C# - Generics And Linq - Create The Object Of XPQuery ?
Feb 6, 2012
I have got the list of Class Name as Follows: Type[] typelist = typeof(Sample.Students).Assembly.GetTypes();
Now i have complete list of all classes available in Sample NameSpace:
Now i want to get data through class I am using Devexpress Persistance class so basically i have to create XPQuert Object as follows: XPQuery<Employee> EmployeeQuery = new XPQuery<Employees>(XPODefault.Session);
But in my case Employee class will be listed in typelist variable..How can i create the object of XPQuery.. is it possible something like this: XPQuery<typeof(typelist[0].Name)> EMployeeQuery = new XPQuery<typeof(typelist.Name)> (XPODefault.Session);
I'm triying to make a function that add a 'where' clause to a query based in a property and a value. This is a very simplefied version of my function.
Private Function simplified(ByVal query As IQueryable(Of T), ByVal PValue As Long, ByVal p As PropertyInfo) As ObjectQuery(Of T) query = query.Where(Function(c) DirectCast(p.GetValue(c, Nothing), Long) = PValue) Dim t = query.ToList 'this line is only for testing, and here is the error raise[code].....
The error message is: LINQ to Entities does not recognize the method 'System.Object CompareObjectEqual(System.Object, System.Object, Boolean)' method, and this method cannot be translated into a store expression.Looks like a can't use GetValue inside a linq query.
Private Function simplified2(ByVal query As IQueryable(Of T)) query = From q In query Where q.GetType.GetProperty("Id").GetValue(q, Nothing).Equals(1)[code]....
I have a class called results which amongst other things has 3 internal Lists which contain 0 to n result objects each. One list has results whose answer property is integer,the next is Decimal and the last text. I many common properties like ID and I have a property on the Results class called Result which looks like this: -
Public ReadOnly Property Result(Index) As Object Get Select Case ResultTypeID
We have 3 databases providers we use to connect to our databases: DB2, MS SQL, and Interbase. I would like to create a single generic database wrapper class that can be used to talk to all three just by passing in the correct connection string, username, password, and the provider desired.
I don't want to have to add references and import all three providers in the database class. Is this possible?I have done this before in Java using the Class.forName() function.
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.
I am getting following error whenever I want to use IIf function inside entity framework query.
LINQ to Entities does not recognize the method 'System.Object IIf(Boolean, System.Object, System.Object)' method, and this method cannot be translated into a store expression.
How can I convert an object of type System.Data.Linq.DataQuery to System.Linq.IQueryable?I'm working with Visual Basic/Silverlight, and the source code of my query is as follows:
Public Function Get_Cli_Pag() As IQueryable(Of V_Cliente_Pagare) Dim Qry = From P In Me.Context.Pagares Join C In Me.Context.Codigos On C.Codigo
This was an experiment to see if I could create a fake array using generics instead of using an array. I decided to try it, because I may use it if I find any advantages to using it over an array. it works, I am just asking for a second or third opinion, have I screwed anything up, or is there an easier way to accomplish this? If I use it, it will be for a 2D game I am creating, and is used to draw the 2D screen graphics, placing an image based on what image identifier is located at what coordinates. The value stored in the fake array is an integer that disignates the graphic to draw and whether it is passible or not, i.e. 0 = a floor image, 501 = a wall image that is impassible (any image number > 500 is impassable) The Class definition:
I have an object that is defined as a global variable based on custom class. Within that class I have an event that gets fired a certain intervals. These events are fired on the same thread as where the object is declared. How do I create a global object, but have the events within that object fire on a separate thread?
I am trying to write an VBA application in Excel 2010 using "Microsoft Soap Toolkit 3.0" on 64 bit Windows 7 to consume an web service. But i got an error while initializing an object of SoapClient30.
I was create Access database with Access 2003. I create VB project with Visual Studio 2005 Standard With connection wizzard I create coonect with this Access database, select all tablesI see this database inside Data sources and inside Server explorer Test connection is OK When I drag and drop table from Data sources, Wizzard don't create DataGridView, DataSourceBinding etc .. and I see popup window with mesage: Object reference not set to an instance of an object and then "game over"
Under component services, a COM+ component is used by the company, right-clicking it and choosing 'Activation' tab will show the 'constructor string' that is used for DB server connection by all applications. How can I access it the simplest way possible?
I have a class library that contains a number of classes. I would like to dynamically create an instance of one of these classes, set its properties, and call a method.
Example:
Public Interface IExample Sub DoSomething() End Interface Public Class ExampleClass
I have the following line of Dim clients = From client In db.clients Select client Where client.ClientID = id
In debugging, the clients object populates perfectly, but how can get get data from the clients object? Like if the clients object has a FirstName property, how can I set a textboxes text property to that property from the clients object?
I thought it'd be something like:
tbClientFirstName.Text = clients.FirstName But that doesn't work.
I am developing an IT Asset Tracking application using VB 2005 and SQL Server 2005 Express edition. Will I need to create classes to represent objects such as Computers, Printers, Scanners/Faxes, Contracts, Purchase Orders etc or are there any other approaches.For example, if I am correct, I will have a class called Computer and its properties will include Make,Model,CPU,Hard Disk,Memory etc. Is this the right approach.
Computers can be split up into Desktop PC's, Servers and Notebooks. Would I have to create separate classes for these as well or would they be ok under the Computer class.Once I create an object from the class, how can I use the object to interact with the SQL db.I am a beginner to VB.NET 2005 therefore I am slowly getting to grips with OOP.
I can't quite figure out why this Linq Statement isn't working as i would expect:
[Code]....
I would assume that this would create a new collection of anonymous types, that would be distinct. Instead it creates a collection the size of the "ThisParentCollection" with duplicate "MyAnonymousType" in it (duplicate id's).
Is it possible using Linq to select the FirstName and LastName out of all the Bloops in the collection of Bloops and return a collection of Razzies? Or am i limited to a For-Loop to do my work?
To clear up any confusion, either VB or C# will do. Also this will probably lead to me asking the question of (What about using a "Where" clause).
I am trying to use a simple LINQ to Objects query.When I try to run my application I get the message:
System.InvalidOperationException was unhandled Message="An error occurred creating the form. See Exception.InnerException for details. The error is: Method not found: 'Void sharatTashlumimWS.paymentDetailsManager.set_ReleaseDate(System.DateTime)'." Source="WindowsApplication1" StackTrace:
I have a collection (IList(Of Sample)) of the following class:
Public Class Sample Public sampleNum As String Public volume As Integer[code].....
This collection is filled from a regex that gets passed over a file.What I want to do is use Linq to generate a collection of these for each unique samplenum using the following conditions.For each samplenum: Have the highest volume where the final is greater then one
If the sample has multiple records for this volume then pick the one with the the highest final
If the previous step leaves us with no records pick the record with the highest final ignoring volume
I am extremely new to Linq and just can't get my head around this. For now I have solved this using for each's and temporary lists but I am interested in how this would be handled using pure Linq.Sample Data:
I'm trying out some LINQ expressions and can't get them to work with the List class. Basically I want to be able to sort a list of custom objects by property type, however the C# LINQ syntax is KILLING me and I can't figure out how to convert it to VB
Class Foo Sub New(Name As String, Position As Integer) Me.Name = Name
I have an array of unknown (to the current method) class objects. I do know that each class has a property called "Number". I am trying to write a LINQ query where I am looking for the object with the next Number in sequence. AKA, I'm at Number 8, use a LINQ query to find the object where Number=9.
I have an object that may have been inflated via a plain old DataContext, or may just have been new-ed up with just its .ID property set. There's no way to know for sure. I'm looking to rehydrate the entire object from whatever is in the database. If the object was new-ed up, I can call .Attach() on the table object and refresh from the Data Context with no trouble. But, if the object was already inflated from the DataContext I get the error: "Cannot attach an entity that already exists.". There's no timestamp field or anything like that - just an integer primary key being used to control the rehydration. I'd like to know if there's a way to conditionally attach. Here's the code - it works the way I want it to, but this seems a hackish way to go about it:
' myDC is a shared instance of a vanilla DataContext... ' myObj is an instance of a linqed-up `SomeLinqObject` Dim tbl = myDC.GetTable(Of SomeLinqObject)()
