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.
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.
I am trying to get an index of a List(Of Details) Details being a class i use instead of an annon method. Is it because i am using array.findindex when it's not an array but a list(Of???
Dim index As Integer = Array.FindIndex(Details, Details.FirstOrDefault(Function(nd) nd.Name = "name"))
Error1Data type(s) of the type parameter(s) in method 'Public Shared Function FindIndex(Of T)(array() As T, match As System.Predicate(Of T)) As Integer' cannot be inferred from these arguments. Specifying the data type(s) explicitly might correct this error.
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)'.
'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?
I have this code:
[Code]...
Is that possible to get current Enumerator (...or iterator? Don't know which tern is the correct one) in a LINQ query ? For example, I try to create a XML output (via LINQ to XML) of all currently loaded assemblies. [code] is it possible to somehow get current "index" (counter?) from LINQ's Selects? I would like to use it in XML. [code]
View 1 RepliesI 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?
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].....
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]...
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.
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]...
GOAL: Bind nested ListViews to LINQ generated iQueryable of anonymous type. I want to use LINQ because you can use GroupBy and bind the nested ListView to the 'it' keyword.
SETUP: I have groups of sets of conditions. Each set of conditions is stored in the BillingCodes table. Each group of BillingCodes is stored in the BillingGroups table.
I have a custom object that stores the ID, Name, and NumCodes for each BillingGroup that the user has chosen.I have a collection of these objects called GroupsList that has a list of the groups that the user has chosen.
Problem 1: I can iterate through GroupsList and grab all the IDs. How do I translate the SQL 'WHERE ID IN(a string of comma delineated IDs)' for LINQ to SQL? Is that the best way to do that?
Problem 2: Once I have the list of BillingGroups I need to iterate through each group. For each group, I need to iterate through the BillingCodes. For each BillingCode I need to generate a WHERE clause that has all of the conditions in the BillingCode. I propose something like so:
for each BillingGroup in BillingGroups
for each BillingCode in BillingGroup.BillingCodes
where1 = "..."
next
next
Problem 3: Here's the part where I don't have a clue. I need to dynamically create a query in LINQ to SQL. Keep in mind that I don't know how many groups there'll be or how many codes are in each group.
There are 2 tables:
**transactions**
transaction_id
patient_id
[code]....
I have a query that can be summarised in SQL as follows;
Select
S.StockCode
From
StockToCheck As S
[Code]....
Where the S var is a list of strings. This gives the error 'S' is not declared and points to the S in the function call / join (GetPOSStock). So it does not seem possible to do this in Linq, can anyone confirm?
I have been on a hiatus from VB for some time. I was coding in C++ and C# for quite some years and on my venture back to VB, decided to put my trusty VB 6.0 on the shelf and try out the new 'rave' VB.NET. I'd first like to say, I can't imagine how different it is from older versions. I'm using Visual Basic 2005 and I find myself sometimes pulling my hair out over things that were common practice before, yet have been totally revamped. But I'm getting by, barely, but getting by.
My problem is this: I am writing an application that loads the Title field of a DataGrid (after being loaded from a DataTable of course) into a ListBox then sorts them. The problem is, upon sorting, I lose the original index value that pertains to that entry in the DataGrid. In other words, if the first ListBox item is selected, it contains the index value of the first entry in the DataGrid, which stores the rest of the data to fill the labels and controls on the form. I have a semi-workaround for this by iterating through the DataGrid and comparing the Title field to the text of the selected item in the ListBox, but the downside to this is that you could never have the same named item or you would only get data for the last item entered. My question is... Is there a way to somehow retain or store the original index values of a ListBox before sorting? If so, this would make my code a lot smoother and allow for multiple entries of the same name in the Title field of my database.
P.S. If someone could go through how to access items from the DataTable itself, I could get rid of the DataGrid altogether, as I don't need it other than to access the DB data. I couldn't figure out how to get at it while it is in the DataTable, so I loaded it into a DataGrid control and made it invisinel.
I have these objects:[code]Using LINQ I need to take a List(Of MakeInfo) and a List(Of ModelInfo) and aggregate the StockInfo from ModelInfo into the List(Of MakeInfo).So for each MakeInfo I will have a total count of all stock where MakeInfo.Name = ModelInfo.Make, and also a minimum price.I think it's going to be something like this, but I'm having trouble accessing the nested object and not sure if it's going to be possible with a single query.[code]
View 2 Repliesvb
Dim CheckedRows = From dgv As DataGridViewRow In Me.DataGridView4.Rows _
Where dgv.Cells(0).Value = True _
Select New With {.a = dgv.Cells(1).Value, .b = dgv.Cells(2).Value}
my code above works fine but how to get the index of the row on which the checkbox is checked
I was wandering is it possible to use a query within another query below is the code I am trying to use.
Public Function GetInventByComp(ByVal CompID As String) Using DC As New DataClassDataContext
'need to get company id's based off names? thats bad should be name from Id need to rethink this
Dim invent = (From C In DC.Inventors_Companies _
Where C.CompID = CompID _
Select C.InventorID).ToString
[Code]...
I was trying to us multiple values in a string like "1, 3, 5" but I can't seem to get that working either so I am trying to use just a single value now. Can anyone help me? "Yes I am new to this"
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.
I am writing a message system on my server, the xml is something like this
<xml>
<entry>
<sender>[code]....
my problem now i guess is 2 fold, i wish to combine the first 3 queries into a single query and place in a list or a collection or is there a way to do this with a single query that will give me my desired result?
I encountered something like a logical error which I could hardly resolve since I'm new to this technology. I'm using visual basic 2008 express edition with its built-in linq-to-sql technology. I was able to retrieve, add, edit, and delete such record using the linq-to-sql method, but one thing.I could not get is something like relational database operation. Here is my problem. As you can see the table above which represents the records on my database. You can notice there some account numbers that were duplicated which I used as the primary key or identifier. What I want is when I'd like to query such account number it should display all the records that have the same account numbers on it. Say for example, if I query the account number 00003. It should only pull up and display three records with the name Maverick and their corresponding address, movie rented and date.What is happening in my end is when I query such account number which are being duplicated in the database I encountered two things, its either it would display all the records in the database with different account numbers associated or it gives me an error message if I change my code from 'For Each memrec In db.Table3s' to 'For Each memrec In retrn' statement.What I've been trying to do here is if you enter the account number on the search box, it should only display the records on the combo box associated with the account number being entered. Like if you enter 00003 on the search box, it should only display the three movies rented by Maverick no more no less on the combo box. [code]
I have already tried that set of codes before but it's working the same thing. I tried many times modifying my codes before I posted my comment in this forum thinking that i can resolve it on my own but I wasn't able to. That code won't still filter the records in the database. I would like to verify that the table above is only representation but the real column on the table on my database is 'Account#' not Account Number and visual basic would detect the code as 'Account_'. May i know why Movies_Rented column on my table is not a member of string? Why is it the code you gave would still display all the records on the combo box? this is what im not getting. hope you can still find the solution to this issue.
Is there a way to convert a string into a linq query? Searching for those words brings up tons of stuff unrelated to what I'm trying to do..For instance, this works, of course...
Dim lstMyQuery = (From item in htMyTable.values where item(0) = "Apple" Select item)
But somehow I want to do this:
Dim strQuery = "From item in htMyTable.values where item(0) = " & CHR(34) & "Apples" & CHR(34) & " Select item"
Dim lstMyQuery = (Somehow run/convert strQuery as a query)
The reason is strQuery will be different each time depending on what the user has selected earlier in the program.R if lstMyQuery is already a collection, is there a way to add to it?
Dim lstMyQuery = (From item in htMyTable.values where item(0) = "Apples" Select item)
(this obviously doesn't work, but it's basically what I want to do...)
lstMyQuery.Add(From item in htMyTable.values where item(0) = "Oranges" Select item)
I have a LINQ query:[code]How can I pass "MyField" to the Sub and make the LINQ "Where" clause work?
View 2 Repliesi need to query the datatable & set the outcome as datagridview controls datasource
vb.net
Private Sub Txt_Search_TextChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Txt_Search.TextChanged
'routine objective:- Filter datatable & set the datagridview datasource
[code]....
I have a LINQ query that groups and counts on a single dgv cell. What I want to do is group and count on 2 dgv cells. So I modified my existing query by adding a SELECT statement highlighted :
CODE:
But I am getting an error on the second select variable stating: Range variable 'Value' is already declared
What I have read shows that I can select more than one variable.
What I am trying to achieve is this:
Original
CODE:
Result:
CODE:
I have the following xml document which would be taken from the web and stored into an XDocument object.
[Code]...
I have a generic dictonary which is templated in the following manner:
[code...]
If I wanted to omit certain list items against arbitrary keys (that is the items that are in the list contained within the value part of each of the key value pairs making up the dictionary) given some arbitrary condition (lets say omitting list items where a list item contained the string "abc")
I would expect to able to create/project into a new dictionary which would contain entries which contained lists WITHOUT those items whose name contained "abc"
How do I achieve this using a Lambda expression?
I was trying something like this:
[code..]
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
if there is that much of a performance gain in running a LINQ stored procedure versus a LINQ query?
View 1 RepliesI'm trying to do a LINQ Query against a typed datatable that will return me duplicated data.With out going into too much detail, here's the basic setup:
strCode1 - string type
intCode1 - int32 type
intAdjustor - int32
There are more fields but these are the ones that are important.I'm going to do my best to describe this, as it's kind of confusing.In theory intCode1 is a key for strCode1 (hence the names). So each time intCode1 is duplicated, the same strCode1 should appear. Example:
[code]...
Ultimately I'd like to get a List(Of T) - where T is my typed data row. In SQL, I would simply use a sub query, to get a distinct list of strCode1 and intCode1, then do a count, grouped by strCode1 where I get more than one row.I'm not sure how to translate that into LINQ, AND get the original types data rows returned in a list.