.Net LINQ Query To Determine Whether More Than One Element Has The Same Value For A Property?

Jun 28, 2011

I am trying to write a LINQ query which will return true if there are multiple objects which have a property with the same value.

Here is what I have come up with so far:

Formatters.Where(Function(f As DataModel.Formatter) _
Formatters.Select(Function(f2 As DataModel.Formatter) f2.Name.ToLower()).Contains(f.Name.ToLower())).Count > 1

However the above always returns true as long as their are more then 1 elements in the list?

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Determine The Type Of Object To Use To Store A Linq Query?

Jul 3, 2010

I am using VB .Net for this, so I don't have access to var or this would be a simple matter.Right now my query is as follows

[code]...

So I used this query in LinqPad to help me determine what the object would look like. I got back a IOrderQueryable(Of RSError) which then contained a IGrouping(Of String, RSError) for each grouped collection of objects returned by the query.However I ended up with the current object type of errors as IOrderedQueryable(Of IGrouping(Of String, RSError)) because of the cast error I am getting in VS.

[code]...

I'm not sure how to get rid of the VB$AnonymousType_1 Part of the returned object.Am I even on the right track here or am I missing something completely?

LINQ Query - Property Password Is ReadOnly

Dec 4, 2010

I am trying to create the functionality of resetting the password for the program. However, when I try to create the code for this feature, I am getting "Property 'Password' is 'ReadOnly'". How would I go about getting around this.

Dim strUsername As String = txtNewUsername.Text
Dim strNewPassword As String = txtNewPassword.Text
Dim strOldPassword As String = txtOldPassword.Text
txtNewUsername.Text = strUsername
txtNewPassword.Text = strNewPassword
txtOldPassword.Text = strOldPassword
[Code] .....

How To Use The Vb Equivalent Of ++ For An Index Property In A Linq Query Projecting A New Type

May 3, 2011

I'd normally do this in C# but since I've got to get this code in this particular assembly which is a vb.net one, I'm stuck.

Here's my linq query:

Dim i As Integer = 0

Dim oldAndCurrentIntersectionOnNames = From currentApplicant In currentApplicants _
Group Join oldApplicant In oldApplicants _

[CODE]...

You'll see the .Index = i+=1

This was my attempt to do what I'd quite happily do in C# (i.e. Index = i++) in VB. Unfortunately the VB compiler doesn't like that. how I'd do this in VB.

LINQ Query Is Enumerated - Turn On Some Kind Of Flag That Alerts Me Each Time A LINQ Query Is Enumerated?

Sep 22, 2009

I know that LINQ queries are deferred and only executed when the query is enumerated, but I'm having trouble figuring out exactly when that happens.Certainly in a For Each loop, the query would be enumerated.What's the rule of thumb to follow? I don't want to accidentally enumerate over my query twice if it's a huge result.

For example, does System.Linq.Enumerable.First enumerate over the whole query? I ask for performance reasons. I want to pass a LINQ result set to an ASP.NET MVC view, and I also want to pass the First element separately. Enumerating over the results twice would be painful.It would be great to turn on some kind of flag that alerts me each time a LINQ query is enumerated. That way I could catch scenarios when I accidentally enumerate twice.

Determine If Structure Element Is Numeric?

Jan 20, 2011

I'm writing a rather complex VB2008 programme, To simplify the things, here is the code:

Structure strucFirst
Dim Field1 as Integer
Dim Field2 as Single

[Code]....

I'm not sure if the pseudocode above is possible in VB at all?

Determine What Element Of A Form Is The One Responsible For An Autopostback In ASP.NET?

Nov 12, 2009

I have a number of dropdown lists that I'm trying to chain together and they all have autopostback. How can I tell which one of the dropdown lists was the one responsibe for the autopostback?

Link To XML - Determine If An Element Exists In A List?

Apr 27, 2012

I am working with LINQ to XML in VB (although answers in C# are great, too). First off- my code works, so this is not critical. However, I can't help but think that what I'm doing with conditional logic should already be doable using the LINQ query itself. Here's what I've got:

'Get the Description elements in the ResultData section where the value is "Op Code"
Dim opCodes As List(Of XElement) = (From c In xdoc.Descendants("ResultData").Descendants("Description")
Where c.Value = "Op Code"[code].....

Please don't be too critical of my method of locating the sibling nodes- the XML files are produced by a third-party testing device and this is the only generic way to get the values I need. What I'm really looking for here is a better way to handle the If block.

VS 2008 Determine If Element On Webpage Exists?

May 9, 2009

Just like the title says, I have a webbrowser and I need to determine if the element exists or not before I invoke it.

Using LINQ To Return Element In Collection, Would Like To Return Nothing If Element Not Found?

Mar 3, 2011

I would like the following function to return Nothing if the element with the specified key is not in the collection. Instead, it returns an error - something to the effect of "no element found"

Public Class MyCollection
Inherits System.Collections.ObjectModel.Collection(Of MyType)
Public Function FindByActivityKey(ByVal searchValue As Integer) As MyType

[code]....

Linq To Xml Get Certain Element Value?

Apr 14, 2011

The XML sample below has two records and each record has three similar Nodes (<datafield tag="500" >) What I want to accomplish is get the value of the second Node <datafield tag = "5000">. The fallowing code I gets the value for all three nodes but I want something like get elementat(1). I tried this but it didn't worked MsgBox(xEle.Elements.ElementAt(1).Value)

Code:

Dim xd As XDocument = XDocument.Load("C:UsersstopeteDesktopMarc_convertxml.xml")
If xd IsNot Nothing Then
Dim datafields = From datafield In xd.Descendants("datafield")

[code]....

.net - ActiveRecord Linq/NHibernate Linq Not Building Query Completely?

Jul 14, 2011

given this function:

Public Function Search(ByVal StartIndex As Integer, _
ByVal MaxResults As Integer, _
ByVal AccountNumber As String, _
ByVal LastName As String, _

[Code]....

instead of what I expected:

Select count(*) from remitline where lastname = "smith"

What am I doing wrong building up the where clause? I'm using Castle ActiveRecord 2.1

Performance Gain In LINQ Query Vs LINQ Stored Procedure?

Aug 6, 2009

if there is that much of a performance gain in running a LINQ stored procedure versus a LINQ query?

Add An Element To The XML Document With LINQ To XML?

Mar 15, 2010

I'm adding an element to existing XML doc with the following code:

Dim theXMLSource As String = Server.MapPath("~/Demo/") & "LabDemo.xml"
Dim nodeElement As XElement
Dim attrAndValue As XElement = _

[code]....

It makes error like this:

System.NullReferenceException: Object reference not set to an instance of an object.Object reference not set to an instance of an object.Error line: nodeElement.Add(New XElement(attrAndValue))

Get The Value Of An XML Element Using Linq Even When Empty?

May 13, 2010

Please excuse my stupidity, I tend to find the traversing XML overly complicated.

[Code]...

Once it gets to staffBio I get an error saying "Object reference not set to an instance of an object." obviously because that node does not exist. My question is how can I assign the value to a variable even when it is empty without having to do a conditional check before each assignment?

How To Update XML Element With LINQ

Mar 15, 2010

I'm editing XML element with the following XML:
<?xml version="1.0" encoding="utf-8"?>

<LabSerivceInfo><LabService>
<ServiceType>Copy</ServiceType>
<Price>1</Price></LabService>
[Code] .....
How to update the ServiceType and Price where ServiceType = varServiceType?

Increment Element Using LINQ To XML?

Nov 12, 2009

Using VB.NET (3.5), i have an ArrayList of Employees. I'm trying to build an XML representation (to feed another system) and one of the fields is a simple incrementing ID, starting at 1.[code]...

Linq To XML: Writing Xsi Into An Element?

Feb 25, 2011

Just playing about with LinqToXml and I need to form a xelement as follows:

Dim xe As XElement = _
<Xml>
<ElementOne>
<SubElement></SubElement>
<SubElement></SubElement>

[Code]...

This creates an error here: xsi:type "XML namespace prefix 'xsi' is not defined"

Is it possible to write this in Linq to xml?

LINQ XML Get Parent Element

Oct 28, 2010

Using the XML elements below, I am trying to locate all table elements where they have a column@Name equal to a specific item such as "email" and return the Database@Location and Table@Name. My LINQ statement returns the proper table@name but for each element found returns the first database@Location for both. So my question is, how can I search for a column@Name and return the proper Database@Location and Table@Name [Code]

Update XML Element With LINQ To XML?

Mar 15, 2010

I'm trying to update an element in the XML document below:

Here's the code:

Dim xmldoc As XDocument = XDocument.Load(theXMLSource1)
Dim ql As XElement = (From ls In xmldoc.Elements("LabService") _
Where CType(ls.Element("ServiceType"), String).Equals("Scan") _

[code]....

But, I got this error message:

Object reference not set to an instance of an object.Exception Details: System.NullReferenceException: Object reference not set to an instance of an object.Error line:ql.SetValue("23")

Asp.net - Complex Linq Query - Add A .Where() Or .Any() Predicate To Reduce Query Complexity (in VB)?

Sep 14, 2010

I have to join two main tables, and I need to filter the results by elements in an ASP.NET web form. These filters are created on the fly so I have to use a lot of where extensions to filter the query. I want to execute the query with as optimized SQL as possible.

I am first doing a simple join between TW_Sites and TW_Investigators. Then there are two sub-tables that are involved. TW_InvestigatorToArea and TW_InvestigatorToDisease. While most of the where clauses are working fine, I have found a performance issue that won't be an issue right now, but will be an issue as the table gets bigger.

The arrays DiseaseCategories and DiseaseAreas would be the results of a CheckBoxList result.

Protected Sub LoadResults()
'Get Dictionary of Filters
Dim FilterDictionary As OrderedDictionary = Session.Item("InvestigatorFilterDictionary")
' Initialize LinqToSql

[code]....

LINQ To XML Syntax For XML Element With Attributes?

May 13, 2009

I'm a bit of a LINQ newbie and I was having some trouble with the following. I'm trying to perform a query using LINQ on an XML file and store the results in a list of DataClass objects that match the XML.I've got an XML file that is defined like this:

<NewDataSet>
<NewDataTable>
<Field>Accepted ASNs</Field>
<Val>59</Val>[code]....

I have created a Data class to support this XML format. What I would like to do is create a LINQ Query to grab these 3 records and store them into a List of my DataClass. In order to support multiple Order elements, I have my class defined with a generic list of "Order" structs... It looks like this:

Public Class ASNData
Private _field As String
Private _value As String[code].....

how to grab the 3 order elements and store them into my list of Order structs.

Linq To Xml Output Valaue From A Certain Element?

Apr 15, 2011

It has two records and each record has three similar Nodes (<datafield tag="500">). What I want to accomplish is get the value of the second Node <datafield tag = "5000">. The following code I gets the value for all three nodes but I want something like get elementat(1).I tried this but it didn't worked.

MsgBox(xEle.Elements.ElementAt(1).Value)
Dim xd As XDocument = XDocument.Load("C:UsersstopeteDesktopMarc_conv ertxml.xml")
If xd IsNot Nothing Then
Dim datafields = From datafield In xd.Descendants("datafield")
Where (datafield.Attribute("tag").Value = "500")

[Code]...

Linq To XML Remove Element Where Value Is Null?

Apr 19, 2011

I have a XML xElement like[code]...

In order to get rid of Trick nodes where value is null, I wrote:

myXmlElement.<Play>.<Trick>.Where(Function(m) m.<Trick>.Value = "").Remove()

LINQ Query Using The Dynamic LINQ Library?

Mar 31, 2011

Forgive my ignorance on this.I have this LINQ Query:Dim ngBikersDataContext As New CarBikeWalkDataContext

bikersList = (From c In ngBikersDataContext.Reg_Bikers _
Order By c.L_Name _
Select New Bikers() With { _
.BikerID = c.BikerID, _
.F_Name = c.F_Name, _

[Code]...

with the error "Overload resolution failed because no accesible 'Select' accepts this number of arguments."
Over the "NEW" I get an error " ')'expected."

C# - Linq - Find Element In Nested Collections

Feb 19, 2011

I have a generic list - SupportedTypeGroups. Each SupportedTypeGroup has SupportedTypes property (generic list of SupportedType). How to construct a Linq query to locate SupportedType with required name?

LINQ - Order By Anonymous Type (Value Element)

Jan 5, 2012

I am using linq to fill a gridview with the information from an xml from code behind. I would like to order my Grid according to one of my elements in the xml ("value element").

gvResourceEditor.DataSource = (From resElem In resourceElements.Elements("data") _
Select New With { _
.Key = resElem.Attribute("name").Value, _
.Value = HttpUtility.HtmlEncode(resElem.Element("value").Value), _
.Comment = If(resElem.Element("comment") IsNot Nothing, HttpUtility.HtmlEncode(resElem.Element("comment").Value), String.Empty) _
}).OrderBy(?????)

Reading XML Element & Child Nodes Using LINQ

Aug 26, 2009

I am new in LINQ world.I need an urgent help in reading the xml elements using LINQ with specific where condition.I need to find the max air_temp for a county i.e where county name = "Boone" and hour id = "06/03/2009 09:00CDT".[code]

IDE :: Binding Via Property Element Syntax?

Dec 20, 2009

First, I am making the assumption that anything you can do in "Attribute Syntax" (AS), you can do in "Property Element Syntax" (PES), but not vice-versa. That is the reason I intend on coding completely in PES if possible. I have encountered quirks though.The first issue is regarding AS "x:Name" or PES "<FrameworkElement.Name>": If I use PES, I must make sure it is the last element, otherwise any PES below it will error on build; eg "Value of type 'System.Windows.ResourceDictionary' cannot be converted to 'Namespace.ClassName'."

A problem encountered intermixing AS and PES: Set "x:Name" and "MinWidth" as AS. Set "Title" as PES.

[Code]...

Using LINQ To XML With Global Namespace - Xmlns Is Added To Each Non-data Element?

Jan 14, 2010

I have to create an xml doc for a vendor who specifically states they must have their xml as follows:

<?xml version="1.0" encoding="utf-16" standalone="yes"?>
<WMWROOT xmlns="http://www.blahblah.com/BLAH/Interface">
<WMWDATA>[code].......

I cannot find a way to get LINQ to spit out xml the way they want. Question is, can LINQ do it or do I need to resort to hardcoding the xml the old way before LINQ to XML?

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