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.
I have the following query in VB, but I do not know how to translate it to C# synatax
Dim q = From c In db.Customers Group Join o In db.Orders On c.CustomerID Equals o.CustomerID Into orders = Group Select New With {c.ContactName, .OrderCount = orders.Count()}
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 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?
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] .....
I'm out of my depth populating a windows form from an XML linq query (see code further down in post). The listbox is populated as intended, when a value is selected (row) I would like to populate the remaining form controls. The linq query I believe has created a new datatype "Anonymous Types". The query is only local to the load form subroutine but I'm not sure how to make it global.
When I define the query simply as an object the code in the selectedValueChanged event can't execute due to late databinding. how I can initially load the listbox from linq xml query and then populate the other controls when the value changes? Am I right in thinking even though the listbox is multi-columns (property) you can ONLY ever reference a row and NOT a column? I'm new to LINQ and Anonymous Types and the more I read the more confused I seem to get. On a less important note the order by is not functioning as intended (no errors) but data is always retrieved in xml file order and not by the node <text>. Also looked at using <text>.first to order the results without success.
Public Shared Function GetAllNotesByUser(ByVal UserID As Guid) As Account (??) Using db As New MyEntity Dim query= (From A In db.Account _
[Code].....
I would then like to pass this to another function to calculate the totals for all the accounts in the collection. Is it best practice to return an Ienumerable, a generic list, I'm just not sure what works best with LINQ and the entity framework.
SELECT C1, C2, C3 FROM T1 WHERE T1.C4='xyz' AND EXISTS (SELECT 1 FROM T2 WHERE T1.C17 = T2.C24) ORDER BY C3
I'm using EF CTP 5, so I have a DBContext variable named dbc, which includes DBSet objects T1s and T2s, based on POCOs T1 and T2.
In LINQ I write
DIM IND = From i In dbc.T1s Where i.C4 = "xyz" And (From t In dbc.T2s Where i.C17 = t.C24).Any Select i.C1, i.C2, i.C3 Order By C3
Running the query I get the error message "Unable to create a constant value of type 'T2'. Only primitive types ('such as Int32, String, and Guid') are supported in this context." When I omit the inner expression (third line in the LINQ code), the query runs fine. I tried switching the orders of the inner comparison, to be t.C24 = i.C17, with no effect.
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$AnonymousType_1 Part of the returned object.Am I even on the right track here or am I missing something completely?
I'm learning LINQ and VB and just spent an hour trying to access the fields of an anonymous type defined in a linq query. The key (I learned) is to convert the query to a list before you try to iterate through it with a for loop. How to access property of anonymous type in C#?
This does not work: edit (this compiles, but intellisense does not recognize the type)[code]...
Is that possible to get current Enumerator (...or iterator? Don't know which tern is the correct one) in a LINQ query ? For example, I try to create a XML output (via LINQ to XML) of all currently loaded assemblies. [code] is it possible to somehow get current "index" (counter?) from LINQ's Selects? I would like to use it in XML. [code]
Dim assSummary = From a In db.Assignments Join ur In db.UserRegions On a.Origin.ID Equals ur.Region.ID
[code]....
In the controller I can return the data easily as follows:
For Each c In assSummary MsgBox(c.Description & " " & c.AssCount) Next
If I pass the object through to the view using Viewdata("assSummary") = assSummary, how do I display the data? Every method I've tried results in messages about 'VB$AnonymousType_7(Of Integer,String) and I don't know how to retrieve the data from the anonymous type.
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'm trying to convert something from C# to VB.NET and I'm having trouble finding an equivlent in VB.NET to C#'s yield keyword. I realize 'yield' is not a convertable keyword to VB.NET, so can someone please show me how I would implement this code in VB.NET. I got all of it converted over except for the implemented GetEnumerator() function. It is simply a class that implements CollectionBase and IEnumerable (to make it LINQ worthy):
[Serializable()] public partial class Customers : CollectionBase, System.Collections.Generic.IEnumerable<BusinessLayer.Customer> {
Not sure if this is just a bad habit, or a valid way of doing things, but for large complex report queries spanning bunches of tables, I often get my aggregate stats by summing a Case statement.For example:
SELECT Contact.Name, SUM(CASE WHEN Order.Type = 'Special' THEN 1 ELSE 0 END) AS SpecialOrders, SUM(CASE WHEN Order.Type = 'Magic' THEN 1 ELSE 0 END) AS MagicOrders,
Some long-gone developer left the following LINQ query behind with no documentation and I'm struggling to understand what it does (and therefore if it's doing it right), either by breaking it into pieces or providing the SQL equivalent?
CODE:
I am struggling in particular with the Group Join and Into TargetMatches = Group pieces:
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
I'm used to webdeveloping, and when I work with databases, I usually use some text for the Text-property of a radio button, and the row's ID as Value-property. This makes it very easy to save to databases.
Is the an equivalent in winforms for the Value-property, or will I have to identify rows based on the text in the control?
I did a VB6 to VB.NET conversion and this line wasn't converted. I'm not sure what property to set that would replace Bevel. What could I use? statusBarMain.Items.Item("PercentBar").Bevel = System.Windows.Forms.Border3DStyle.SunkenOuter
What is equivalent property of Window.document in vb.net?Window.document it is the property in vb 6.0.What is equivalent property in vb.net?in vb.net Web browser.document property is available,but I want Window.document equivalent property in vb.net.
