("Projects").Elements("Project")
                                            where project.Attribute("Country") == "Canada"
                                             select project.Attribute("ProposedBy");

but I am not getting correct output

Answer 1

You need to compare to the value of the attribute and not to the attribute itself.

IEnumerable<string> Proposed_By = 
        from project in xmldoc.Descendants("Projects").Elements("Project")
        where project.Attribute("Country").Value == "Canada"
        select project.Attribute("ProposedBy").Value;

I would however go a step further and also check if the attribute is there (since calling the Value property on a null object would result in an exception:

IEnumerable<string> Proposed_By = 
        from project in xmldoc.Descendants("Projects").Elements("Project")
        where project.Attribute("Country") != null 
              & project.Attribute("Country").Value == "Canada"
              & project.Attribute("ProposedBy") != null
        select project.Attribute("ProposedBy").Value;

Answer 2

First see if your file is getting make corrections to your linq query

XDocument xmldoc = XDocument.Load(Path.GetFullPath("filename"));
    IEnumerable<string> Proposed_By = from project in xmldoc.Descendants("Projects").Elements("Project")
                                    where project.Attribute("Country").Value == "Canada"
                                     select project.Attribute("ProposedBy").Value;

Answer 3

将.Value与属性名称一起使用

Answer 4

Another Way: It returns NULL if Value is not present.

 var Propposed_By = from project in xd.Descendants("Projects").Elements("Project")
                           where project.Attribute("Country").Value == "Canada"
                           select (string)project.Attribute("ProposedBy");