LINQ - Can LinqPad Be Used Runtime Against Populated Classes
Jul 21, 2009
VB.net VS2008 My program dynamically populates a class as I click on specific calendar dates runtime. I am currently using various LINQ statements targeting this class for reporting purposes. However, all of my LINQ statements are hard-coded. Are there available solutions / modules which will provide me with a LINQ command and RESULTS window which can be set to an instance of a class so I can experiment with other commands runtime? Can LinqPad be used runtime against populated classes?
I have two classes, one nested in the other. [code]Neither "Name" or "ID" are unique between operations and records.I wish to construct a dictionary using LINQ = Dictionary(Of String, Of List(Of Integer), whereby the keys are uniqe examples of Names in my collection and the values are the collective set of distinct IDs that are associated with those names.
I have a project that currently uses an XML config file to create some groups. Based on these groups, you can search a database for information. What I want to do is create a form for editing that file. I can get to the information via messagebox, but when putting it into a ComboBox, I can't get the list updated. I have tried the text property which only populates the initial selection, and the Items is a read-only property. Nothing else looks close to what I want to do.
My other thought is to populate a datatable with the information and then populate the combo box from the database. It seems like an extra step that I shouldn't need, but it may be the only option right now.
The reason it can't be hardcoded is that the XML config file is already being used by a program, and the file may be updated from two or three computers, meaning I need a central location for the file.
I am having problems deleting any rows from a cascaded DGV. I get a run time error complaining that I am breaking a constraint almost as if LINQ is try to delete from the parent table. I have 2 DGVs on a form one displaying Species and the other all SubSpecies for the currently selected species and that works fine.
However when I try to delete a SubSpecies I get the following exception:- An attempt was made to remove a relationship between a Species and a SubSpecies. However, one of the relationship's foreign keys (SubSpecies.SpeciesID) cannot be set to null. At first I thought the error was raised by SQL server due to the Cascading Delete limitations on L2S but the error message for that is very different the DataContext.Log doesn't show any attempt to change the data.
The code used to bind the DGV's is as follows:-
Protected Sub BindControls() Try DC = New DataClassesWhatToPlantDataContext
I'm using a DataGridView to post the results of LINQ-from-SQL query. I was hoping that the data would be editable in the DataGridView, but it isn't. I made sure that DataGridView.readonly = false. I'm using VB.
VB 2008 DB = New CXToolDataContext() Dim Systems = (From TBLSYSTEMS In DB.tblSystems, TBLSYSTYPES In DB.tblSystemTypes _ Where TBLSYSTEMS.ProjectName = projectnumber And TBLSYSTEMS.SystemType =
I'm using LINQ to SQL as my data access layer for a new project.I have added my database tables to the designer and all is well.Whenever I use one of these classes in a function, Visual Studio warns me that 'Type xxxx is not CLS-compliant' or that 'Return type of function xxxx is not CLS-compliant' Is this a problem with the classes that LINQ to SQL generates? Does it matters? Can I disable these warnings anywhere? My VS error list is clogged up with these warnings making it hard to see anything else.
I need to generate a class at runtime similar to System.Resources where you can add a resource eg 'picture.bmp' and it immediatelly is accessible as 'System.Resources.picture.bmp'. I presume I need to generate XLM or/and XLSD at design time and then deserialise at runtime but I cant find a reference on how to do this. Specially without knowing the generic class in advance (as 'System.Resources' doesnt know all the resources in advance).
I am learningCreating LINQ to SQL Classes: Using the O/R Designer, the link is found below[url]...But when I Step #8 of Binding Controls on a Windows Form to Entity Classes says:8. Create an event handler for the Form_Load event by double-clicking the form. Add the following code to the event handler:
I am curious as to the proper technique to use SQL Server's AppRole with a LINQ to SQL Class. I understand I have to establish the intial connection with no connection pooling. However, do I simply call the SQL stored procedure sp_setapprole using standard LINQ before executing any of my methods that interact with the database, or is there a better way to enable and use AppRole within the LINQ to SQL class?
I am trying to learn OOD/OOP and read on the net that I am not supposed convert SQL tables into classes. But I cannot find an explanation why not to do it or which tables to skip. So I made an web application based on the below diagram. It works perfectly well. But I do not use OO. which table should not be mapped into a class and why not. do not use LINQ or NHibernate, etc as I do not understand them. I just need to understand the OOD.
I'm developing an application to allow engineers to conduct simple single table/view queries against our databases by selecting Database, Table, Fields.
I get how to use the Dynamic LINQ Library Sample to provide for dynamically selecting the Select, Where and Order by Clauses at runtime but I'm at an impass on how to allot for table choice.
Is there a way to provide for dynamically selecting the "from" table at run time
EDIT
So Both of the answers seem to be saying the same general Idea. I'm going to try to convert the C# into VB and get it to work.
The first answer converts to
NotInheritable Class DataContextExtensions Private Sub New() End Sub
The code below works fine on my development PC, but when I deployed the app, it crashes.
Here is the lines of code that are relvant
Private TdsTypesList As List(Of TDS_Type) ... TdsTypesList = (From tt In db.TDS_Types Select tt).ToList
[Code].....
I have many queries that are using linq, and none of them throw any errors. The set of data is not very large either, less that 100 rows. I dont know if I have any other queries that do not have where statements in them that work.
Running .net 3.5 without sp1 on the client machine, although I am running sp1 on my development PC. looking for a solution that doesn't require sp1 to be installed.
Edit Code breaks on the second line when remote debugging.
I looked over [URL] and tried the following, with the same error.
TdsTypesList = tl.OfType(Of TDS_Type)().ToList
I finally found a dirty workaround. Instead of pulling all of columns from that table, I was able to re-write the query to omit 1 column. This returns an object of anonymous type, and I can use that object. I still would like to know what causes this though.
I can't connect to the "Service-Based Data Base" or to the "Linq To Sql classes". I tried all that I've read in the Forums for days : ( I removed the VB 2008 and SQL 2205-2208, then upload VB 2008 from my CD only. I'm starting a Web Technology class in 2 weeks, and the complition of the book is my entry requirement.
How can I structure my classes so that the user interfaces though a single class while the supporting classes are hidden from their view? I think its best understood in an example:
Public Class MyInterface Public Economic as EconomicClass Public Sub New() MyBase.New()
[code].....
So you might ask why am I even separating them? It's strictly for others who will be working with this interface. I need to funnel them though a logical structure:
This way everything is already handled for them in the background and they only need to run the method they need. I don't know if I can have it both ways in VB.NET.
code For Each item As Reflection.FieldInfo In GetType(NameSpace.ClassWithNestedClasses).GetFields rtfAppend(item.Name & ":" & Tab & item.GetValue(Me)) Next For Each item As Reflection.PropertyInfo In GetType(NameSpace.ClassWithNestedClasses).GetProperties()
[code]...
which gets me the simple string vars and properties of my top class, but how can i apply this to loop through all sub classes and get there vars and props?
I have a combo box and onload I want the combobox to be populated with data in a field from the database. However, when I execute I receive an empty combo box please could someone look what am doing wrong..
Private Sub populatecmbprojtype() Dim cmd As New SqlCommand Dim conn As SqlConnection = GetDbConnection()
I am having a strang problem with button event handlers that I am creating at runtime.Actually if I set the form as startup form everything is working fine but when I set the main apllication form as startup form the events for buttons created at runtime are not firing.I am posting the code so that you can have a better look and see whts wrong?I have two classes under spotlight here "Class1" and "Grid"I am creating an instance of grid in class 1 and in a sub in grid I am creating buttons dynamically as follows and adding event handlers
For i As Integer = lIndex To uIndex Dim btn As New Button btn.Name = ds.Tables(tblName).Rows(i)(btnName).ToString
In the code below in the btnAmountEarnedClick event, the lblResults is not being populated.
Private Sub cboRecycleSelection_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cboRecycleSelection.SelectedIndexChanged
I have several combo controls that need to be populated with a specific ID and name. I want the user to choose the name and have the ID in the background. Later when the data is exported from the database the specific ID's are exported and not the names.
I see that I can create the items in the combobox rather easily using their names. However, how can I associate the ID number for each of the items. Private Sub frmReceipts_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
' Add receipt types to combo box cboReceipt.Items.Add("Monetary") cboReceipt.Items.Add("Inkind") cboReceipt.Items.Add("NSF") End Sub
I thought it would be better to have a seperate table with the different receipt types and then somehow connect/link the contents of this new table to the combo box on this form. However, I am at a loss on how to do this.
I tried binding a DataGridView to a DataSet using the DataSource property but no data appeared in the DataGridView. I placed a DataGridView in an empty form, making no property changes except for the name. I did not create columns in the DataGridView. In the form's load event I placed the following code for loading a dataset named ds Executing in debug mode, I confirmed that there was data in that dataset. No column headings or data appeared in the DataGridView. What am I doing wrongly? There are 34 fields (columns) in the DataSet - maybe it exceeds the capacity of a DataGridView.
I have set up a search form so that when the user enters a character, a search occurs. I have some code behind to do the search. The code I am using is as follows:
Javascript:
<script type="text/javascript"> function TextBox_OnKeypress() { document.getElementById("ctl00_MainForm_ibtnSearch").click();
Searching the internet finds no less than 700 different ways and opinions to accomplish what I'm trying to do, and I would just like to know the simplest, most bullet-proof way possible.
[Code]...
I simply want to extract the string "bar," which is inside <hostName></hostName>I can do this easily enough with simple string functions, but I'd like to do it with one of the .NET XML classes/methods.
How do I add rows that have already been populated. I saw a param that took an array. I have 8 columns, so would I need 8 elements in my array when I add them I have the code: me.datagridview1.rows.add() But I want to modify the data in the row using code, how would I go about doing this?
I'm using this line to populate my combobox with all files in my application path:
ComboBox1.Items.AddRange(IO.Directory.GetFiles(Application.StartupPath))This works fine, however it displays the path as well, and I only want to display the files with extension .txt
I am fairly inexperienced with using datatables in VB. My question is this: Can I access a particular column of a table by name if it is not defined elsewhere like when I populate a datatable using sqldataadapter.
[Code]...
Is this the way it can be done? I believe this is the case, but can't find any definitive examples online (probably not searching properly)
