Implement The .Find Method When Binding A BindingSource To LINQ (IEnumerable) Result?
Mar 15, 2008
I'm binding a DataGridView to a BindingSource to a LINQ IEnumerable, I found that the BindingSource.Find method throws an exception because .Find isn't implemented in IEnumerable (and the BindingSource just passes the call to it's DataSource). I need to use BindingSource.Find to select/highlight a particular row in the DataGridView.
Is there a feasable way to extend my DataContext to support this behavior w/o breaking anything else? I expected to find the code out there already, but I've searched exaustively with no luck.Without it, I cannot "move" the BindingSource using .Position and that's a pretty common use of the BindingSource I think.
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May 28, 2010
I've long since built a way around this, but it still keeps bugging me... it doesnt help that my grasp of dynamic LINQ queries is still shakey.
For the example:
Parent has fields (ParentKey, ParentField)
Child has fields (ChildKey, ParentKey, ChildField)
Pet has fields (PetKey, ChildKey, PetField)
[Code].....
The above Join call doesnt work. I sort of understand why it doesnt work, but hopefully it'll show you how I tried to accomplish this task.
After all this was done I would have appended a Select to finish the job.
I tried it with the PredicateBuilder with little success. I might not know how to use it right but it felt like it wasnt gonna handle the joining.
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May 9, 2011
I have an object called Result<T> that has a constructor which accepts an argument of IEnumerable<T>. I'd like to be able to pass in a datatable if possible.
I tried datatable.AsEnumerable(), but where I bind to the data it was complaining that 'MyProperty' is not a field or property on type 'DataRow' - which makes sense since 'MyProperty' isn't a property on 'DataRow', but it was a column in my datatable.Is there a way to convert a datatable to something that I can pass into the Result object and still have it bind to, say, a gridview?
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Mar 7, 2011
I want to search particular item in Binding Source for which i use BindingSource.Find() method, but it throws an exception "This operation requires an IBindingList". My binding source is bind to a .net class object.. I searched over the internet, but could not find the clear solution to achieve this task. The sample class code is given below:
Imports System.ComponentModel
Public Class Department
Private _code As Long
[Code].....
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May 17, 2009
In C#, when writing a function that returns an IEnumerble<>, you can use yield return to return a single item of the enumeration and yield break; to signify no remaining items. What is the VB.NET syntax for doing the same thing?
[Code]...
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Mar 1, 2012
I've searched everywhere for some example code for this, but I can't figure out how to bind data returned from a function that looks like this to a gridview or dataset.
Public Function GetCompanyList() As IEnumerable(Of BusinessUser)
Return (From companyList In CorporateLists
Select companyList.User).Distinct()
[code].....
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Jun 5, 2012
In VB.Net you can easily get the text value of the first child element of an XElement like so:Dim sChildValue = xeParent.<MyChild>.Value()Of course that syntax is not supported in C#, but it produces the same IEnumerable(Of XElement) result as the Elements() method. So we can rewrite the above like so:
Dim sChildValue = xeParent.Elements("MyChild").Value()This Value() extension method is handy because often you are working with small XML documents and you just want the first node that matches. (One thing that annoys me about this method is that it seems to return Nothing/null if the IEnumerable list is empty due to the specified element not being found. To work around this I have created my own ValueOrBlank() method that returns an empty string in that situation instead.)
My problem is that I can't do the same thing in C#:var sChildValue = xeParent.Elements("MyChild").Value(); // won't compile, can't find Value() method
I checked my references/imports and they match the VB.Net project where the same call works. Fortunately I am able to use my custom ValueOrBlank() extension method to accomplish the same thing. But I'm curious as to what's missing in my C# project. I tried right-clicking on the Value() method call in Visual Studio and clicking "Go To Definition" to see if the Object Browser could tell me where the extension method is kept, but it just shows the System.String class. Does that mean this is one of those sneaky VB.Net-only features that the compiler itself supports, like the XML Axis < MyChild > syntax?
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Jan 22, 2010
I have the follow Linq query that is in a web application that was converted from .NET 1.1 to 3.5:
dim objListOfFilteredDataRows = from datarows as datarow in objDataSet.tables(0).rows _
where datarows("SomeColumn") = SomeValue
I have the exact same query in an application that was created using .NET 3.5 and the query returns an IEnumerable. However the query in the converted application is returning:
{Name = "WhereEnumerableIterator`1" FullName = "System.Linq.Enumerable+WhereEnumerableIterator`1[[System.Data.DataRow, System.Data, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089]]"}
**Edit: When I highlight the expression, the intellisense says that it doesn't know the type of objListOfFilteredDataRows and assumes its a type of "Object". Why is the type not infered in the converted 1.1 application but is infered in the "native" 3.5?**
What am I missing here? How do I convert the "WhereEnumeratorIterator`1 to an IEnumerable?
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May 19, 2011
I am stuck trying to convert code that works in C to VB. The C code is:internal IEnumerable<GraphicsBase> Selection
[Code]...
I have read the stuff about how this has to be done in VB using GetEnumerator method, but I just can't seem to get it to work.
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Apr 4, 2012
How to give another function's returned value in LINQ Ienumerable.
Private function GetFruitColor(fruit) as string
'It returns fruit color.
'If valid fruit and color not available, it returns ""(empty string)
[code].....
'Below code is wrong. but please suggest me how to correct it. My intention is, I want output collection(say dictionary) of each fruitname and its color(returned by other function call) for all the fruits which the GetFruitColor is not nothing(it can be empty or valid string).
Dim query = _
fruits.Where(Function(fruit) k= GetFruitColor(fruit) if not k is nothing select fruit, k)
End Sub
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Dec 14, 2009
why the next example throws a System.ArrayTypeMismatchException?New Int16(){4,5,6}.Cast(of UInt16).ToArray()I expected that this line returned a UInt16 array containing 4,5 and 6.
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Oct 19, 2010
My particular example is fairly complex but I think the concept would apply equally to something like a logging system so I'll use that instead for ease of explanation. It's a ficticious example, please don't harp on or agonise over what is achitectually, programatically or morally wrong with the example itself
[Code]...
I don't want to 'cheat' and resort to a long-winded way of doing it when performance isn't critical here and I'm moderately confident it can be done in a single LINQ statement.
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Jun 18, 2009
Is there any particular reason why creating a reference to an object in an IEnumerable Linq query would be really slow? I have a Linq query list consisting of my own objects (count is about 200).I was doing a time-critical task, and this line (which was used a lot in a loop) took nearly a millisecond to execute:
Dim CurObject as MyClass = QueryResult(CurIndex)
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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, 2011
I have a DataRepeater that needs to display individual items from a List (Of T). The missing link between them is a BindingSource component.Everything works fine, i.e., the DataRepeater displays list items correctly, and I can add and delete items, even change using the TextBoxes on the DataRepeater.
The problem is that when I change the value of an item in the code, it doesn't get reflected on the DataRepeater. Only when I click a button on the form which executes this code:myBindingSource.ResetBindings(False)
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Mar 26, 2011
i need some help here, i want a result that shown a total number from student who passed some subjects. Let say there are 8 student who got A in subject chemistry, then the output should display result something like " there are 8 students who got A in chemistry". And also is it possible to combined the result, for example i want the output something like "there are "X" students who got A in chemistry and physics". where "X" is variable (number). it should trigger when winform is loaded. im using bindingsource.filter, but failed. because using bindingsource.filter need the input from user then it produce the output. whereas i want the result shown when the winform is loaded. How can i achieve this.
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Jun 14, 2011
My error is option strict doesnot allow late binding
[Code]...
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Jan 19, 2009
I'm following advice to load data to a DataTable, binding to a BindingSource then a DataGridView. But some exzamples I've found use a DataAdapter, not a DataTable. [code]
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Oct 24, 2010
how to search xml file and display the result in list box.then export a xml file to excel in the search result
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Dec 16, 2010
I tried using the linq Zip method on IEnumerable but it does not work for more than 2 arrays.Here is an example in Python of what I am trying to do(I got p - nested IEnumerable - and need q - another nested IEnumerable):
>>> l=['a','b','c']
>>> m=[1,2,3]
>>> n=['x','y','z'][code].......
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Aug 14, 2009
We are working with an existing native application (most likely written in VB) that loads assemblies and calls methods with "Late Binding." We do NOT have access to its source code. We want to implement this interface in C#, and have the native application call our C# assembly. Is this anything we have to do beyond matching the method names and method signatures to make it work?
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Jun 8, 2009
I've got a form - CMCConsole It pops up a dialog form for adding a new case.If the matter number in a textbox on that dialog form matches an existing cases matter number I would like to find it in the binding source of the CMCConsole form
Private Function CheckMatter(ByVal MtrNum As String) As Boolean
Dim cfIndex As Integer = CMCConsole.caseBS.Find("MatterNumber", MtrNum)
Dim cfIndex2 As Integer = CMCConsole.casefileBS.Find("MatterNumber", MtrNum)
[code]....
But it appear the filter for the CASE we were just on that is set on the binding source is keeping the FIND from seeing other cases.
caseBS.Filter = "CaseId=" & e.Node.Tag.ToString
Do I have to clear the filter in order to find a matter number in some other case??
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Jun 24, 2011
In my form, I have textbox + combobox to enter datas which are saved to ms access. I have search option too. Also i have DataGrid to show the result of the search. What I want now is, 1. To show the search result in the textbox/combox as well (I already am able to make the result show on datagrid)2. When there are multiple result showing on DataGrid, if i click on a particular result on DataGrid, let the textbox/combobox automatically loads the details of the one i clicked.
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Feb 5, 2009
I'm trying to use the bindingsource.find method to match a datarow column with a user entered text. I know that using BindingSource1.find("columnName", searchString) will work when the user enters the exact string. What I would like to know is how to find a row that is close to the string using a wildcard search... a good example I guess is:dim searchString as string = textbox1.text 'lets say the user enter "se"dim index as integer = myBindingSource.find("columnName", searchString) 'I would like to find the firs record that starts with "se"I can achieve the idea using the bindingsource.filter method but this will interfere with other parts of my application if the bindingsource is changed.
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Oct 29, 2009
In my application, I have a single table. Two of the fields in the table are COUNTY and CATNUM. Both are string.
I want to perform a FIND on both fields. I have no problem doing the search on CATNUM alone IF I set a FILTER first. Due to the size of the table, it takes a few seconds to set the filter. Once the filter is set, .FIND works quickly.
The customer has the option of setting a filter to work on one COUNTRY at a time. If they choose to do so, no problem.
If they don't have a filter set and they are using the entire table, then when the customer wants to search for a COUNTRY & CATNUM, I present a list of COUNTRIES in the table and a textbox for them to input the CATNUM.
Now I have the COUNRTY and CATNUM - how do I do the FIND? I already know that I can FILTER the table by COUNTRY then do the find but as I said before, it takes too long for the filter to be set (in my mind anyway!).
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Aug 4, 2011
I've created a bindingsource like this[code]...
the data. However, I neeed to retrieve user ID and Pwd for a given server from bdsServers. So far I was not able to do this. Googled like crazy
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May 23, 2012
I implemented a PagedModel class to wrap around IEnumerable to provide paging data for grids in my MVC app.I used Resharper's auto-generated Equality code telling it to check the data, total rows, page number, and page size fields.[code]I found the call to Equals(other._ModelData, _ModelData) peculiar, as AFAIK, this checks that it is the same object rather than that the contained items are the same. Because my tests were failing anyways, I went ahead and changed it to other._ModelData.Equals(_ModelData) with no success. Then I reflected into it at debug time and found that other._ ModelData.GetType().GetMethod("Equals",{GetType(Object)}).DeclaringType was Object! Obviously, that would result in the failed comparison.I came up with a solution to create a EnumerableEquals method which compares every item in the two enumerables to confirm the are the same, but it seems sloppy. Is there anything I can do to use the normal .Equals method? [code]
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Oct 1, 2006
I have a bindingsource that is connected to a table where tho fields determine uniqueness. During a refresh I would like to return to the row that the user was on when he clicked the refresh button. BindingSource.find only supports one column in so far as i have been able to infer. So how doi do it. Altering the table is out of the question. Besides searching on multiple fields is a common event. Like for example first and lastname or perhaps company and journal number.
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Sep 7, 2010
i am trying to locate the id of a field using the binding source, if i type the full id, it is locating it successfully no problem, but that is not what i want, i want to type 3 digits of the end of the id and be able to still locate that record. i triedusing wildcards with it "%" with no success any suggestions?
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Dec 13, 2011
Private Sub btnRPSearch_Click(sender As System.Object, e As System.EventArgs) Handles btnRPSearch.Click
Dim currentRecord As String = RprAuthNumTextBox.Text
[Code].....
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