Linq - Select Single Item From Child Collection?
Jan 12, 2012I have a parent child collection objects and was wondering how to get a single item from the child collection using Linq
[Code]...
ADVERTISEMENT
LINQ - Select A *TYPED* Item In A Collection?
Mar 1, 2011Can I use LINQ to return an item in a collection that is the same TYPE as the items in the collection? I am a LINQ Noob trying to avoid looping.
Dim mostRecentlyCreatedQuestionnaire As ParentQuestionnaireItem =
CType((From P In questionnaireCollection Order By P.Metadata.CreateDate Descending).Take(1), ParentQuestionnaireItem)
I get an "unable to CAST" error when I include the CTYPE function. I kind of expected that error, but I imagine that if I coul dnot do this, LINQ's usefulness would be diminished and therefore assume that there must be a way..
Order A Collection Based On A Child Property Using LINQ Or A Lambda?
Jan 26, 2012I get the following string expression provided:"ChildObject.FullName" ...where ChildObject is an instance property on the MyObject1 type.ChildObject has a property named "FullName" and I want to sort a collection of type "MyObject1" based on this child properties "FullName" value.
I can do this all day long on properties directly on MyObject1 but I run into 2 challanges when doing it on a child instance and I can't get all the pieces working. The main 2 challanges are:
MyObject1 has a few different child property types so I can't hardcode the type for ChildObject. The string could be of any type.The sort expression is a String and not a known type.Above the value returned from the last line in the expression (if I run the code outsode the OrderBy method, does provide me the 'FullName' information I need. So the code must be close, but it still does not work.
Any ideas on how I can accomplish this? What I am trying to prevent is hardcoding a series of 'If' blocks on the child's type to then hardcode in its type to the sort or OrderBy method.
LINQ To XML, Only Can Get First Item In Collection?
Sep 8, 2010Here is an example of my xml doc:
<?xml version="1.0" encoding="utf-8"?>
<employeedata>
<employee>
<firstname>Bob</firstname>
<lastname>Anderson</lastname>
[Code]...
However, only the first phone number (Office) displays in the listbox. The phoneinfo collection has both <phone> elements, but the For Each statement doesn't seem to iterate thru.
Select A Single Object Using Linq In Program?
Mar 18, 2011I have done a lot of searching to what appears to be a simple LINQ problem but I can't figure out how to do grab an object out of a collection that has a specified minimum (or max value) without resorting to a sort like this[code]...
View 3 RepliesC# - LINQ - Select All In Parent-child Heirarchy
Mar 12, 2012I was wondering if there is a neat way do to this, that DOESN'T use any kind of while loop or similar, preferably that would run against Linq to Entities as a single SQL round-trip, and also against Linq To Objects. I have an entity - Forum - that has a parent-child relationship going on. That is, a Forum may (or in the case of the top level, may not) have a ParentForum, and may have many ChildForums. A Forum then contains many Posts.
What I'm after here is a way to get all the Posts from a tree of Forums - i.e. the Forum in question, and all it's children, grandchildren etc. I don't know in advance how many sub-levels the Forum in question may have. (Note - I know this example isn't necessarily a valuble use case, but the Forum object model one is one that is familar to most people, and so serves as a generic and accessible premise rather than my actual domain model.)
C# - LINQ To SQL Join Two Tables To Select Parent Table Twice Based On Two Different Columns From Child Table?
Aug 23, 2010I have two tables Employees and CafeLogs. Some employees can be cashiers and also customers at the Cafe shop.
Table structures:
Employees: EmployeeId(PK) , FirstName, LastName
CafeLogs: LogId (PK), CashierId, EmployeeId, Value, => CashierId and EmployeeId are the data from column EmployeeId of Empoyee table
Table relationship:
Employees 1:N CafeLogs (CashierId (FK))
[code]....
Right now I know how to select only LogId, Employee's name, and , Value, not with Cashier name yet.
Dim query = From log In db.CafeLogs _
Join emp In db.Employees On emp.EmployeeId Equals log.EmployeeId _
Select log.LogId, emp.FirsName, emp.LastName, log.Value
.net - Search The Collection Of A Collection In LINQ Where Clause?
Apr 15, 2009I've got the following ADO.NET Entity Framework Entity Data Model:I want to find all the Policyholders with both a Service of a given Id and also a Keyword of a given Status.
This LINQ Does Not Work:
Dim ServicesId As Integer = ...
Dim KeywordStatus As Integer = ...
Dim FoundPolicyholders = From p As Policyholder In db.PolicyholderSet.Include("Keywords").Include("Services") _
Where p.Services.Id = ServicesId _
And p.Keywords.Status = KeywordStatus _
Select p
The Where clause cannot search the p.Services and p.Keywords EntityCollections in that way.
[Code]...
Search The Collection Of A Collection In LINQ Where Clause?
Apr 15, 2011search the collection of a collection in my LINQ Where clause?
View 11 RepliesWhen Users Select Each Item Another Item Will Be Added To Second Listbox But It Is The First Selected Item
Jul 5, 2010In my application I have a listbox and SelectionMode should be MultiSimple because users need to see which items they selected. In another tab we have another listbox this one should show all the selection users had done in first tab. Private Sub
[Code]....
.NET LINQ - Count Of Collection Within Collection?
Apr 14, 2011Take the following scenario:
Public Class Store
Public Overridable Property Areas As List(Of Area)
End Class
Public Class Area
[code]....
What's the quickest way to get a total count of shelves for a store? I.e. for a store I get the total count of areas by using Areas.Count Or will I need to loop through each area and tally the count of shelves?
Filter Parent / Child Table In Linq Query Based On Entities In Child Table?
Jul 9, 2010I have a table (Projects) which is linked to projectVersions on projectID..projectVersions contains several columns on which I'd like to filter a returned project (and associated projectVersions) list. For example there is a "capacity" column and a "country" column. I am doing a filtered list of projects on one page and I'd like to include all projects where any one of the associated projectVersions has a capacity of 750ml and a country of "France" for example.It may be that a particular parameter is not set and so I pass a zero to indicate not to filter on that.I guess this needs some kind of subquery as when I try and do something like this: [code] it doesn't work as the "xxx" bit, being one-to-many, expects me to specify an item to get at the entities within and yet I want to query where ANY of the associated versions match one of the criteria.
View 1 RepliesCombobox Select - 2 Items From Single Select
Mar 7, 2012I am a beginer in vb.net. For a school project, i have chosen inventory control as the subject. WIth help from videos, i have developed some basic forms with adding/updating.
The product table design is like this:
Name
Type
Size
[Code]...
Now, i am designing the purchase/sales screens. I am showing the items name, qty, price in a datagrid. From the products table, I am able to select the 'ProductName' by giving it a combobox . I want the ProductSellingPrice also to appear in the next column of the grid.
Select An Item From A List Box And Click A Button And Have That Item Go Into Another Listbox With It's Price
Oct 13, 2011How someone would select an item from a list box and click a button and have that item go into another listbox with it's price? I seem to be stuck on this part.
Here's my code:
I want to select the first option from the first listbox and I want to put it into another listbox along with the price of that item on the same line in the listbox. I can't seem to figure out how to that.
Public Class Form1
Const dcmPRICE_STRESS As Decimal = CDec(595.0)
Const dcmPRICE_TIME_MANAGMENT As Decimal = 695
[CODE]...
Create A Child Window In Single Form?
Jun 18, 2009i am doing windows application in vb.net , i want to know how to create a child window in single form.
View 3 RepliesVS 2005 Show A Single MDI Child One At A Time Only?
Jun 26, 2009I would want to be able to show a single mdi child form only one at a time, what would be the most efficient way of doing this?
View 2 RepliesNhibernate Partial Eager Load Of Child Collection?
Jan 25, 2011If I have a parent object (Parent) which has a List(Of Child) objects as a many-one relationship. Is it possible to return a Parent with a subset of it's child objects (eagerly loaded)? I am using VB and Criteria.
e.g. If Parent 1 has 50 children (20 type X 30 type Y) and I want to return the Parent with a collection containing only type X.
I only want a collection with a size of 20 with it's eagerly loaded children?
Return A Collection Of Child Nodes From A Treeview Node?
Jul 17, 2010way to return a collection of treenodes which are children of a selected node? I can't find on MSDN a object of treenodes that is a collection of childnodes.
I have two treeviews, and I am writing code that will copy treenodes from one treeview to another treeview if it is selected. If a parent node is selected, I would also like to copy over all the children. If it is just a childnode, then I would like to copy just that.
Here is what I have so far.
Dim treeobj As TreeNode
treeobj = TreeView2.Nodes.Add(TreeView1.SelectedNode.Text)
If TreeView1.SelectedNode.Parent.Index.ToString Is System.DBNull.Value Then
[Code]...
VS 2010 Get Control Collection From Mdi Active Child Form?
Feb 23, 2010After getting the current mdi active child form, how can I get it's control collection so I can access their data?
View 8 RepliesAuto-select Treeview Item By Item Name?
Jul 26, 2011i have a treeview with 8 Root items, my program needs to add items to the treeview without me selecting the proper root or item, the root items have been coded so they cannot be deleted, but i'm not sure how to get the software to place data in a particular root by what its name is. when you add children the indexs change so im not sure where to begin. heres an example
[Code]...
Delete Item From List Box Select Next Available Item?
May 14, 2012how whould I go about deleteing an item from a listbox and it will select the next available item.you know like the treeview control selects the next node if you delete one.
View 2 Replies"System.ArgumentException: An Item With The Same Key Has Already Been Added." When Trying To Order An In-memory LINQ Query By A LINQ Association?
Jan 27, 2011We are doing a query against an in-memory collection of LINQ data objects. The wrinkle is that we are ordering by a column in a related table whose records have not necessarily been loaded yet (deferred loading:)
Dim oPkgProducts = _
From b In oBillPkg.BillProducts _
Where b.Successful.GetValueOrDefault(Common.X_INDETERMINATE) = _
[code]....
LINQ Where Statement In Collection?
Mar 28, 2012I have a Customer object which has a collection of ContactNumbers. Is it possible with LINQ to get a list of Customers where one of the contact numbers = '123'?
Public Class Customer
Public Overridable Property ContactNumbers As List(Of ContactNumber)
End Class
[Code].....
Insert SQL 2008 Parent And Child Rows In A Single Transaction?
Nov 13, 2010First, a little background (greatly simplified): I have two classes, one called Entity and one called Item which a subclass of Entity. They each store their individual properties in seperate SQL 2008 tables using TableAdapters generated by a strongly typed DataSet. The Entity class has a Save() method that looks like this:
Public Sub Save()
entityTableAdapter.Update(entityRow)
End Sub
[Code]....
Indeed, the SQL table does not contain a row in the Entity table with the necessary ID at this point because the transaction is not complete.
My goal is to prevent the Entity record from being inserted if inserting the Item record fails. I could write code to delete the Entity record again, but this does not seem very elegant to me...
Fluent NHibernate Not Mapping Child Rows To A Collection Property (DB2 Database)
Nov 4, 2011The tables described herein both utilize composite keys. I have a parent table that stores eligibility information per "case". The child table stores eligibility information regarding each individual associated with the case. The child records are differentiated by pin number to make them unique in the child table only.
I am using NHibernate v3.1 with Fluent NHibernate v1.2, both acquired via NuGet packages. The entities are mapped in using the Fluent NHibernate auto-mapper functionality. Any custom mapping is done in the mapping override method for each entity.
Another thing to know is that these tables do not have a "primary key" defined in DB2. They only have "unique keys", which are what you see in the composite key definition below (see code).
T0026_AG_ELIG is the name of the parent table and the corresponding POCO class.
T0265_AG_IN_ELIG is the name of the child table and the corresponding POCO class.
Problem:
The problem is that when I execute the query, all the data is queried, the parent record is successfully mapped to the class, but the returned child rows do not map into the collection on the parent class. NHibernate does generate the queries for the parent and child data. When I execute my own query against the database, the correct data for the conditions does come back. For some reason, the child records are just not being bound to the property on the parent (T0026) class.
Question:
What do I need to do to get the multiple rows coming back from T0265_AG_IN_ELIG to map to their corresponding class and load properly into the specified collection property on the parent class (T0026_AG_ELIG)?
Collection Property of Parent (T0026_AG_ELIG):
Public Overridable Property IndividualEligibilityRecords As IList(Of T0265_AG_IN_ELIG)
Mapping Override for Parent (T0026_AG_ELIG):
mapping.CompositeId() _
[Code].....
Use LINQ Add CHILD VALUE Always 1?
Jul 19, 2011Use LINQ add CHILD VALUE always 1?I have the Tables [code]...
View 1 RepliesEvery Nth Item In A Collection In .Net?
Dec 16, 2009Nearly identical to How can I get every nth item from a List<T>?But I'm having trouble turning
List<T> list = originalList.Where((t,i) => (i % 5) == 0).ToList();
Into VB.Net code.
Build A String From A Collection With Linq?
Oct 8, 2009I'm building flat file content from collections of strings.
Example collection: A, B, C, D, E, etc.
I want to be able to output these values to a string with line feeds in one swoop with Linq if possible.[cod]e...
Get Last Instance Of Collection Controls Using Linq?
Mar 6, 2012How to get the last instance of label control in List (of Control) using linq?
View 4 RepliesLinq Iterate A Control Collection?
Jun 29, 2009Private Function GetWebDataGridOKButtonId() As String
Dim ctls As ControlCollection = _
WebDataGrid1.Controls(0).Controls(0).Controls
[Code]....
This is not working for me. I am trying to iterate a control collection and return one control ID.