LINQ. Reducing The Code By Using Dynamic Queries?
Feb 17, 2011
I use the following code to fill the Table1 dictionary with the information found within the LINQ query.
Dim DB As New DatabaseDataContext
Dim Table1 As New Dictionary(Of String, Integer)
Dim Table2 As New Dictionary(Of String, Integer)
[code].....
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Jun 5, 2008
I've recently ported my website from 2005 to 2008, and I'm using LINQ Queries to implement a search. The issue is that none of the fields are mandatory, so I've had to implement a dynamic LINQ Query (sic?). Here's the relevant code -
Public Function searchQuery(ByVal titleType As String, ByVal titleName As String, _
ByVal configMgr As String, ByVal lifecycle As String, _
ByVal CIType As String, ByVal recordsPerPage As String) As IEnumerable(Of
[code].....
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Jul 3, 2011
I use the following code to fill the Table1 dictionary with the information found within the LINQ query.[code]....
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Jan 6, 2010
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?
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Feb 5, 2010
I would like to bind a DataGridView to a different LINQ query every time (in order to reuse the same form/DGV for different queries), like this:
[Code]....
but the "Qry", and the number of comboboxes, and their field names would change every time.
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Feb 8, 2012
I have a class with properties in it . The properties in it are all named the same with the columns names in the database.The reason for that is that i want to loop through all the properties within the class and dynamically create an sql query with the parameters in it . Then dynamically create the parameters and add them into the oraclecommand , everything works well until one of the properties ( QTY ) is set to 0 . When it is set to 0 , during the properties loop ,it will check it as nothing and bypasses the QTY property , with that i am missing one of the columns.class with properties , Notice the property Qty it is Nullable(Of Integer) , it is because when inserting data into the database , sometimes i would want it to be null instead of default 0 .
Public Class HDB
Public Property BONum() As String
Public Property Owner() As String
Public Property Qty() As Nullable(Of Integer)
[code]....
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May 27, 2011
How would you go about reducing the code for this but still allowing it to work the way it is now
Dim updatelesson As String = cmbChange.SelectedIndex
Dim chosenlesson As String = cmbSession.SelectedIndex
Dim changed As String = lstNames.SelectedItem
[CODE]....
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Mar 2, 2009
Reading through "The Pragmatic Programmer", I've come across the DRY (Don't Repeat Yourself) and Orthagonal (keep code modular) principles.I have a suite of modules, some of which have common procedures. Because each module is a separate project in Visual Studio, up until now I have simply copied code from one project to another when 1 module (project) needs to do the same function as another module (project). This is when functionality overlaps, not when 2 modules (projects) do everything the same.
I always suspected this was bad practice (and have seen the fruits of my suspicions when the subs get out of sync), and the book confirmed me in this belief. So, what I want to do is make a central code repository for the 4 or 5 common subs, but I don't know how to do it.Should I make a .dll file for each sub I want to use in multiple places? If so, how do I do that? Is there another way to do what I want to do?
1. I have a subroutine that takes a filepath (and if disconnected also a SqlConnection) and loads the referenced file into a database as a BLOB.
2. I have 3 separate projects in 1 VS solution that all run basically the same version of this code.
3. I want all 3 to run EXACTLY the same code.
4. I want 1 version of this code so that any changes made don't need to be made in 3 places.
5. I have a few other instances like this for other subroutines.
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Apr 4, 2012
I have managed to crunch down a several line code to this
For Each gal In galleries
With New HtmlGenericControl("div")
.ID = gal.Header
[code]....
I cannot find any where how to reference back to the object i am currently working with to add the control back to galleryContent' - Using plain me crashes the whole web server...Using does not offer the shorter hand of just using . - But it Using the only way to do it?
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Aug 27, 2007
Reducing Code Clutter When Using A ListItem Object
When using ListItem objects, the normal procedure is as follows:
[Code]......
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May 24, 2010
I need to represent the following query using LINQ:
DECLARE @PurchasedInventoryItemID Int = 2
DECLARE @PurchasedInventorySectionID Int = 0
DECLARE @PurchasedInventoryItem_PurchasingCategoryID Int = 3
DECLARE @PurchasedInventorySection_PurchasingCategoryID Int = 0
[code]....
Now, I know that a query in .NET doesnt look like this, this is my test in the SQL Design Studio. Naturally VB.NET variables will be used in place of the SQL local variables.My problem is this: All of the conditions after "WHERE" are optional. In that a query might be made that uses one, some, all, or none of the conditions. V.PropertyID and V.Value can also appear any number of times.In VB.NET I can make this query easy enough by simply concatenating strings, and using a loop to append the "V.PropertyID/V.Value" conditions.I can also make a Stored Procedure in MS SQL, which is easy enough.However, I want to accomplish this using LINQ.
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Aug 24, 2011
I have a basic grid of Linq2Sql entities (frmList). I have a separate form for editing (frmEdit). frmEdit has its own DataContext (as that appears to be the recommended way). How can I tell when my detail form has saved changes?
I don't see a built-in method. I am considering raising an event on the detail form when I save the datacontex, but not sure how I consume this event on frmList, and I have a feeling these events are already created for me somewhere?
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Oct 11, 2010
Let's say I have 3 tables: carts, baskets and eggs where a basket can contain many eggs and where carts contain many baskets. Each basket has a foreign key that maps to a cart and each egg has a foreign key that maps to a basket.I need to return a table that contains these 3 columns:Cart Name | Count of Baskets in Cart | Count of Eggs in Cart.Each table is an EF and I'm using linq with VB.So far, I have 2 queries: one that returns the columns Cart Name and Count of Basket and another one that returns Cart Name and Count of Eggs. How can I combine these two result tables so that I get the results in one table?
Dim query1 = (From cart In myEntities.Carts
Where cart.UserID = TheUserID
Join baskets In myEntities.Baskets On baskets.CartID Equals cart.CartID
[code]...
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Mar 13, 2012
I have a function used to filter a list of options to return only those that are lot traced, and, when applicable, also only show items matching a specified pattern:
Private Shared Function FilterResultsLot(ByVal source As IQueryable(Of Item), _
ByVal itemCode As String) As IQueryable(Of Item)
If HasFilter(itemCode, True) Then
[Code].....
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Mar 17, 2009
I have 2 tables that are related. Each app can relate to many apps. ie, office can be related to word, excel.[code]I would like to do the following query. I use vb.net but c# is ok.Query is to return all the apps that are not related to (1), so the result should be (4, quake) .
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Apr 5, 2011
I know there are similar questions on stackoverflow - and I looked through them and think my issue is somewhat similar, but haven't been able to find a solution by looking at any of these other questions/answers.I'm getting the error when attempting to execute the following code:
Private Sub btnReserve_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles btnReserve.Click
' Check that the room is still available.
Dim dbCheckOccupants As New pbu_housingEntities
Dim hall As String = CStr(Session("hall"))
[code]....
It is catching an error on this line:
Dim myID As String = GetID.First.id.ToString
As far as I can tell I'm not using multiple contexts?
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Apr 7, 2009
I decided to iterate through the Data.DataTable and trimmed the values there.Utilizing SirDemon's post, I have updated the code a little bit:
[code]...
I know that on the DisplayMember line the .First.Item() part is wrong, I just wanted to show what row I am trying to designate as the DisplayMember.
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Sep 10, 2009
Example-I have a person class
Public Class Person
Private _fname As String
Public Property Fname() As String
[Code]...
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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."
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Jul 6, 2010
I will start a new project, use the queries and dealing with databases using LINQ or SQl ,Which is better to start ???
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Oct 22, 2009
This is really a continuation from my earlier post. I've never worked with this datatype/collection (system.collection.generic.Ienumerable) before so I'm struggling to declare the query globally so I can reference the results within other sub routines/functions. I also am struggling to convert it to other types.how I can convert the collection of xml elements/system.collection.generic.Ienumerable into an xmltextreader (I know I will have to change the query below as it select the value of the node and not the node itself) I imagine by converting the query result to system.IO.stream My first port of call was MSDN but I find the material very difficult to understand for this particular subject.
[Code]...
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Sep 14, 2010
How would I get something like this to work so that I can dynamically alter the where-clause in this linq to sql query?
Dim AccountID = 1234
Dim AccountList
Select Case Types
[Code]....
With the above code I get this error:
Late binding operations cannot be converted to an expression tree
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Mar 14, 2011
I have been trying the following but it returns unexpected results:
Dim xd As XDocument = _
<?xml version="1.0" encoding="utf-8"?>
<root>
[code].....
The above result returns both 'element' nodes however it should only return the first where element/subelement@id=1/subsubelement@id=3 However if results.Ancestors. is used it returns the correct 'subelement' and if that line is not included it returns a single 'subsubelement' whih is also correct I don't understand why when mvoing to the 'element' it returns both (I realise both have a subelement with id=1 but I thought each further query would filter out the presvious results)?
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Feb 24, 2012
UPDATE: Groo's answer was marked correct as it would be a good alternative. I decided to stick with the select/switch statements to avoid the performance issues of using reflection. As far as I can tell there is no way to do what I want without using Dynamic LINQ (and reflection) or a decompiler (to manually code each LINQ statement, which I am already doing by hand). Note: to make this update DropDownList16 through DropDownList20 were removed (needed the characters).Is there a way to abstract the building of a dynamic Linq to SQL query?
I am trying to build a Linq to SQL query with a dynamic where clause, based on user supplied filters. The user needs to be able to filter strings, integers, and dates using advanced options (equal, not equal, contains, starts with, etc). The user needs to be able to use these filters with as many or few columns as desired.
[Code]...
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Jan 5, 2010
Dim query=Form f in BBSDb.Forms order by f.FormID Descending Select f where I want the f.FormID to be able to replace with a variable..What I mean is.. it doesn't have to f.FormID .. I may want to set f.FormName to be in descending for example using the code dynamically.. Is there anyway to achive?
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Mar 16, 2011
I want to write a query that the "where" in the query is a string something like"
Dim query as string= "Name =xxxx and Date > 10 "
Dim t = from book in doc.Descendants("books") Select _
[Name] = book..value, [Date] = book..value....
Where (query)
I build the query string on run time
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Oct 17, 2011
This is an extension of my last question which was answered, so I am starting a new thread. I have a query in LINQ that I was given to trim down the columns of a datatable. This works well, however, I need to make the LINQ query dynamic. So the query below:
Dim qColumnsIWant = From row As DataRow In inDT.AsEnumerable() _
Select _
EPN = row.Field(Of Integer)("EPNID"), _
EPNID = row.Field(Of String)("EPNNumber"), _
Ingot = row.Field(Of String)("Ingot"), _
ShopOrder = row.Field(Of String)("ShopOrder")
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Jan 24, 2010
I have been looking into dynamic querying of datasets and the use of copytodatatable() for a project. I have seen in alot of forums that the copytodatatable functionality is unusable as it was removed. have an example of a dynamic Linq query being loaded into a datatable.
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Jun 28, 2011
I have the following linq query:
Dim q = From definition In definitionList _
Where definition.ValueDefName.Contains(criteria)[code]....
I have already looked into this answer: LINQ - dynamic WHERE clause?Unfortunately, it doesn't work for me using .net 4.0. When I attempt to pass the criteria string in it ask for a predicate. The end goal is to add any of these:
definition.ValueDefname.Contains(criteria)
definition.ValueDefDesc.Contains(criteria)
definition.Aliaslist.Contains(Criteria)
definition.StrategicInitiative.Contains(Criteria)
to be passed into the query depending on what checkboxes the user has selected. How can I create a dynamic where clause in linq to sql? Is there new syntax for passing in a where clause as a string?
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Mar 16, 2011
I have a listbox which users can select from a list if Towns, I want to be able to build a LINQ query based on the selected items in the list e.g.
[Code]...
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