I'm basically brand new to LINQ. I've seen some examples that allow me to strong type objects using LINQ but I don't really understand them because they're in C#, which I guess lets you do different things with LINQ(I think?). [Code] I just want to get a list of all the products from the XML doc and put them into a Generics list.
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I think (?) this is about object design, and perhaps about structural and/or creational patterns. But a bit hard to say when I only know a couple of patterns yet.[code]But... what if we INSTEAD want each Product instance only to (in some way) refer to one instance of a specific list of Components. So we wan't to save the products list to one file, and the components list to another file. Then would I build the objects the same way, or different? So let's then say we have now Class B as below. [code]
1. Will not need to update each component variable of the products list when the components list changes.
2. If the Product object shall be shown in a DataGridView, for editing properties, it seems easier to implement the selection of the component property.
Is this wrong approach? Is it suitable in some cases, and if so, when? Are there other solutions I perhaps am not aware of that would be appropriate? Is this about structural design patterns? and if so, can the alternatives above be catagorized to some pattern type? I don't really know exactly what I'm looking for.. But I think probably I'm looking to understand whether the object design will be determined by the way the objects are saved.. And if i shall save the objects by serializing to file, vs saving to a database, would I create the business objects differently?
I'm trying to make the following snippet work in VB6 but it's one error after the other. can anyone make heads or tails of this?
Basically i'm after a little proggy which will store the names of a couple of products, calculate product code (first three and last three characters of product name) produce a list of products stcked with their initial stock levels, allow info on products be search for, allow the products to be purchased.
[code]...
y have this class
Private Class MyClass
Public Property propertyOne() as String
Public Property propertyTwo() as String
[code].....
I know boxing and unboxing part in arraylist but question is if I define only string in arraylist then there is no question of boxing or unboxing. What will be the difference.
View 1 RepliesI have been trying to use the Generics List as a means of storing a large amount of data that I am reading in from hardware. I defined a class called 'Datapoint', that has several public variables of type Double, and as I read in a number of points (this is of variable length, and could potentially be very large), for every point I create a new instance of 'Datapoint', update its fields and then add it to a List(of Datapoint) which I named 'Datalist'. All works fine, except when I come to reset the List, I do not know how to free up the allocated memory. I have attached some snippets of code,
[Code]...
I am trying to limit the size of my generic list so that after it contains a certain amount of values it wont add any more. I am trying to do this using the Capacity property of the List object but this does not seem to work.
Dim slotDates As New List(Of Date)
slotDates.Capacity = 7
How would people advice limiting the size of a list? I am trying to avoid doing a statement to check the size after an object is added.
I've got 2 seperated programs.
One is a program where you can select a product and select how many of them you want. Then the total price wil be displayedin a label. And the list of selected products will be saved in a .txt file.
The second program is an Edit program. The user can edit his selected products. Here he can change the total of a product.So if he had selected 1, he can change it to three or something. When the user clicks the button Save. The changes will besaved in the same .txt file and the total price will also be changed and displayed in program one.
Program one is compleet.Program two has problems and here i need your help:- the user can't make a change in the numbers, seems that the textbox is read-only or something. How to solve?- Then when i click save, the changed must be saved in the .txt ( i can't test this yet because no changes can't be made)- the total new price must be showed in program 1 (i think i programmed this well, but can you take a look)
Here is a part of my code of program 1:
CODE:
How can I get a new distinct list from an existing list using LINQ? This is what I have so far and it is not distinct but does give me a new list.
Dim tmpQryColumn = (From a In _allAudits
Select New CheckBoxListItem
With {.Id = a.AuditColumn, .Name = a.AuditColumn}
).Distinct()
_columnList = New List(Of CheckBoxListItem)(tmpQryColumn)
I have 2 classes
Public Class Shipper
Public Property ShipperID As Long
Public Property CreateDate As DateTime
[Code].....
How can I get a new distinct list from an existing list using LINQ? This is what I have so far and it is not distinct but does give me a new list.
Dim tmpQryColumn = (From a In _allAudits
Select New CheckBoxListItem
With {.Id = a.AuditColumn, .Name = a.AuditColumn}
[code]......
I have two generic lists, named ListA and ListB. Both ListA and ListB could potentially have duplicate items. What I would like to do is use LINQ to grab the items in ListB that are not in ListA, but I'm unsure how to do so.
View 8 RepliesI'm trying to create a list of days(integer) from a list of dates(date).
I tryed to do this....
[Code]...
This is what I want to do as seen in C#(loop against a list and fill another list from its data using Linq)
[Code]...
I am making a minor basket system which the user selects a number of products from a datagrid and it adds them to a basket using an array list (arrItemID).However on the ViewBasket form I want another datagrid however a query is formed listing the selected products. Though the datagrid seems to be empty (though the query when outputted to a text box is ideal. [code]
View 3 RepliesAssuming a base type of "Message"...
[Code]...
I would like to have one collection of Message objects which can be either PhoneMessages or MailMessages, so that I can iterate through the list and deal with each message based on what type it happens to be.
Attempting just to use .Add() fails, saying that I can't add an item of type PhoneMessage to a List(Of Message). Is there some elegant way to accomplish what I'm trying to do? I had thought I could accomplish this with generics, but I think there's a gap in my understanding. If it can be accomplished in .NET 2.0, that would be ideal.
I have several different lists I want to call. They all have the same format for the class:
id, value, description, order.
Instead of creating a bunch a classes to return the all of the many lists, I wanted to use generics and just tell it what kind of list to return. However, I can not figure out how to populate the classes.
Here are 2 examples of function in my calling code. This should indicate the type of list and the stored proc used to get the data:
Public Function getTheEyeColors()
Dim glEyeColors As New GenericList
Return glEyeColors.GetALList(Of EyeColor)("GetAllEyeColors")
End Function
[Code] .....
I am writing app in vb.net
I have two variables one with list of RoomRate and other with list of RoomTypes.
We have RoomRates and RoomTypes linked with RoomTypeInfo variable insite the RoomRate.
So how do i find the RoomTypes which donot have the RoomRates Defined.
My Sample Code:
class RoomType
property UIN as integer
property Title as string
end class
[Code]......
Trying to build a project that lets users click an item from a list of products (tabbed form). Once an item is selected (check box) find a way to store that item.Then when the user has finished selecting items they can click a button showing what they have selected in a new form that will open.Whats the best way to store what items they select? An Array?
View 2 RepliesI got an object of List<List<string>>I need to bring this into a ist<string>I have no idea how to do this with LINQ.
View 1 RepliesI am trying to use linq to query a List(of T) object, but when i type in my linq statement it comes back with the following error: Error57Expression of type 'System.Collections.Generic.List(Of BreakoutData)' is not queryable. Make sure you are not missing an assembly reference and/or namespace import for the LINQ provider.D:\Code\OLGA35\BreakoutByBusinessUnit.aspx17025D:\Code\OLGA35\
I have looked at my web.config and I have the imports:
<assemblies>
<add assembly="System.Core, Version=3.5.0.0, Culture=neutral, PublicKeyToken=B77A5C561934E089"/>
<add assembly="System.Web.Extensions, Version=3.5.0.0, Culture=neutral,
[CODE]...
I have put in several imports at the top of my page, but that hasn't helped
<%@ Page Language="VB" MasterPageFile="~/MasterPage.master" %>
<%@ Import Namespace="System.Collections.Generic" %>
<%@ Import Namespace="System.Core" %>
[CODE]...
I'm not sure what to do at this point.
Here is the code that is relevant:
Dim ListCollection As List(Of List(Of BreakoutData))
Dim GroupList As List(Of String)
Dim DataList As List(Of BreakoutData)
[CODE]...
Everything i've found on google just says to add in the System.Core, System.Data.Linq references, but as far as I can tell it all is setup correctly
I am trying to use linq to query a List(of T) object, but when i type in my linq statement it comes back with the following error:
Error57Expression of type 'System.Collections.Generic.List(Of BreakoutData)' is not queryable. Make sure you are not missing an assembly reference and/or namespace import for the LINQ provider.D:\Code\OLGA35\BreakoutByBusinessUnit.aspx17025D:\Code\OLGA35\
[code].....
I am trying to write a generic function that generates an Xelement based on a list of objects, and a property of the object[code]....
View 3 RepliesI'm using a program see here: Visual Basic Regular Expression Question. I enter letters and the program returns all possible combinations from list. I want change this line of code...
Dim result = fruits.Where(Function(fruit) Not fruit.Except(letters).Any())
If I have this list:
Dim fruit as List(Of string) from {"apple","orange","pear","banana"}
And I input "p a p l e r" then it would return "apple" and "pear", but if I enter "a p l e r" then it would return just "pear". The idea is to return all words, which can be made of entered letters without duplicating any single letter. How to optimize this Linq code?
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)'.
If I have a List(Of Guid) can I map those Guid's with a single Linq expression to a CheckboxList of values?
View 1 RepliesI trying to do what seems to be a simple thing but I'm having problems. The answers I find aren't working. I'm still getting casting exceptions:
Dim query = (From l In dePhl.cv_phil Where l.batch = strMmddyyyy
Select l.zipfile.Distinct)
Dim objFileList As List(Of String) = query.ToList() 'Error
[Code]....
Assume I have the following XML file:
<Movies>
<Movie ownerName="Ryan">
<Title>The Lord of the Rings Trilogy</Title>
[code].....
Public Sub adjectAllNormals()
Dim qry As LinkedList(Of CElement) = From elm In Elements
From id In SelectIDs()
Where elm.ID = id
Console.WriteLine(qry.Count)
End Sub
I have recently started using vs2008 for the linq feature but am having problems using it with a sorted list.my sorted list has a key of timestamp.I want to retrieve the first item from the sorted list having (key) timestamp <= myTimestamp.
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