DataSource Controls :: How To Get Data From System.linq.iqueryable
May 26, 2010
I am using System.Linq.Dynamic to create the following query at runtime:
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I can then successfully display vMediaQ in a GridView.But I need to be able to access the individual fields (column headers and data) in vMediaQ, which is of type System.Linq.IQueryable.
If I have below code, how to make it work as it has below compile error:
Error: cannot implicitly convert type 'System.Linq.Iqueryable<system.data.DataSet> to 'System.Data.Dateset'. An explicit conversion exists.
public DataSet GetProductList() { using (var sdatabase = new DatabaseDataContext()) { IQueryable<DataSet> result = wmsdatabase.ExecuteQuery<DataSet>(@"SELECT productid, productname from product group by productid, productname").AsQueryable(); return result; // Compile error here } }
I have downloaded Visual Web Developer 2010 Express and am trying to use LINQ. In order to do that I have added a LINQ to SQL class to the web site and have dragged tables from the database view into the LINQ designer, which worked fine.But..When I add: using System.Data.Linq;to MainPage.xaml.cs, I receive an error:
Error 3 The type or namespace name 'Data' does not exist in the namespace 'System' (are you missing an assembly reference?)Even although I have references to System.Core, System.Data, System.Data.Linq in the website references.
Is there a way to do the following in VB:dim sTableClass as string = <my underlying table class in linq>dim dbTab as system.data.linq.table(<typed class of sTableClass>)I've tried cycling through the table objects of the linq data context and retrieved the following: Dim ddData = pkDB.GetTable(tt.RowType.Type.UnderlyingSystemType)(where tt reflects the row of the table I want to retrieve) But the expression returns and itable and I need the table equivalent but can't get this to work with a stri
I wanted to delete the record from data but I receive this error "Unable to cast object of type 'System.Data.Linq.DataQuery`1[training_eval.Course]' to type 'training_eval.Course'.
Dim eval_sure = From ev In db.Evaluates Where ev.course_id = indexcourse Select ev.course_id Dim del_course = From c In db.Courses Where c.Course_id = indexcourse db.Courses.DeleteOnSubmit(del_course) db.SubmitChanges()
I have a strange problem. I am adding a LinqDatasource object, and set the context:
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Then I get this error:The type 'System.Data.Linq.DataContext' is defined in an assembly that is not referenced. You must add a reference to assembly 'System.Data.Linq, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089'.
I have a query that joins two tables (in Linq) so I usethe result as an Iqueryable. I want the Query result to be displayed in a gridview, but for some reason I see nothing on the gridview.(I also tried without the join and just using the IQueryable result -and still nothing)
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why is doesn't work, or link me to an examlple that is similar - (Also is there another way to use the result of a "join" not as IQueryable)
I am having a lot of the same issue as this poster did with errors on initializing type.
I am trying to learn linq and am about ready to give up - don't get how this is easier...
I'm trying to do a simple update to product names in the product table based on the manufacturer ID
In order to do this I am looping through each record. I was initally successful with changing all names in the column but when I try to query the data, I continually run into multiple problems.
The following poster has had the same issue I have but his solution isn't working for me.
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I keep getting the same error on the opening bracket on the select statement in the SelectByManufacturerID function...
Error 1 Cannot initialize type 'DataBaseDataManagement.ProductName' with a collection initializer because it does not implement 'System.Collections.IEnumerable'
Button that does the actual updating...
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The function that the button calls to get the query... ERROR
I want to get the most recent Replies that is part of the Article
"Article.Replies" gets all the replies
So now I want to Order by Replies.Created by descending And then just take the first one from which i can get the members username fine. Im having a syntax problem with doing the orderby descending and by picking the first.
I'm creating a repository and service layer in my app, and my repo has a very simple function
Public Function GetRegions() As IQueryable(Of Region) Implements IRegionRepository.GetRegions Dim region = (From r In dc.Regions Select r) Return region.AsQueryable End Function
Now in my Service layer I've got a function like this
Public Function GetRegionById(ByVal id As Integer) As Region Implements IRegionService.GetRegionById Return _RegionRepository.GetRegions().Where(Function(r) r.ID = id).FirstOrDefault End Function
But i can't figure out how to add And r.isActive = True
I do some filtering on the IQueryable<MyType> object using the Contains() function in Linq, which in effect adds: MyColumn LIKE '%@MyParameter%' to the linq requestI want to make the function more generic, which could operate on a IQueryable object of an unknown type. In such case I do not know the type yet, therefore I can not add a standard .Contains() function. All I have present are the IQueryable object, the MyColumn and MyParameter as a string text. I need to be able to add "MyColumn LIKE '%@MyParameter%'" to the Linq object, dynamically ...
How can I write a piece of code that would run the Contains() on the IQueryable, knowing the Column name (as string) and the parameter value (as a string too) - I basically want to add this: MyColumn LIKE '%@MyParameter%' to the Linq where clause.
I have found something doing the .Where() function dynamically, but I do not entirely understand what is happening in there, so I struggle to convert it to Contains():
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adding dynamic .Contains() to the IQueryable object only using the string column name and the string value
in my web project i got an error that i couldnt find any solution. the error says: System.Security.SecurityException: Request for the permission of type 'System.Data.SqlClient.SqlClientPermission, System.Data, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089' failed. when i work in local there were no problem i put files to our server and i changed the database also. when i work in server in web application in Default.aspx i can connect db and get values without any problem using my DataLibrary
BUT the problem in my web service i also use my DataLibrary in webservice but when i try to run a method in web service it gives me the error which is : System.Security.SecurityException: Request for the permission of type 'System.Data.SqlClient.SqlClientPermission, System.Data, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089' failed.
All my pages are receiving this error - website is down; here's the code:
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Except my web config file shows linq is accounted for? [Code]....
I would note that I updated to VWD Express 2010 then had to revert back to 3.5 because my host at Arvixe had not updated my server yet. He then said he updated it and I reverted up to 4.0 again. It turned out he hadn't and I tried to revert back...and then this showed up and numerous other errors.
I am attempting to use SqlBulkCopy to import data from an XML document. I receive the following error when executing WriteToServer: Invalid cast from 'System.String' to 'System.Guid'
I am writing a plugin to help with a current ERP system we have that I am not allowed to modify the data structure at all. The table I am dealing with has over 100 columns and I am wanting to set my linq object propertychanged event and submitchanges or do I really have list out each property and set it equal to the new one?Below is an example of what I am trying to do:
Like that I have large number of controls on my form. I have dought, if I assigned like this, db.usp_ATI_FetchPatientDetails(iPatientID).ElementAt(0).Last_Name.ToString(); to every control, then I have set of controls like,
My question is that, for each control the Stored Procedure called or not? If it is yes then it is time consuming and I need to use LINQ to DataSet or LINQ to Object rather than to call SP for each control. What is difference between LINQ to DataSet and LINQ to Object?
I've just used Visual Studio to create a linq to sql class. In the .designer.cs file the code includes:using System.Data.Linq;However, when I compile the projeget:Compiler Error Message: CS0234: The type or namespace name 'Linq' does not exist in the namespace 'System.Data' (are you missing an assembly reference?)The code is completely generated by Visual Studio