.net - LINQ Query Returns List Of Empty Objects?

May 3, 2012

I have a query that 'selects' object of a type:

Dim l as IList(Of Foo) = (From dataRow As DataRow In table.Select()
Where CStr(dataRow("Column1")) = "A"
Select New Foo(CStr(dataRow("Column1")), _
CStr(dataRow("Column2")))).ToList()

What's happening is that if i set a break-point to the constructor of Foo and step, the constructor is hit and the parameters are loaded with the arguments. However, l has empty Foo objects (the members in every object are Nothing). What could be happening here?

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Linq To XML - Query Returns Nothing?

Jul 27, 2010

I have a XML file on which when I run a Linq query returns nothing in the for loop.

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.net - Linq Query Ignore Empty Parameters?

Apr 20, 2010

How do I get Linq to ignore any parameters that are empty? So Lastname, Firstname, etc? If I have data in all parameters it works fine...

refinedresult = From x In theresult _
Where x.<thelastname>.Value.TestPhoneElement(LastName) And _
x.<thefirstname>.Value.TestPhoneElement(FirstName) And _
x.<id>.Value.TestPhoneElement(Id) And _

[code]....

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C# - Linq To XML Query Creating Empty Items From XML

Feb 15, 2010

why is this xml

<?xml version="1.0" encoding="utf-8"?>
<items>
<item id="77" cityID="EE12345" cityDatum="15.2.2010. 11:28:35" />
</items>

[Code]....

If you, as some can't replicate these results, here's a screenshot:

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ASP.NET MVC - Linq Query With Count Returns Anonymous Type - How To Display In View

Sep 29, 2011

So I'm writing a query as follows:

Dim assSummary = From a In db.Assignments
Join ur In db.UserRegions
On a.Origin.ID Equals ur.Region.ID

[code]....

In the controller I can return the data easily as follows:

For Each c In assSummary
MsgBox(c.Description & " " & c.AssCount)
Next

If I pass the object through to the view using Viewdata("assSummary") = assSummary, how do I display the data? Every method I've tried results in messages about 'VB$AnonymousType_7(Of Integer,String) and I don't know how to retrieve the data from the anonymous type.

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.net - Detect Empty Results In A Linq-To-Entities Query?

May 29, 2009

The only way I know of is awkward:

'check for empty return
Dim count As Integer = (From s In myEntity.employee Where employeeID = myEmployeeIDVariable).Count
'If there is a record, then process

[code]....

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Using LINQ To Query XML And Return Empty String If No Data Is Present?

Mar 8, 2011

What I'm trying to do is to write a generic rss reader that I plug in any URL into without worry if the feed has all the common properties. For instance in my example below I'm looking for pubDate, however if no pubDate exists in the xml I'd like to return the current Date. I cannot seem to get the syntax right though.

Dim xmldoc As New XDocument
xmldoc = XDocument.Load(url)
Dim feeds = From feed In xmldoc.Descendants("item") Select New With { _

[code].....

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.net - Searching A List Of Objects In An Object List Using Linq?

Dec 22, 2010

I have 2 classes

Public Class Shipper
Public Property ShipperID As Long
Public Property CreateDate As DateTime

[Code].....

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Linq - Create A List Of Integers From A List Of Objects?

Nov 23, 2011

I'm trying to create a list of days(integer) from a list of dates(date).

I tryed to do this....

[Code]...

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Linq To Entities Query With Child Objects?

Oct 13, 2011

Basically I have the follwing:Dim ctx As New AdminCoreEntities Dim roles = (From r In ctx.Roles where r.Name.StartsWith("cust") Select r) 'list of System .Linq.IQueryable(Of AdminCoreModel.Role)

[code]...

The error i get when i run this is: Unable to cast object of type System.Data.Objects.ObjectQuery`1[AdminCoreModel.Role] to type AdminCoreModel.Role

Basically I have a many to many situation and I try to get all the Quicklinks objects queried by their roles and not quite sure why EF will cast to a single AdminCoreModel.Role when i.Roles is a collections of objects.

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LINQ To Objects, Query Arrays In Object?

Sep 15, 2011

I need to query an array. I have tried to use LINQ but with no success.

Here is a simplified structure of Insurance

Public Class Insurance
Public _typ As String
Public _numb As Number()

[Code]....

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Order By And Group By In A Linq To Objects Query?

Sep 28, 2010

How do I order by and group by in a Linq query?I tried..Dim iPerson = From lqPersons In objPersons Where Len(lqPersons.Person) > 0 Group lqPersons By key = lqPersons.Name Into Group Order By Group descending Select Group, key

For Each i In iPerson
tmp = tmp & vbNewLine & i.key & ", " & i.Group.Count
Next

[code].....

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VS 2010 Dynamically Building LINQ Query To Search Objects

Mar 24, 2011

I am creating a mediaplayer / playlist creator tool that basically imports MP3 songs into playlists (grids). I'm looking to add search functionality where the user can search all open playlists (or a subset of the open playlists). A Playlist is basically a collection of AudioFiles, where an AudioFile is a class that holds the filename of the MP3 file and then exposes the tags (Title, Artist, Album, etc) in public properties.

The idea is that the user can search for a certain expression (for example "the"), and that he can then choose whether to search in the title, in the title and artist, in the title or artist, in the title, artist and/or album, etc. However, I'm having a hard time implementing this and also having it kind of dynamic.

At the moment I am simply gathering all the AudioFiles from the open playlists (or from the subset of playlists the user chooses) and then running a simple LINQ query to find those AudioFiles where the Title contains the search text. Then I display the resulting AudioFiles in a new playlist window:

[Code]....

In case the AND / OR distinguishing is too hard, I would be happy to start with just letting it default to 'OR', so that the user can check Title and Album for example. If he would then search for 'a' then all songs that contain 'a' in their title as well as all songs that contain 'a' in their album should be returned. I guess that makes it easier, but I still wouldn't know how to dynamically create the LINQ query.

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LINQ Filtering List Objects?

Mar 1, 2011

I have list object and I need to check id in a comma separated string using LINQ in VB.NET, something like this:

dim strId as String = "1,2,3,5,"
dim myList = from objmylist where objmylist.id in (strId)

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List Of Objects Into SQL Query?

Oct 7, 2011

The scenario is this, I have several variables that are set as a list(of objects). The values for these lists are populated during code via a SQL query. I want to be able to take these values and then use them within another SQL query. Each time the program runs the values will be different and there will be more or less within the list.

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LINQ VB How To Check For Duplicates In A List Of Objects

Oct 11, 2011

I have a list of objects, each with 2 relevant properties: "ID" and "Name". Lets call the list "lstOutcomes".I need to check the list for duplicates (meaning object1.ID = object2.ID, etc.) and set a flag (valid = false, or something) if there is at least one duplicate. Also, it would be nice to send a message to the user mentioning the "Name" of the object, when it fails.I am sure I will need to use the Group By operator to do this, but I am not used to doing that in LINQ, and the examples out there are just not helping me. This article seems to be close to what i need, but not quite and it's in C#.

Here is a starting stab at it...
Dim duplist = _
(From o As objectType In lstOutcomes _

[code]......
help?

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.net - LINQ Sample: Select Typed Objects From A List

Jul 7, 2011

I have

Dim objectsList as List(Of Object) = GetAllObjects()
' Filter from Objects just Persons '
Dim peopleList as List(Of Person) = ???

What is the most efficient and effective LINQ expression to do it?

EDIT

1 Dim selectedObjects As List(Of Object) = GetAllObjects()

2 Dim selectedPeople As IEnumerable(Of Person)= selectedObjects.OfType(Of Person)

3 Dim people As List(Of Person) = selectedPeople.ToList()

Error on 3:

Value of type
'System.Collections.Generic.List(Of
System.Collections.Generic.IEnumerable(Of Person))' cannot be
converted to
'System.Collections.Generic.List(Of Person)'.

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Linq - Create A Concatenated String From A List Of Objects In 3.5?

Apr 27, 2012

I figure I should use 'Aggregate' but apparently I am getting it wrong First I get a list of my Entity objects Dim employers As List(Of myEntity) = (New XXXX()).getZZZ(userName, userType) Then I figured this would be a way to put all the names in a string Dim names as String = employers.Aggregate(Function(current, [next]) current.Name & " " & [next].Name)

[Code]....

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LINQ To Objects - GrandParent / Parent And Children List

Feb 3, 2010

Basically, I am trying to write a LINQ to Objects statement where the relationship is a grandparent, parent, child relationship. (You could also call it a Master Detail relationship.)

In Legacy code here is a simplified version what I am trying to accomplish.
Dim coverages As New List(Of Coverage)
Dim coverage As Coverage
For Each rl In oClaimsPolicy.RiskLocations
coverage = New Coverage
coverage.Level = "Location"
[Code] .....

If is it not clear one Location can have many Items and one Item can have many Coverages. I basically want to list the items and show the relationship between grandparent (Location), parent (Item) and child (Coverage).

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Using LINQ To Find Unique Values In A List Of Objects?

Jul 3, 2011

I am having so trouble with the ToUpper() procedure with strings. I am using LINQ to find unique values in a list of objects. In that whole process I set the values to compare to all lowercase in order to get a proper list. My goal is to populate a dropdown list with the values. I'm attempting to set the first letter of of the string to uppercase and keep the rest lowercase however the toUpper() procedure is not working?

Private Function FixCase(ByVal strIn) As String
Dim strOutput As String
Dim intStringLength As Integer = strIn.Length - 1
strOutput = strIn.Substring(0, 1)

[code].....

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Linq To Objects - (C#) Creating A Dictionary From An Existing List Without Looping?

Aug 31, 2011

I don't know if this is doable, maybe with Linq, but I have a List(Of MyType):

Public Class MyType
Property key As Char
Property description As String
End Class

And I want to create a Dictionary(Of Char, MyType) using the key field as the dictionary keys and the values in the List as the dictionary values, with something like:

New Dictionary(Of Char, MyType)(??)

Even if this is doable, internally it will loop through all the List items, I guess?

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.net - Linq Query To List?

Sep 2, 2011

Dim query = From o In myContainer.MyObjects Select o.MyStringProperty Distinct
Dim myProperties As List(Of String) = query.ToList????? 'no way!!!'
"query" type is IEnumerable(Of String)

I tried to use the query directly as a DataSource of a (infragistic) combobox, but it throws me NullReferenceException, so I decided to convert it to a listof strings, to be a more "classical" datasource.

Dim values As List(Of String) = query.AsQueryable().ToList()
does not work either: Value of type 'System.Collections.Generic.List(Of System.Linq.IQueryable(Of String))' cannot be converted to 'System.Collections.Generic.List(Of String)'.

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Copy Linq Query To List?

Sep 12, 2011

'Read RESX file and returns a List(Of ResXDataNode)[code]...

Provide two separate copies of the node? Or will the List and Linq query still be referencing the same data?

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LINQ Query For Deleting One Column From List(Of)

Jun 28, 2011

I have this code:

[Code]...

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Assign Result (from LINQ To XML Query) To List(Of String)?

Jul 6, 2011

Is it wrong? Please suggest me correct way.

Public Function ReadXML() As List(Of String)
Dim list As New List(Of String)
Dim xmlDoc As XDocument = XDocument.Load("C:\MappingFile.xml")

[code].....

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Linq Query To Compare If Collection Contains List Of String?

Feb 3, 2012

I am using a path comparison to find any children tags which works well when there is only 1 tag selected. This is my code for when multiples tags are selected but it is not working. Can you point me in the right direction?

Single Tag Selection (working)
Dim tagpath = uxTags.SelectedItem.Text
lnqCases = From i In lnqCases Where i.HelpDeskTagItems.Any(Function(x)

[code]...

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Linq To Xml Query Returning A List Of All Child Elements?

Mar 8, 2010

I have got an xml document which looks something like this.

<Root>
<Info>
</Info>
<Info>

[Code]...

How can i write a linqToXML query so that it returns me an IEnumerable containing each child element, in this case all five child elements of , so that i could iterate over them. The order of child elements is not definite, neither is number of times the may appear.

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VS 2008 Get Original List Index Of LINQ Query

Oct 24, 2010

If I use a LINQ query over some type of collection, is there any way to know the initial index of an element of the result?

Purpose: I make a query to set as source of a DataGridView, and on a (button)cellclick event I want to a call a method that needs to reference the collection at the correct index.

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Sql - When Run The Query In Query Analyzer, It Returns One Row But When Use The Same Query, No Rows Are Returned?

Aug 19, 2010

Here is the code:

Function getData(ByVal id As String)
Dim reader As SqlClient.SqlDataReader
Dim statement As String

[code].....

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.net - LINQ Query For Filter By Selected Items In Checkbox List?

Jun 30, 2011

Could not find this through Google or in SO questions.I have a checkbox listbox on my form. I want to filter my List by the list of selected Ids from that listbox that are checked, in SQL I would have done this like "Where TypeId In (1, 4, 5, 7)"... how do I do that in LINQ?

I feel like I am missing a really obvious answer, but cannot get it.

For argument sake... here is the what I have for sample data:

In Colors (List<of currentColors>)
ID, Name, TypeId
1, Red, 1
2, Blue, 1
3, Green, 2
4, Pink, 3

Selected Types 2 and 3 in CheckboxList: filteredColors

[Code]...

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