I have an XElement which I am getting after parsing an xml. This XElement needs to be read only when the need arises so, I have stored it in a list for future use.
I have to read this XElement using Linq.
XDocument doc = XDocument.Parse(DataManager.offeringElements[index].DataElem.ToString());
var docNode = from dataNode in doc.Descendants("DataLinks")
select new
{
Offering = dataNode .Element("link").Value,
linkUrl = dataNode.Element("link").Attribue("href").Value
};
the Xelement has the following nodes
<DataLinks>
<link href="">a. Management</link>
<link href="">b. Analytics</link>
<link href="">c. Development</link>
</DataLinks>
My problem is that I am not able to read all the three nodes.I am able to get only the first node. Where is it going wrong?
This should work i.e. Elemenets not Descendants and ensure when selecting new, you are selecting a type of object.
public class ObjectType
{
public Offering {get; set;}
public linkUrl {get; set;}
}
var docNode = from dataNode in doc.Elemenets ("DataLinks")
select new ObjectType
{
Offering = dataNode .Element("link").Value,
linkUrl = dataNode.Element("link").Attribue("href").Value
};
I would do it like this. IMHO, the method syntax looks cleaner then the query syntax. Note that this is untested code.
IEnumerable<XElement> seqLinks = doc.Descendants("DataLinks").Single()
.Descendants("link");
foreach(XElement link in seqLinks)
{
Console.WriteLine("Value is {0}, and href is {1}",
link.Value, link.Attribute("href").Value)
}
Related
Trying to create a prayer time app for prayertimes in Oslo. I have a XML file located in the app.
What i want to do:
Based on month and the day, get value for morning prayer, evening prayer and so on.
I want one value at a time, and show it in a textblock. how do i do it?
I am currently getting the info in a listBox but i rather want the single value to be shown in a textblock. Or should i use some other thing?
public class PrayerTime
{
public string Fajr { get; set; }
public string Sunrise { get; set; }
}
To get the value:
XDocument loadedCustomData = XDocument.Load("WimPrayerTime.xml");
var filteredData = from c in loadedCustomData.Descendants("PrayerTime")
where c.Attribute("Day").Value == myDay.Day.ToString()
&& c.Attribute("Moth").Value == myDay.Month.ToString()
select new PrayerTime()
{
Fajr = c.Attribute("Fajr").Value,
Soloppgang = c.Attribute("Soloppgang").Value,
};
listBox1.ItemsSource = filteredData;
Also i want to know how best the XML should be set up for this purpose.
Like this:
<PrayerTime>
<Day>1</Day>
<Month>5</Month>
<Fajr>07:00</Fajr>
<Sunrise>09:00</Sunrise>
</PrayerTime>
Or like this:
<PrayerTime
Day ="1"
Month="5"
Fajr="07:00"
Sunrise="09:00"
/>
yourTextBox.Text = filteredData.First().Fajr;
As to know whether it's best to put information in a XML file as attributes or nodes, that's a recurrent question with no definite answer. In most cases, it's just a matter of taste.
I am trying to work with MvcContrib Grid control. But I cannot seem to get the sorting to work on complex objects that hold other objects.
I have setup my controller/classes/Views similar to the OP in this question.
Sorting with MVCContrib
I have tried to use the SortColumnName to my childobject.property but it gives me an error saying My main object does not have this property. This is my code snippet
//POCO class
class Issue {
public int ID {get; get; }
.....
public int priorityId {get; set;}
public virtual Priority priority {get; set;}
}
//Controller code
public ViewResult Index(int? pageNo, GridSortOptions sort)
{
var issues = db.issues.Include(i => i.priority);
ViewBag.sort = sort;
if (!string.IsNullOrEmpty(sort.Column))
{
issues = issues.OrderBy(sort.Column, sort.Direction);
}
return View(issues.ToList().AsPagination(pageNo ?? 1, 10));
}
//View code for the Grid
#Html.Grid(Model).Sort(ViewBag.sort as GridSortOptions).Columns(column => {
column.For(issue => Html.ActionLink(" ", "Edit", new { id = issue.ID, areas = "Issues", controller = "Main"}, new { #id="editBtn"})).Named("Edit");
column.For(issue => Html.ActionLink(issue.ID.ToString(), "Edit", new {id = issue.ID, areas = "Issues", controller = "Main"})).Named("ID").Sortable(true);
column.For(issue => issue.priority.codeDesc).Named("Priority").SortColumnName("priority.codeDesc").Sortable(true);
}).Empty("No data found")
When I try to sort on the priority string, it gives me an error saying 'priority.codeDesc is not a property of Issue'.
TIA
The issue here isn't actually related to the grid, but rather to the .OrderBy extension method provided as part of the MvcContrib sorting extensions. This extension is fairly simplistic and I only wrote it to cover simple cases where you want to sort on a direct property of the object, however in your case you're trying to order on a nested property ("priority.codeDesc") which isn't supported - you can't use dot notation with this extension.
You'd either need to switch to using a different mechanism to perform the actual sorting, or if this is a one-off situation then you could hard-code the sorting logic for this particular column (not ideal, but if it's a one off then it's simpler than writing a new sorting mechanism), eg:
if (!string.IsNullOrEmpty(sort.Column))
{
if(sort.Column == "priority.codeDesc")
{
issues = issues.OrderBy(x => x.priority.codeDesc);
}
else
{
issues = issues.OrderBy(sort.Column, sort.Direction);
}
}
OMG! Dots!
I was in the same boat but thanks God I found a brilliant solution posted by our fellow developer Jarrett Meyer. I found it after maybe 3 hours Googling in the past and just now when I decided to boost my pagination and sorting with MvcContrib Grid.
You can find the full post here:
Server-Side Sorting With Dynamic LINQ
His code saved me... :D The use of LINQ's Aggregate function was AWESOME! Kudozzz to him.
I had to change Jarretts' original code a little bit to fit it to my needs. Here's the code after I modified it:
public static IQueryable<T> OrderBy<T>(this IQueryable<T> collection, GridSortOptions sortOptions)
{
if (string.IsNullOrEmpty(sortOptions.Column))
{
return collection;
}
Type collectionType = typeof(T);
ParameterExpression parameterExpression = Expression.Parameter(collectionType, "p");
Expression seedExpression = parameterExpression;
Expression aggregateExpression = sortOptions.Column.Split('.').Aggregate(seedExpression, Expression.Property);
MemberExpression memberExpression = aggregateExpression as MemberExpression;
if (memberExpression == null)
{
throw new NullReferenceException(string.Format("Unable to cast Member Expression for given path: {0}.", sortOptions.Column));
}
LambdaExpression orderByExp = Expression.Lambda(memberExpression, parameterExpression);
const string orderBy = "OrderBy";
const string orderByDesc = "OrderByDescending";
Type childPropertyType = ((PropertyInfo)(memberExpression.Member)).PropertyType;
string methodToInvoke = sortOptions.Direction == MvcContrib.Sorting.SortDirection.Ascending ? orderBy : orderByDesc;
var orderByCall = Expression.Call(typeof(Queryable), methodToInvoke, new[] { collectionType, childPropertyType }, collection.Expression, Expression.Quote(orderByExp));
return collection.Provider.CreateQuery<T>(orderByCall);
}
Now you can call this extension method like this in your controller method:
var users = Database.Memberships.OrderBy(sort);
where sort is GridSortOptions that lives in MvcContrib.UI.Grid.
sort.ColumnName can contain strings like these ones now:
User.UserName
User.MyRelatedEntity.RelatedEntityProperty
User.MyRelatedEntity.RelatedEntityProperty.AndSoON
Note that when you create your Grid columns you can specify
.SortColumnName("User.UserName")
I have a linq query to a XML dataset, which when executed is generating a NullReferenceException.
XDocument dataDoc = XDocument.Load(new StringReader(e.Result));
var Genres = from genre in dataDoc.Descendants("genres")
where (!genre.Element("ID").IsEmpty)
select (string)genre.Element("id").Value + ',' + (string)genre.Attribute("name").Value + ',' + (string)genre.Attribute("url").Value;
foreach (string myGenre in Genres)
{
}
When executed, the Linq query works fine, but when the code attempts to iterate through the foreach loop, the NullReferenceException occurs.
Now, i think that the issue has to do with the XML data I am reading, which looks like the following:
<genres>
<translated>true</translated>
<genre name="1">
<id>28</id>
<url>http://url1</url>
</genre>
<genre name="2">
<id>12</id>
<url>http://url2</url>
</genre>
</genres>
Is the first child node, which is different in structure, causing the issue?
My class behind this shouldn't be an issue, but is the following (just in case):
public class Genre
{
public string ID { get; set; }
public string Name { get; set; }
public string URL { get; set; }
}
genre.Attribute("url") returns null, since there is no url attribute.
You need to call Element, not Attribute.
EDIT: Calling dataDoc.Descendants("genres") returns the single <genres> element, which is not what you want.
You need to call Descendants("genre") (singular) to get the individual <genre ...> elements.
You could also call dataDoc.Descendants("genres").Elements to get the elements inside the <genres> element.
SLaks has pointed out the mistake in using Attribute rather than Element, but there's another improvement you can make in your code. Currently you're using the Value property and then redundantly casting to string. If you just cast an XAttribute or XElement to string, then if the original reference is null, the result will be null as well, rather than an exception being thrown. There's no point in using Value and casting.
I have an XML file like this:
<SiteConfig>
<Sites>
<Site Identifier="a" />
<Site Identifier="b" />
<Site Identifier="c" />
</Sites>
</SiteConfig>
The file is user-editable, so I want to provide reasonable error message in case I can't properly parse it. I could probably write a .xsd for it, but that seems kind of overkill for a simple file.
So anyway, when querying for the list of <Site> nodes, there's a couple of ways I could do it:
var doc = XDocument.Load(...);
var siteNodes = from siteNode in
doc.Element("SiteConfig").Element("Sites").Elements("Site")
select siteNode;
But the problem with this is that if the user has not included the <SiteUrls> node (say) it'll just throw a NullReferenceException which doesn't really say much to the user about what actually went wrong.
Another possibility is just to use Elements() everywhere instead of Element(), but that doesn't always work out when coupled with calls to Attribute(), for example, in the following situation:
var siteNodes = from siteNode in
doc.Elements("SiteConfig")
.Elements("Sites")
.Elements("Site")
where siteNode.Attribute("Identifier").Value == "a"
select siteNode;
(That is, there's no equivalent to Attributes("xxx").Value)
Is there something built-in to the framework to handle this situation a little better? What I would prefer is a version of Element() (and of Attribute() while we're at it) that throws a descriptive exception (e.g. "Looking for element <xyz> under <abc> but no such element was found") instead of returning null.
I could write my own version of Element() and Attribute() but it just seems to me like this is such a common scenario that I must be missing something...
You could implement your desired functionality as an extension method:
public static class XElementExtension
{
public static XElement ElementOrThrow(this XElement container, XName name)
{
XElement result = container.Element(name);
if (result == null)
{
throw new InvalidDataException(string.Format(
"{0} does not contain an element {1}",
container.Name,
name));
}
return result;
}
}
You would need something similar for XDocument. Then use it like this:
var siteNodes = from siteNode in
doc.ElementOrThrow("SiteConfig")
.ElementOrThrow("SiteUrls")
.Elements("Sites")
select siteNode;
Then you will get an exception like this:
SiteConfig does not contain an element SiteUrls
You could use XPathSelectElements
using System;
using System.Linq;
using System.Xml.Linq;
using System.Xml.XPath;
class Program
{
static void Main()
{
var ids = from site in XDocument.Load("test.xml")
.XPathSelectElements("//SiteConfig/Sites/Site")
let id = site.Attribute("Identifier")
where id != null
select id;
foreach (var item in ids)
{
Console.WriteLine(item.Value);
}
}
}
Another thing that comes to mind is to define an XSD schema and validate your XML file against this schema. This will generate meaningful error messages and if the file is valid you can parse it without problems.
hi i have an xml like this
<?xml version="1.0"?>
<DataSetExchangeWMS xmlns="http://tempuri.org/DataSetExchangeWMS.xsd">
<dtObjektInfo>
<LanguageCode>1031</LanguageCode>
<LiegenschaftID>7463</LiegenschaftID>
</dtObjektInfo>
1040
7463
09
Now as i learned from tutorial i get my xml file and select node from descendant.
now why the first foreache does not work? i need to create complicated queries.
XDocument test = XDocument.Load(Server.MapPath("~/XML/objects.xml"));
var objecte = from i in test.Root.Descendants("dtObjektInfo")
select i;
// new test with where
var objecte = from i in test.Descendants( ns + "dtObjektInfo")
where i.Element("LanguageCode").Value == "1031"
select i;
foreach (var item1 in objecte)
{
Response.Write(item1.Value);
}
foreach (XElement item in test.Root.Nodes())
{
Response.Write(item.Value + "<br />");
}
You're not using the XML namespace defined in your XML document!
You need to specify the XML namespace when you query your XML:
XNamespace ns = "http://tempuri.org/DataSetExchangeWMS.xsd";
var objecte = from i in test.Root.Descendants(ns + "dtObjektInfo")
select i;
Marc
Marc has basically sorted your issues out, but i thought i'd throw in some consideration.
If you have complicated XML, i would suggest using defined objects. it makes things easier in the long run.
for your example
public class dtObjektInfo
{
public string LanguageCode { get; set; }
public string LiegenschaftID { get; set; }
}
and then your code to call it would turn into
XDocument root = XDocument.Load("c:\\test.xml");
XNamespace ns = "http://tempuri.org/DataSetExchangeWMS.xsd";
dtObjektInfo objecte = (from i in root.Descendants(ns + "dtObjektInfo")
select new dtObjektInfo
{
LanguageCode = i.Element(ns+"LanguageCode").Value,
LiegenschaftID = i.Element(ns+"LiegenschaftID").Value
}).First();
Then you can access the values directly from your dtObjektInfo object. makes coding a lot easier with large xml files as all the work is done in the linq query and then you have a final object.
The benefits of this is that you only have to get the linq right once. coding will be aided by the fact that you are now working with an object whose properties are known (AND INTELLISENSE YAY). all the elements can be cast to the correct types (or exceptions thrown). saving a lot of issues later.