Using LINQ To Return Element In Collection, Would Like To Return Nothing If Element Not Found?
Mar 3, 2011
I would like the following function to return Nothing if the element with the specified key is not in the collection. Instead, it returns an error - something to the effect of "no element found"
Public Class MyCollection
Inherits System.Collections.ObjectModel.Collection(Of MyType)
Public Function FindByActivityKey(ByVal searchValue As Integer) As MyType
I have been doing well and also I am a noob I know it and you know it a lot has started making sense and I am evening figuring new things out without using Google but of course I have hit another snag in my program so here goes
I am waiting for an email to arrive (the page automatically refreshes) and then I want to click the link (I do not need to click to open the email or anything like that) I also have the code to click and navigate to the address reason being it was the only way I could figure out how to stop it opening in a new window on IE
So my only problem is I need a way to check every x seconds for the element and then if its there proceed with my code and if its not wait and then check again or however this is done in VB.If this is not the way its done please point me in the right direction the code I am using to find and then navigate to the link is
Dim emailpageelements As HtmlElementCollection = WebBrowser2.Document.GetElementsByTagName("a") For Each emailver As HtmlElement In emailpageelements If InStr(emailver.InnerHtml, "https://twitter.com/account/confirm_email/") Then WebBrowser1.Navigate(emailver.InnerText)
Is this the most straight forward way to return a typed collection?Here's the key line of code which returns a implicit type of IEnumerable that used to manually loop through to manually recreated a TYPED collection. Is there any native LINQ way to return a typed sorted collection without this recreating of the collection? [code]
Public Shared Function GetAllNotesByUser(ByVal UserID As Guid) As Account (??) Using db As New MyEntity Dim query= (From A In db.Account _
[Code].....
I would then like to pass this to another function to calculate the totals for all the accounts in the collection. Is it best practice to return an Ienumerable, a generic list, I'm just not sure what works best with LINQ and the entity framework.
I am using NiceEdit to format text in text areas, it displays a toolbar over the specified text area, I created a test page, its working, I Response.Write the content of the text area after being formatted, and its okay, I created a break point to see whats being read, it was all fine.Now I moved to the real page where I should implement this text formatting, it simply did not do anything, the toolbar is shown and its working, but when I submit, nothing is being stored, i created a break point and the content of that text area was nothing, empty "".I went further and put Response.Write(textArea.text) then Response.End() and I got the error:XML Parsing Error: no element foundJust in case, the script I am using for the formatting NiceEdit toolbar, and this is the same script i used in my test page and worked just fine, the script is:
I have a number of rewrite rules for a lot of things that I did in IIS7, like removing trailing slashes, canonnical URLs, lowercase lettering, and such. IIS altered my web.config, and everything works fine on the website, like it should. But in the Visual Studio web.config, the opening < rewrite > statement is underlined in blue, and at the bottom of VS, it says that the element 'system.webServer' has invalid child element 'rewrite'. But this is how IIS made it. I didn't do this manually. Should I be concerned with this VS error, or should I just leave as be, since it's working how it should work? Here's an example of my web.config:
I am having problems finding an named object declared in XAML in my codebehind file.I want to initalize a ViewModel from inside my View. However I also need a reference to the ViewModel in my code behind file (basically for navigation support, handling events, etc. that I cannot do easily from my ViewModel)[code]However I get a null reference exception when I'm trying to access the ViewModel in my code behind:[code]Some more research shows that the FindName call for "ViewModel" in InitalizeComponent returns null. I tried reading up on XAML namescopes etc. but as far as I see, this should be a simple case and just work, no?
Is there a way to control the way a browser behaves such as if I click on this link it doesn't navigate to that link but instead show me the source code behind that button?
I need to randomly pick an element from an array and I can only use that element three times,I can randomly pick the element but how do I go about only using it three times.
I want to take a field from a table and place the content into a collection. The collection is not supposed to have any duplicates. This is my code sofar... It does not work. The NOT statement is supposed to only enter values into the collection, when the collection does not allready contain the matching string.
I would like to set up a custom app configuration element collection section like this
<logSectionGroup> <logSection name="Testttt"> <properties name ="Pride">[code]....
Properties would be the configuration element, and log section would be the configuration element collection.The problem is, I've only seen where you can have multiple instances of a single element instead of multiple elements.
The XML sample below has two records and each record has three similar Nodes (<datafield tag="500" >) What I want to accomplish is get the value of the second Node <datafield tag = "5000">. The fallowing code I gets the value for all three nodes but I want something like get elementat(1). I tried this but it didn't worked MsgBox(xEle.Elements.ElementAt(1).Value)
Code:
Dim xd As XDocument = XDocument.Load("C:UsersstopeteDesktopMarc_convertxml.xml") If xd IsNot Nothing Then Dim datafields = From datafield In xd.Descendants("datafield")
I'm adding an element to existing XML doc with the following code:
Dim theXMLSource As String = Server.MapPath("~/Demo/") & "LabDemo.xml" Dim nodeElement As XElement Dim attrAndValue As XElement = _
[code]....
It makes error like this:
System.NullReferenceException: Object reference not set to an instance of an object.Object reference not set to an instance of an object.Error line: nodeElement.Add(New XElement(attrAndValue))
Please excuse my stupidity, I tend to find the traversing XML overly complicated.
[Code]...
Once it gets to staffBio I get an error saying "Object reference not set to an instance of an object." obviously because that node does not exist. My question is how can I assign the value to a variable even when it is empty without having to do a conditional check before each assignment?
I'm editing XML element with the following XML: <?xml version="1.0" encoding="utf-8"?> <!--Test XML with LINQ to XML--> <LabSerivceInfo><LabService> <ServiceType>Copy</ServiceType> <Price>1</Price></LabService> [Code] ..... How to update the ServiceType and Price where ServiceType = varServiceType?
Using VB.NET (3.5), i have an ArrayList of Employees. I'm trying to build an XML representation (to feed another system) and one of the fields is a simple incrementing ID, starting at 1.[code]...
Using the XML elements below, I am trying to locate all table elements where they have a column@Name equal to a specific item such as "email" and return the Database@Location and Table@Name. My LINQ statement returns the proper table@name but for each element found returns the first database@Location for both. So my question is, how can I search for a column@Name and return the proper Database@Location and Table@Name [Code]
I'm trying to update an element in the XML document below:
Here's the code:
Dim xmldoc As XDocument = XDocument.Load(theXMLSource1) Dim ql As XElement = (From ls In xmldoc.Elements("LabService") _ Where CType(ls.Element("ServiceType"), String).Equals("Scan") _
[code]....
But, I got this error message:
Object reference not set to an instance of an object.Exception Details: System.NullReferenceException: Object reference not set to an instance of an object.Error line:ql.SetValue("23")
I'm a bit of a LINQ newbie and I was having some trouble with the following. I'm trying to perform a query using LINQ on an XML file and store the results in a list of DataClass objects that match the XML.I've got an XML file that is defined like this:
I have created a Data class to support this XML format. What I would like to do is create a LINQ Query to grab these 3 records and store them into a List of my DataClass. In order to support multiple Order elements, I have my class defined with a generic list of "Order" structs... It looks like this:
Public Class ASNData Private _field As String Private _value As String[code].....
how to grab the 3 order elements and store them into my list of Order structs.
It has two records and each record has three similar Nodes (<datafield tag="500">). What I want to accomplish is get the value of the second Node <datafield tag = "5000">. The following code I gets the value for all three nodes but I want something like get elementat(1).I tried this but it didn't worked.
MsgBox(xEle.Elements.ElementAt(1).Value) Dim xd As XDocument = XDocument.Load("C:UsersstopeteDesktopMarc_conv ertxml.xml") If xd IsNot Nothing Then Dim datafields = From datafield In xd.Descendants("datafield") Where (datafield.Attribute("tag").Value = "500")
I want to be able to reference an element in an array of structures by the name of the element in a visual basic 2010 function. For example
Public Structure myStruct Public element1 as string Public element2 as integer Public element3 as boolean
[code]...
Is it possible to reference a structures element by the element's name in a similar way to that shown above. The code shown above does not work, as the expression obj(i).[elementName] does not work as hoped.
I need to bind a textblock.text property to a single element in an observable collection, or array element, and have the text update using the INotifyPropertyChanged or INotifyCollectionChanged, whichever is best.
Most examples describe ways to bind listboxes or other list views to entire collections, but my application needs to update several textblocks on a screen depending on notification of a change in one or more elements of an array.
Is it possible to bind a single textblock to a single array element? Is it possible to get notification of the proper type that will update one or more of the textblocks if any assigned element changes?
I am trying to write a LINQ query which will return true if there are multiple objects which have a property with the same value.
Here is what I have come up with so far:
Formatters.Where(Function(f As DataModel.Formatter) _ Formatters.Select(Function(f2 As DataModel.Formatter) f2.Name.ToLower()).Contains(f.Name.ToLower())).Count > 1
However the above always returns true as long as their are more then 1 elements in the list?
I have a generic list - SupportedTypeGroups. Each SupportedTypeGroup has SupportedTypes property (generic list of SupportedType). How to construct a Linq query to locate SupportedType with required name?
I am using linq to fill a gridview with the information from an xml from code behind. I would like to order my Grid according to one of my elements in the xml ("value element").
gvResourceEditor.DataSource = (From resElem In resourceElements.Elements("data") _ Select New With { _ .Key = resElem.Attribute("name").Value, _ .Value = HttpUtility.HtmlEncode(resElem.Element("value").Value), _ .Comment = If(resElem.Element("comment") IsNot Nothing, HttpUtility.HtmlEncode(resElem.Element("comment").Value), String.Empty) _ }).OrderBy(?????)
I am new in LINQ world.I need an urgent help in reading the xml elements using LINQ with specific where condition.I need to find the max air_temp for a county i.e where county name = "Boone" and hour id = "06/03/2009 09:00CDT".[code]
I cannot find a way to get LINQ to spit out xml the way they want. Question is, can LINQ do it or do I need to resort to hardcoding the xml the old way before LINQ to XML?