How can i fetch the 'Value' from the keyvalue pair using c#

Question

I would like to fetch the string mentioned in 'Value' for various parameter available under 'Name' using c#. Here is my current xml as follows:

<DrWatson>
  <Sets>
    <Set>
      <APIParameters>
        <Parameter Name="SID_STAGE" Value="101198" Required="true" />
        <Parameter Name="SID_QE" Value="Test 91817" Required="true" />
      </APIParameters>
    </Set>
  </Sets>
</DrWatson>

I would like to fetch the '101198' available under 'Value' for Name = SID_STAGE. Please suggest how can i perform it.

parse xml with linq http://stackoverflow.com/questions/670563/linq-to-read-xml it's really hard to find — Kamil Budziewski, Sep 17 '13 at 11:04
Please, next time provide some code you already have and describe problems you faced — Sergey Berezovskiy, Sep 17 '13 at 11:22
It's a perfectly valid question. I don't think there's any need to provide any code, anyone relatively new to C# .NET wouldn't really know what classes to use. I don't see any good reason why the user should be downvoted, particularly considering that they are clearly a new user. It's extremely off-putting to be downvoted so harshly on a first set of questions. — Ciaran Gallagher, Jan 06 '14 at 13:10

Sergey Berezovskiy · Accepted Answer · 2013-09-17T11:21:38.160

3

You can parse parameters dictionary (that is natural way to store key-value pairs) with LINQ to XML:

var xdoc = XDocument.Load(path_to_xml);
var parameters = xdoc.Descendants("Parameter")
                     .ToDictionary(p => (string)p.Attribute("Name"),
                                   p => (string)p.Attribute("Value"));

var stage = parameters["SID_STAGE"];

Keep in mind, that you should check if parameter exists in dictionary before getting it (if it is possible that parameter can not be in your xml):

if (parameters.ContainsKey("SID_STAGE"))
    // get parameter value

Also with XPath you can make query more concrete (if it is possible that somewhere will be another Parameter elements):

var xpath = "DrWatson/Sets/Set/APIParameters/Parameter";
var parameters = xdoc.XPathSelectElements(xpath)
                     .ToDictionary(p => (string)p.Attribute("Name"),
                                   p => (string)p.Attribute("Value"));

edited Sep 17 '13 at 11:21

answered Sep 17 '13 at 11:09

Sergey Berezovskiy

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nice approach with Dictionary, love it. Just afraid a bit of `ArgumentNullException` exception in cases when attribute Name is absent – Ilya Ivanov Sep 17 '13 at 11:15
@IlyaIvanov thanks, I assumed that parameter name is required (otherwise it makes no sense), but it simple solved with `Where(p => (string)p.Attribute("Name") != null)` filter :) – Sergey Berezovskiy Sep 17 '13 at 11:17
1

yes, sure. Just wanted to mention that. I had some negative experience, when I used `ToDictionary` on items, which key could be null. That wasn't quite obvious at that time) – Ilya Ivanov Sep 17 '13 at 11:18

Ilya Ivanov · Answer 2 · 2013-09-17T11:22:01.200

3

var result = XElement.Parse(xmlString)
                     .Descendants("Parameter")
                     .First(node => (string)node.Attribute("Name") == "SID_STAGE")
                     .Attribute("Value");

Console.WriteLine(result.Value); //prints 101198

Will throw an exception of element with this attribute is absent. Consider using FirstOrDefault if you would like another behaviour.

edited Sep 17 '13 at 11:22

answered Sep 17 '13 at 11:10

Ilya Ivanov

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For this sample xml it will work, but what if there is another element with attribute `Name` equal to SID_STAGE? :) – Sergey Berezovskiy Sep 17 '13 at 11:19
1

@lazyberezovsky fixed by adding `Parameter` node name. Note that XML allows to have several `Parameter` nodes with equal `Name` attributes ;) This will cause troubles with both of our solutions, mine won't throw exception thou, which could be quite bad sometimes – Ilya Ivanov Sep 17 '13 at 11:22
Few more lines, and we will handle that :) `GroupBy(p => (string)p.Attribute("Name")).Where(g => g.Key != null).Select(g => g.First()).ToDictionary(...)` – Sergey Berezovskiy Sep 17 '13 at 11:26

score 0 · Answer 3 · answered Sep 17 '13 at 11:12

0

Use a LINQ to XML query:

var xml = XDocument.Load("path...");
var foo = (from n in xml.Descendants("APIParameters")
           where n.Element("Parameter").Attribute("Name").Value == "SID_STAGE"
           select n.Element("Parameter").Attribute("Value").Value).FirstOrDefault();

Gives:

101198

answered Sep 17 '13 at 11:12

DGibbs

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I am getting an exception out there. – user2778482 Sep 17 '13 at 11:36
What exception is thrown and on what line? I've tested this and it works fine for me – DGibbs Sep 17 '13 at 11:39
Getting the following :Exception has been thrown by the target of an invocation. – user2778482 Sep 17 '13 at 11:42
I am getting this on Line 1 only – user2778482 Sep 17 '13 at 11:46
Which is this `var xml = XDocument.Load("path...");` - try not to just blindly copy and paste code. You need to set the filepath parameter of `XDocument.Load()`. The method takes a path to your XML or the XML string itself. Since I do not know the path to your XML, I have substituted this with `path...` purely as an example – DGibbs Sep 17 '13 at 11:47
var xml = XDocument.Load(FilePath_EXPRESS_API_SearchCriteria); i am using it this way only and i have verified and oberved that file path is valid – user2778482 Sep 17 '13 at 11:52
Doesn't look valid to me, the path should be enclosed in `""` for a start. Also, the path should lead to the file itself with the extension `.xml` which you don't have. – DGibbs Sep 17 '13 at 11:53

score 0 · Answer 4 · answered Jun 21 '17 at 17:10

using System;
using System.Xml.Linq;
using System.Web;
namespace YourProjectName
{
    public static class XmlFileRetrieve
    {
        public static string GetParameterValue(string name)
        {
            try
            {
                string path = HttpContext.Current.Server.MapPath("~/YourFolderName/YourXmlFileName.xml");
                XDocument doc = XDocument.Load(path);
                if (!(doc == null))
                {
                    var parameter = (from el in doc.Root.Elements("Parameter")
                                where (string)el.Attribute("Name") == name
                                select (string)el.Attribute("value")).Select(keyvalue => new { name = keyvalue }).Single(); ;
                    return parameter.name;
                }
                return "";
            }
            catch (Exception e)
            {string error=e.Message;return "";
            }
        }
    }
}

It should get the value; supply name as SID_STAGE – M. Bhavani Jun 21 '17 at 17:11 — M. Bhavani, Jun 21 '17 at 17:11

How can i fetch the 'Value' from the keyvalue pair using c#

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