Search Results

Search found 53332 results on 2134 pages for 'c to vb net'.

Page 47/2134 | < Previous Page | 43 44 45 46 47 48 49 50 51 52 53 54  | Next Page >

  • Why C# IntelliSense is delayed compared to VB.NET?

    - by Sphynx
    In VB.NET projects, errors are highlighted immediately after cursor leaves the line. IN C#, I have to wait several seconds for IntelliSense to highlight it. Also, C# version doesn't show all project errors in "Errors List", unless you start to build it. Actually, it seems to work differently in every way. Is it possible to adjust that behavior?

    Read the article

  • How to delete multiple rows from datatable in VB.net 2008 ?

    - by KuldipMCA
    How to delete multiple rows from datatable in VB.net 2008 with out looping ? I do not want to delete from database. I want to delete from Local data table. I know the Select Method and also Remove and Remove at method too. but that needs looping to delete the ROWs from Datatable. I have 40000 Rows and i want to Delete selected 1000 Rows from that Datatable.

    Read the article

  • how to implement a counter in label which decrements every time page is loaded in asp.net(vb)?

    - by Parth
    how to implement a counter in label which decrements every time page is loaded in asp.net(vb)? It would be better if that counter value is accessed from and updated into database.. I've tried this on buttonclick but the value is reset automatically to intial value everytime as the button is insert and page is reloaded Protected Sub InsertButton_Click(ByVal sender As Object, ByVal e As System.EventArgs) Dim entries As Label = FindControl("label1") entries.Text = entries.Text - 1 End Sub

    Read the article

  • Is there a way to prevent an ASP.Net webapp from clearing out page variables on VB side?

    - by Chapso
    I have a webapp in ASP.Net with a VB codebehind. I need a List variable I have declared to persist as long as the person is on the page, but currently any time a control posts back to the code, everything is cleared out. I am completely new to ASP.net, so I have no idea if this is even possible. Can it be done with a Session variable? Those seem to me to be limited to base types, but I could be wrong.

    Read the article

  • How do I use "Into" LINQ expression in VB.NET?

    - by SLC
    I'm converting from C# this LINQ expression. However, it does not seem to work. C# return (from w in fishSticks group w by w.FishQty into g orderby g.Key descending select g).First().First(); VB Return (From w In fishSticks Group w By w.FishQty Into g() Order By g.Key Descending Select g).First().First() Visual Studio turns g into g() itself and then gives me this error: Definition of method 'g' is not accessible in this context. Any ideas?

    Read the article

  • How to make a link button visible after another button has been clicked in asp.net(vb) in button_c

    - by Parth
    How to make a link button visible after another button has been clicked in asp.net(vb) in button_click() it says error as "Object reference not set to an instance of an object." i've done this in my code Protected Sub InsertButton_Click(ByVal sender As Object, ByVal e As System.EventArgs) Dim receipt As LinkButton = FormView1.FindControl("LinkButton1") ' receipt.Enabled = "true" ' receipt.EnableTheming = "true" ' receipt.EnableViewState = "true" receipt.Visible = "true" End Sub

    Read the article

  • Host AngularJS (Html5Mode) in ASP.NET vNext

    - by Shaun
    Originally posted on: http://geekswithblogs.net/shaunxu/archive/2014/06/10/host-angularjs-html5mode-in-asp.net-vnext.aspxMicrosoft had announced ASP.NET vNext in BUILD and TechED recently and as a developer, I found that we can add features into one ASP.NET vNext application such as MVC, WebAPI, SignalR, etc.. Also it's cross platform which means I can host ASP.NET on Windows, Linux and OS X.   If you are following my blog you should knew that I'm currently working on a project which uses ASP.NET WebAPI, SignalR and AngularJS. Currently the AngularJS part is hosted by Express in Node.js while WebAPI and SignalR are hosted in ASP.NET. I was looking for a solution to host all of them in one platform so that my SignalR can utilize WebSocket. Currently AngularJS and SignalR are hosted in the same domain but different port so it has to use ServerSendEvent. It can be upgraded to WebSocket if I host both of them in the same port.   Host AngularJS in ASP.NET vNext Static File Middleware ASP.NET vNext utilizes middleware pattern to register feature it uses, which is very similar as Express in Node.js. Since AngularJS is a pure client side framework in theory what I need to do is to use ASP.NET vNext as a static file server. This is very easy as there's a build-in middleware shipped alone with ASP.NET vNext. Assuming I have "index.html" as below. 1: <html data-ng-app="demo"> 2: <head> 3: <script type="text/javascript" src="angular.js" /> 4: <script type="text/javascript" src="angular-ui-router.js" /> 5: <script type="text/javascript" src="app.js" /> 6: </head> 7: <body> 8: <h1>ASP.NET vNext with AngularJS</h1> 9: <div> 10: <a href="javascript:void(0)" data-ui-sref="view1">View 1</a> | 11: <a href="javascript:void(0)" data-ui-sref="view2">View 2</a> 12: </div> 13: <div data-ui-view></div> 14: </body> 15: </html> And the AngularJS JavaScript file as below. Notices that I have two views which only contains one line literal indicates the view name. 1: 'use strict'; 2:  3: var app = angular.module('demo', ['ui.router']); 4:  5: app.config(['$stateProvider', '$locationProvider', function ($stateProvider, $locationProvider) { 6: $stateProvider.state('view1', { 7: url: '/view1', 8: templateUrl: 'view1.html', 9: controller: 'View1Ctrl' }); 10:  11: $stateProvider.state('view2', { 12: url: '/view2', 13: templateUrl: 'view2.html', 14: controller: 'View2Ctrl' }); 15: }]); 16:  17: app.controller('View1Ctrl', function ($scope) { 18: }); 19:  20: app.controller('View2Ctrl', function ($scope) { 21: }); All AngularJS files are located in "app" folder and my ASP.NET vNext files are besides it. The "project.json" contains all dependencies I need to host static file server. 1: { 2: "dependencies": { 3: "Helios" : "0.1-alpha-*", 4: "Microsoft.AspNet.FileSystems": "0.1-alpha-*", 5: "Microsoft.AspNet.Http": "0.1-alpha-*", 6: "Microsoft.AspNet.StaticFiles": "0.1-alpha-*", 7: "Microsoft.AspNet.Hosting": "0.1-alpha-*", 8: "Microsoft.AspNet.Server.WebListener": "0.1-alpha-*" 9: }, 10: "commands": { 11: "web": "Microsoft.AspNet.Hosting server=Microsoft.AspNet.Server.WebListener server.urls=http://localhost:22222" 12: }, 13: "configurations" : { 14: "net45" : { 15: }, 16: "k10" : { 17: "System.Diagnostics.Contracts": "4.0.0.0", 18: "System.Security.Claims" : "0.1-alpha-*" 19: } 20: } 21: } Below is "Startup.cs" which is the entry file of my ASP.NET vNext. What I need to do is to let my application use FileServerMiddleware. 1: using System; 2: using Microsoft.AspNet.Builder; 3: using Microsoft.AspNet.FileSystems; 4: using Microsoft.AspNet.StaticFiles; 5:  6: namespace Shaun.AspNet.Plugins.AngularServer.Demo 7: { 8: public class Startup 9: { 10: public void Configure(IBuilder app) 11: { 12: app.UseFileServer(new FileServerOptions() { 13: EnableDirectoryBrowsing = true, 14: FileSystem = new PhysicalFileSystem(System.IO.Path.Combine(AppDomain.CurrentDomain.BaseDirectory, "app")) 15: }); 16: } 17: } 18: } Next, I need to create "NuGet.Config" file in the PARENT folder so that when I run "kpm restore" command later it can find ASP.NET vNext NuGet package successfully. 1: <?xml version="1.0" encoding="utf-8"?> 2: <configuration> 3: <packageSources> 4: <add key="AspNetVNext" value="https://www.myget.org/F/aspnetvnext/api/v2" /> 5: <add key="NuGet.org" value="https://nuget.org/api/v2/" /> 6: </packageSources> 7: <packageSourceCredentials> 8: <AspNetVNext> 9: <add key="Username" value="aspnetreadonly" /> 10: <add key="ClearTextPassword" value="4d8a2d9c-7b80-4162-9978-47e918c9658c" /> 11: </AspNetVNext> 12: </packageSourceCredentials> 13: </configuration> Now I need to run "kpm restore" to resolve all dependencies of my application. Finally, use "k web" to start the application which will be a static file server on "app" sub folder in the local 22222 port.   Support AngularJS Html5Mode AngularJS works well in previous demo. But you will note that there is a "#" in the browser address. This is because by default AngularJS adds "#" next to its entry page so ensure all request will be handled by this entry page. For example, in this case my entry page is "index.html", so when I clicked "View 1" in the page the address will be changed to "/#/view1" which means it still tell the web server I'm still looking for "index.html". This works, but makes the address looks ugly. Hence AngularJS introduces a feature called Html5Mode, which will get rid off the annoying "#" from the address bar. Below is the "app.js" with Html5Mode enabled, just one line of code. 1: 'use strict'; 2:  3: var app = angular.module('demo', ['ui.router']); 4:  5: app.config(['$stateProvider', '$locationProvider', function ($stateProvider, $locationProvider) { 6: $stateProvider.state('view1', { 7: url: '/view1', 8: templateUrl: 'view1.html', 9: controller: 'View1Ctrl' }); 10:  11: $stateProvider.state('view2', { 12: url: '/view2', 13: templateUrl: 'view2.html', 14: controller: 'View2Ctrl' }); 15:  16: // enable html5mode 17: $locationProvider.html5Mode(true); 18: }]); 19:  20: app.controller('View1Ctrl', function ($scope) { 21: }); 22:  23: app.controller('View2Ctrl', function ($scope) { 24: }); Then let's went to the root path of our website and click "View 1" you will see there's no "#" in the address. But the problem is, if we hit F5 the browser will be turn to blank. This is because in this mode the browser told the web server I want static file named "view1" but there's no file on the server. So underlying our web server, which is built by ASP.NET vNext, responded 404. To fix this problem we need to create our own ASP.NET vNext middleware. What it needs to do is firstly try to respond the static file request with the default StaticFileMiddleware. If the response status code was 404 then change the request path value to the entry page and try again. 1: public class AngularServerMiddleware 2: { 3: private readonly AngularServerOptions _options; 4: private readonly RequestDelegate _next; 5: private readonly StaticFileMiddleware _innerMiddleware; 6:  7: public AngularServerMiddleware(RequestDelegate next, AngularServerOptions options) 8: { 9: _next = next; 10: _options = options; 11:  12: _innerMiddleware = new StaticFileMiddleware(next, options.FileServerOptions.StaticFileOptions); 13: } 14:  15: public async Task Invoke(HttpContext context) 16: { 17: // try to resolve the request with default static file middleware 18: await _innerMiddleware.Invoke(context); 19: Console.WriteLine(context.Request.Path + ": " + context.Response.StatusCode); 20: // route to root path if the status code is 404 21: // and need support angular html5mode 22: if (context.Response.StatusCode == 404 && _options.Html5Mode) 23: { 24: context.Request.Path = _options.EntryPath; 25: await _innerMiddleware.Invoke(context); 26: Console.WriteLine(">> " + context.Request.Path + ": " + context.Response.StatusCode); 27: } 28: } 29: } We need an option class where user can specify the host root path and the entry page path. 1: public class AngularServerOptions 2: { 3: public FileServerOptions FileServerOptions { get; set; } 4:  5: public PathString EntryPath { get; set; } 6:  7: public bool Html5Mode 8: { 9: get 10: { 11: return EntryPath.HasValue; 12: } 13: } 14:  15: public AngularServerOptions() 16: { 17: FileServerOptions = new FileServerOptions(); 18: EntryPath = PathString.Empty; 19: } 20: } We also need an extension method so that user can append this feature in "Startup.cs" easily. 1: public static class AngularServerExtension 2: { 3: public static IBuilder UseAngularServer(this IBuilder builder, string rootPath, string entryPath) 4: { 5: var options = new AngularServerOptions() 6: { 7: FileServerOptions = new FileServerOptions() 8: { 9: EnableDirectoryBrowsing = false, 10: FileSystem = new PhysicalFileSystem(System.IO.Path.Combine(AppDomain.CurrentDomain.BaseDirectory, rootPath)) 11: }, 12: EntryPath = new PathString(entryPath) 13: }; 14:  15: builder.UseDefaultFiles(options.FileServerOptions.DefaultFilesOptions); 16:  17: return builder.Use(next => new AngularServerMiddleware(next, options).Invoke); 18: } 19: } Now with these classes ready we will change our "Startup.cs", use this middleware replace the default one, tell the server try to load "index.html" file if it cannot find resource. The code below is just for demo purpose. I just tried to load "index.html" in all cases once the StaticFileMiddleware returned 404. In fact we need to validation to make sure this is an AngularJS route request instead of a normal static file request. 1: using System; 2: using Microsoft.AspNet.Builder; 3: using Microsoft.AspNet.FileSystems; 4: using Microsoft.AspNet.StaticFiles; 5: using Shaun.AspNet.Plugins.AngularServer; 6:  7: namespace Shaun.AspNet.Plugins.AngularServer.Demo 8: { 9: public class Startup 10: { 11: public void Configure(IBuilder app) 12: { 13: app.UseAngularServer("app", "/index.html"); 14: } 15: } 16: } Now let's run "k web" again and try to refresh our browser and we can see the page loaded successfully. In the console window we can find the original request got 404 and we try to find "index.html" and return the correct result.   Summary In this post I introduced how to use ASP.NET vNext to host AngularJS application as a static file server. I also demonstrated how to extend ASP.NET vNext, so that it supports AngularJS Html5Mode. You can download the source code here.   Hope this helps, Shaun All documents and related graphics, codes are provided "AS IS" without warranty of any kind. Copyright © Shaun Ziyan Xu. This work is licensed under the Creative Commons License.

    Read the article

  • Announcing Entity Framework Code-First (CTP5 release)

    - by ScottGu
    This week the data team released the CTP5 build of the new Entity Framework Code-First library.  EF Code-First enables a pretty sweet code-centric development workflow for working with data.  It enables you to: Develop without ever having to open a designer or define an XML mapping file Define model objects by simply writing “plain old classes” with no base classes required Use a “convention over configuration” approach that enables database persistence without explicitly configuring anything Optionally override the convention-based persistence and use a fluent code API to fully customize the persistence mapping I’m a big fan of the EF Code-First approach, and wrote several blog posts about it this summer: Code-First Development with Entity Framework 4 (July 16th) EF Code-First: Custom Database Schema Mapping (July 23rd) Using EF Code-First with an Existing Database (August 3rd) Today’s new CTP5 release delivers several nice improvements over the CTP4 build, and will be the last preview build of Code First before the final release of it.  We will ship the final EF Code First release in the first quarter of next year (Q1 of 2011).  It works with all .NET application types (including both ASP.NET Web Forms and ASP.NET MVC projects). Installing EF Code First You can install and use EF Code First CTP5 using one of two ways: Approach 1) By downloading and running a setup program.  Once installed you can reference the EntityFramework.dll assembly it provides within your projects.      or: Approach 2) By using the NuGet Package Manager within Visual Studio to download and install EF Code First within a project.  To do this, simply bring up the NuGet Package Manager Console within Visual Studio (View->Other Windows->Package Manager Console) and type “Install-Package EFCodeFirst”: Typing “Install-Package EFCodeFirst” within the Package Manager Console will cause NuGet to download the EF Code First package, and add it to your current project: Doing this will automatically add a reference to the EntityFramework.dll assembly to your project:   NuGet enables you to have EF Code First setup and ready to use within seconds.  When the final release of EF Code First ships you’ll also be able to just type “Update-Package EFCodeFirst” to update your existing projects to use the final release. EF Code First Assembly and Namespace The CTP5 release of EF Code First has an updated assembly name, and new .NET namespace: Assembly Name: EntityFramework.dll Namespace: System.Data.Entity These names match what we plan to use for the final release of the library. Nice New CTP5 Improvements The new CTP5 release of EF Code First contains a bunch of nice improvements and refinements. Some of the highlights include: Better support for Existing Databases Built-in Model-Level Validation and DataAnnotation Support Fluent API Improvements Pluggable Conventions Support New Change Tracking API Improved Concurrency Conflict Resolution Raw SQL Query/Command Support The rest of this blog post contains some more details about a few of the above changes. Better Support for Existing Databases EF Code First makes it really easy to create model layers that work against existing databases.  CTP5 includes some refinements that further streamline the developer workflow for this scenario. Below are the steps to use EF Code First to create a model layer for the Northwind sample database: Step 1: Create Model Classes and a DbContext class Below is all of the code necessary to implement a simple model layer using EF Code First that goes against the Northwind database: EF Code First enables you to use “POCO” – Plain Old CLR Objects – to represent entities within a database.  This means that you do not need to derive model classes from a base class, nor implement any interfaces or data persistence attributes on them.  This enables the model classes to be kept clean, easily testable, and “persistence ignorant”.  The Product and Category classes above are examples of POCO model classes. EF Code First enables you to easily connect your POCO model classes to a database by creating a “DbContext” class that exposes public properties that map to the tables within a database.  The Northwind class above illustrates how this can be done.  It is mapping our Product and Category classes to the “Products” and “Categories” tables within the database.  The properties within the Product and Category classes in turn map to the columns within the Products and Categories tables – and each instance of a Product/Category object maps to a row within the tables. The above code is all of the code required to create our model and data access layer!  Previous CTPs of EF Code First required an additional step to work against existing databases (a call to Database.Initializer<Northwind>(null) to tell EF Code First to not create the database) – this step is no longer required with the CTP5 release.  Step 2: Configure the Database Connection String We’ve written all of the code we need to write to define our model layer.  Our last step before we use it will be to setup a connection-string that connects it with our database.  To do this we’ll add a “Northwind” connection-string to our web.config file (or App.Config for client apps) like so:   <connectionStrings>          <add name="Northwind"          connectionString="data source=.\SQLEXPRESS;Integrated Security=SSPI;AttachDBFilename=|DataDirectory|\northwind.mdf;User Instance=true"          providerName="System.Data.SqlClient" />   </connectionStrings> EF “code first” uses a convention where DbContext classes by default look for a connection-string that has the same name as the context class.  Because our DbContext class is called “Northwind” it by default looks for a “Northwind” connection-string to use.  Above our Northwind connection-string is configured to use a local SQL Express database (stored within the \App_Data directory of our project).  You can alternatively point it at a remote SQL Server. Step 3: Using our Northwind Model Layer We can now easily query and update our database using the strongly-typed model layer we just built with EF Code First. The code example below demonstrates how to use LINQ to query for products within a specific product category.  This query returns back a sequence of strongly-typed Product objects that match the search criteria: The code example below demonstrates how we can retrieve a specific Product object, update two of its properties, and then save the changes back to the database: EF Code First handles all of the change-tracking and data persistence work for us, and allows us to focus on our application and business logic as opposed to having to worry about data access plumbing. Built-in Model Validation EF Code First allows you to use any validation approach you want when implementing business rules with your model layer.  This enables a great deal of flexibility and power. Starting with this week’s CTP5 release, EF Code First also now includes built-in support for both the DataAnnotation and IValidatorObject validation support built-into .NET 4.  This enables you to easily implement validation rules on your models, and have these rules automatically be enforced by EF Code First whenever you save your model layer.  It provides a very convenient “out of the box” way to enable validation within your applications. Applying DataAnnotations to our Northwind Model The code example below demonstrates how we could add some declarative validation rules to two of the properties of our “Product” model: We are using the [Required] and [Range] attributes above.  These validation attributes live within the System.ComponentModel.DataAnnotations namespace that is built-into .NET 4, and can be used independently of EF.  The error messages specified on them can either be explicitly defined (like above) – or retrieved from resource files (which makes localizing applications easy). Validation Enforcement on SaveChanges() EF Code-First (starting with CTP5) now automatically applies and enforces DataAnnotation rules when a model object is updated or saved.  You do not need to write any code to enforce this – this support is now enabled by default.  This new support means that the below code – which violates our above rules – will automatically throw an exception when we call the “SaveChanges()” method on our Northwind DbContext: The DbEntityValidationException that is raised when the SaveChanges() method is invoked contains a “EntityValidationErrors” property that you can use to retrieve the list of all validation errors that occurred when the model was trying to save.  This enables you to easily guide the user on how to fix them.  Note that EF Code-First will abort the entire transaction of changes if a validation rule is violated – ensuring that our database is always kept in a valid, consistent state. EF Code First’s validation enforcement works both for the built-in .NET DataAnnotation attributes (like Required, Range, RegularExpression, StringLength, etc), as well as for any custom validation rule you create by sub-classing the System.ComponentModel.DataAnnotations.ValidationAttribute base class. UI Validation Support A lot of our UI frameworks in .NET also provide support for DataAnnotation-based validation rules. For example, ASP.NET MVC, ASP.NET Dynamic Data, and Silverlight (via WCF RIA Services) all provide support for displaying client-side validation UI that honor the DataAnnotation rules applied to model objects. The screen-shot below demonstrates how using the default “Add-View” scaffold template within an ASP.NET MVC 3 application will cause appropriate validation error messages to be displayed if appropriate values are not provided: ASP.NET MVC 3 supports both client-side and server-side enforcement of these validation rules.  The error messages displayed are automatically picked up from the declarative validation attributes – eliminating the need for you to write any custom code to display them. Keeping things DRY The “DRY Principle” stands for “Do Not Repeat Yourself”, and is a best practice that recommends that you avoid duplicating logic/configuration/code in multiple places across your application, and instead specify it only once and have it apply everywhere. EF Code First CTP5 now enables you to apply declarative DataAnnotation validations on your model classes (and specify them only once) and then have the validation logic be enforced (and corresponding error messages displayed) across all applications scenarios – including within controllers, views, client-side scripts, and for any custom code that updates and manipulates model classes. This makes it much easier to build good applications with clean code, and to build applications that can rapidly iterate and evolve. Other EF Code First Improvements New to CTP5 EF Code First CTP5 includes a bunch of other improvements as well.  Below are a few short descriptions of some of them: Fluent API Improvements EF Code First allows you to override an “OnModelCreating()” method on the DbContext class to further refine/override the schema mapping rules used to map model classes to underlying database schema.  CTP5 includes some refinements to the ModelBuilder class that is passed to this method which can make defining mapping rules cleaner and more concise.  The ADO.NET Team blogged some samples of how to do this here. Pluggable Conventions Support EF Code First CTP5 provides new support that allows you to override the “default conventions” that EF Code First honors, and optionally replace them with your own set of conventions. New Change Tracking API EF Code First CTP5 exposes a new set of change tracking information that enables you to access Original, Current & Stored values, and State (e.g. Added, Unchanged, Modified, Deleted).  This support is useful in a variety of scenarios. Improved Concurrency Conflict Resolution EF Code First CTP5 provides better exception messages that allow access to the affected object instance and the ability to resolve conflicts using current, original and database values.  Raw SQL Query/Command Support EF Code First CTP5 now allows raw SQL queries and commands (including SPROCs) to be executed via the SqlQuery and SqlCommand methods exposed off of the DbContext.Database property.  The results of these method calls can be materialized into object instances that can be optionally change-tracked by the DbContext.  This is useful for a variety of advanced scenarios. Full Data Annotations Support EF Code First CTP5 now supports all standard DataAnnotations within .NET, and can use them both to perform validation as well as to automatically create the appropriate database schema when EF Code First is used in a database creation scenario.  Summary EF Code First provides an elegant and powerful way to work with data.  I really like it because it is extremely clean and supports best practices, while also enabling solutions to be implemented very, very rapidly.  The code-only approach of the library means that model layers end up being flexible and easy to customize. This week’s CTP5 release further refines EF Code First and helps ensure that it will be really sweet when it ships early next year.  I recommend using NuGet to install and give it a try today.  I think you’ll be pleasantly surprised by how awesome it is. Hope this helps, Scott

    Read the article

  • Problems with MembershipUser / System.Web.ApplicationServices when upgrading to .net 4

    - by DaveK
    I have a large vb.net web project that I am trying to updgrade to .net4/VS2010. During compile I get the following error: 'System.Web.Security.MembershipUser' in assembly 'System.Web, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a' has been forwarded to assembly 'System.Web.ApplicationServices'. Either a reference to 'System.Web.ApplicationServices' is missing from your project or the type 'System.Web.Security.MembershipUser' is missing from assembly 'System.Web.ApplicationServices'. I researched the issue and the error is accurate. I added a reference to System.Web.ApplicationServices but I am still having problems. The project does not seem to recognize that the reference has been added. Intellisense will not pick it up, I can not use it in an Import statement, etc ... The assembly is listed in the compile section of my web.config: <assemblies> ... <add assembly="System.Web.ApplicationServices, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/> </assemblies> Any ideas?

    Read the article

  • ASP.NET Setting Culture with InitializeCulture

    - by Helen
    I have a website with three domains .com, .de and .it Each domain needs to default to the local language/culture of the country. I have created a base page and added an InitializeCulture Protected Overrides Sub InitializeCulture() Dim url As System.Uri = Request.Url Dim hostname As String = url.Host.ToString() Dim SelectedLanguage As String If HttpContext.Current.Profile("PreferredCulture").ToString Is Nothing Then Select Case hostname Case "www.domain.de" SelectedLanguage = "de" Thread.CurrentThread.CurrentUICulture = New CultureInfo(SelectedLanguage) Thread.CurrentThread.CurrentCulture = CultureInfo.CreateSpecificCulture(SelectedLanguage) Case "www.domain.it" SelectedLanguage = "it" Thread.CurrentThread.CurrentUICulture = New CultureInfo(SelectedLanguage) Thread.CurrentThread.CurrentCulture = CultureInfo.CreateSpecificCulture(SelectedLanguage) Case Else SelectedLanguage = "en" Thread.CurrentThread.CurrentUICulture = New CultureInfo(SelectedLanguage) Thread.CurrentThread.CurrentCulture = CultureInfo.CreateSpecificCulture(SelectedLanguage) End Select End If End Sub This is fine. The problem now occurs because we also want three language selection buttons on the home page so that the user can override the domain language. So on my Default.asp.vb we have three button events like this... Protected Sub langEnglish_Click(ByVal sender As Object, ByVal e As System.Web.UI.ImageClickEventArgs) Handles langEnglish.Click Dim SelectedLanguage As String = "en" 'Save selected user language in profile HttpContext.Current.Profile.SetPropertyValue("PreferredCulture", SelectedLanguage) 'Force re-initialization of the page to fire InitializeCulture() Context.Server.Transfer(Context.Request.Path) End Sub But of course the InititalizeCulture then overrides whatever button selection has been made. Is there any way that the InitialCulture can check whether a button click has occurred and if so skip the routine? Any advice would be greatly appreciated, thanks.

    Read the article

  • Simulate Windows Service with ASP.NET

    - by Bayonian
    Hi, I have small web app that generate PDF files as a report. I'm trying to delete those generated PDF files after 10 sec that they are generated. What I want to do is to read a folder with PDF files every 10 sec, and delete all the PDF files inside that folder. I read this post of Easy Background Tasks in ASP.NET. The following code is the VB version. Protected Sub Application_Start(ByVal sender As Object, ByVal e As EventArgs) AddTask("DoStuff", 10) End Sub Private Sub AddTask(ByVal name As String, ByVal seconds As Integer) OnCacheRemove = New CacheItemRemovedCallback(CacheItemRemoved) HttpRuntime.Cache.Insert(name, seconds, Nothing, DateTime.Now.AddSeconds(seconds), Cache.NoSlidingExpiration, CacheItemPriority.NotRemovable, _ OnCacheRemove) End Sub Public Sub CacheItemRemoved(ByVal k As String, ByVal v As Object, ByVal r As CacheItemRemovedReason) ' do stuff here if it matches our taskname, like WebRequest DeletePDFilesInFoler() ' re-add our task so it recurs AddTask(k, Convert.ToInt32(v)) End Sub But I got this error Delegate 'System.Web.Caching.CacheItemRemovedCallback' requires an 'AddressOf' expression or lambda expression as the only argument to its constructor. If this code works, where I should put it. Right, now I'm putting it in the master page. How to get this error out? Thank you

    Read the article

  • Help understanding .NET delegates, events, and eventhandlers

    - by Seth Spearman
    Hello, In the last couple of days I asked a couple of questions about delegates HERE and HERE. I confess...I don't really understand delegates. And I REALLY REALLY REALLY want to understand and master them. (I can define them--type safe function pointers--but since I have little experience with C type languages it is not really helpful.) Can anyone recommend some online resource(s) that will explain delegates in a way that presumes nothing? This is one of those moments where I suspect that VB actually handicaps me because it does some wiring for me behind the scenes. The ideal resource would just explain what delegates are, without reference to anything else like (events and eventhandlers), would show me how all everything is wired up, explain (as I just learned) that delegates are types and what makes them unique as a type (perhaps using a little ildasm magic)). That foundation would then expand to explain how delegates are related to events and eventhandlers which would need a pretty good explanation in there own right. Finally this resource could tie it all together using real examples and explain what wiring DOES happen automatically by the compiler, how to use them, etc. And, oh yeah, when you should and should not use delegates, in other words, downsides and alternatives to using delegates. What say ye? Can any of you point me to resource(s) that can help me begin my journey to mastery? EDIT One last thing. The ideal resource will explain how you can and cannot use delegates in an interface declaration. That is something that really tripped me up. Thanks for your help. Seth

    Read the article

  • ASP.NET dropdownlist callback doesn't work inside div

    - by Wayne Werner
    This seems super weird to me. I have a callback handler done in VB which works fine with this code: <!-- Div Outside Form --> <div class="container"> <form id="querydata" runat="server"> <asp:DropDownList runat="server" ID="myddl" AutoPostBack="true" OnSelectedIndexChanged="myddlhandler"> <asp:ListItem>Hello</asp:ListItem> <asp:ListItem>Goodbye</asp:ListItem> </asp:DropDownList> <asp:Label runat="server" ID="label1"></asp:Label> </form> </div> <!-- Yep, they're matching --> I can change the value and everything is A-OK, but if I change the code to this (div inside form): <form id="querydata" runat="server"> <!-- Div inside form doesn't work :( --> <div class="container"> <asp:DropDownList runat="server" ID="myddl" AutoPostBack="true" OnSelectedIndexChanged="myddlhandler"> <asp:ListItem>Hello</asp:ListItem> <asp:ListItem>Goodbye</asp:ListItem> </asp:DropDownList> <asp:Label runat="server" ID="label1"></asp:Label> </div> </form> It the postback no longer works. Is how asp is supposed to work? Or is it some magic error that only works for me? And most importantly, if asp is not supposed to work this way, how should I be doing this? Thanks!

    Read the article

  • ASP.NET server data persistence

    - by Wayne Werner
    Hi, I'm not really sure exactly how the question should be phrased, so please be patient if I ask the wrong thing. I'm writing an ASP.NET application using VB as the code behind language. I have a data access class that connects to the DB to run the query (parameterized, of course), and another class to perform the validation tasks - I access this class from my aspx page. What I would like is to be able to store the data server side and wait for the user to choose from a few options based on the validity of the data. But unless my understanding is completely off, having persistent data objects on the server will give problems when multiple users connect? My ultimate goal is that once the data has been validated the end user can't modify it. Currently I'm validating the data, but I still have to retrieve it from the web form AFTER the user says OK, which obviously leaves open the possibility of injecting bad data either accidentally (unlikely) or on purpose (also unlikely for the use, but I'd prefer not to take the chance). So am I completely off in my understanding? If so, can someone point me to a resource that provides some instructions on keeping persistent data on the server, or provide instruction? Thanks!

    Read the article

  • April 30th Links: ASP.NET, ASP.NET MVC, Visual Studio 2010

    Here is the latest in my link-listing series. [In addition to blogging, I am also now using Twitter for quick updates and to share links. Follow me at: twitter.com/scottgu] ASP.NET Data Web Control Enhancements in ASP.NET 4.0: Scott Mitchell has a good article that summarizes some of the nice improvements coming to the ASP.NET 4 data controls. Refreshing an ASP.NET AJAX UpdatePanel with JavaScript: Scott Mitchell has another nice article in his series...Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

    Read the article

  • April 30th Links: ASP.NET, ASP.NET MVC, Visual Studio 2010

    Here is the latest in my link-listing series. [In addition to blogging, I am also now using Twitter for quick updates and to share links. Follow me at: twitter.com/scottgu] ASP.NET Data Web Control Enhancements in ASP.NET 4.0: Scott Mitchell has a good article that summarizes some of the nice improvements coming to the ASP.NET 4 data controls. Refreshing an ASP.NET AJAX UpdatePanel with JavaScript: Scott Mitchell has another nice article in his series...Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

    Read the article

  • Cannot iterate of a collection of Anonymous Types created from a LINQ Query in VB.NET

    - by Atari2600
    Ok everyone, I must be missing something here. Every LINQ example I have seen for VB.NET anonymous types claims I can do something like this: Dim Info As EnumerableRowCollection = pDataSet.Tables(0).AsEnumerable Dim Infos = From a In Info _ Select New With {.Prop1 = a("Prop1"), .Prop2 = a("Prop2"), .Prop3 = a("Prop3") } Now when I go to iterate through the collection(see example below), I get an error that says "Name "x" is not declared. For Each x in Infos ... Next It's like VB.NET doesn't understand that Infos is a collection of anonymous types created by LINQ and wants me to declare "x" as some type. (Wouldn't this defeat the purpose of an anonymous type?) I have added the references to System.Data.Linq and System.Data.DataSetExtensions to my project. Here is what I am importing with the class: Imports System.Linq Imports System.Linq.Enumerable Imports System.Linq.Queryable Imports System.Data.Linq Any ideas?

    Read the article

  • How to use SQL Expression Fields of Crystal Report 11.5 from VB.NET 2008

    - by Tareq
    I have the following SQL Expression Field in my Crystal Report 11.5 {fn CONCAT({fn CONCAT("SPR_PRODUCT"."PRODUCT_ID","SPR_PRODUCT_SUB_ITEM"."P_SUB_ITEM_ID" )},{fn CONCAT("SPR_PRODUCT_ITEM"."P_ITEM_ID","SPR_PRODUCT_GROUP"."P_GROUP_ID" )} )} It works well in the Preview Mode. But when I use the report in my VB.NET 2008 Project it says the following: Error in compiling SQL Expression : SQL Expressions can not be used in this report.. Error in File <...>.rpt: SQL Expression error: Error in compiling SQL Expression : SQL Expressions can not be used in this report... Please help me by telling how can I use the SQL Expression field in VB.NET ? Thanks in Advance.

    Read the article

  • paypal API in VB.net

    - by StealthRT
    Hey all, i have converted some C# PayPal API Code over to VB.net. I have added that code to a class within my project but i can not seem to access it: Imports System Imports com.paypal.sdk.services Imports com.paypal.sdk.profiles Imports com.paypal.sdk.util Namespace GenerateCodeNVP Public Class GetTransactionDetails Public Sub New() End Sub Public Function GetTransactionDetailsCode(ByVal transactionID As String) As String Dim caller As New NVPCallerServices() Dim profile As IAPIProfile = ProfileFactory.createSignatureAPIProfile() profile.APIUsername = "xxx" profile.APIPassword = "xxx" profile.APISignature = "xxx" profile.Environment = "sandbox" caller.APIProfile = profile Dim encoder As New NVPCodec() encoder("VERSION") = "51.0" encoder("METHOD") = "GetTransactionDetails" encoder("TRANSACTIONID") = transactionID Dim pStrrequestforNvp As String = encoder.Encode() Dim pStresponsenvp As String = caller.[Call](pStrrequestforNvp) Dim decoder As New NVPCodec() decoder.Decode(pStresponsenvp) Return decoder("ACK") End Function End Class End Namespace I am using this to access that class: Private Sub cmdGetTransDetail_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cmdGetTransDetail.Click Dim thereturn As String thereturn =GetTransactionDetailsCode("test51322") End Sub But it keeps telling me: Error 2 Name 'GetTransactionDetailsCode' is not declared. I'm new at calling classes in VB.net so any help would be great! :o) David

    Read the article

  • nservicebus compiler error "reference required to assembly nServicebus" in vb.net programs

    - by mgcain
    I downloaded the nServicebus binaries as of May 17th and have two different vb.net projects (one in .net 3.5, the other in .net 4.0) that both have the error "Reference to Assembly nServicebus, Version 2.0.0.1145, culture=neutral, PublicKeyToken=9fc386479f8a226c containing the type NServicebus.IStartable. Add one to your project. I have in the references already nServicebus.dll, nservicebus.Core.dll, and log4net.dll

    Read the article

  • How to find and fix performance problems in ORM powered applications

    - by FransBouma
    Once in a while we get requests about how to fix performance problems with our framework. As it comes down to following the same steps and looking into the same things every single time, I decided to write a blogpost about it instead, so more people can learn from this and solve performance problems in their O/R mapper powered applications. In some parts it's focused on LLBLGen Pro but it's also usable for other O/R mapping frameworks, as the vast majority of performance problems in O/R mapper powered applications are not specific for a certain O/R mapper framework. Too often, the developer looks at the wrong part of the application, trying to fix what isn't a problem in that part, and getting frustrated that 'things are so slow with <insert your favorite framework X here>'. I'm in the O/R mapper business for a long time now (almost 10 years, full time) and as it's a small world, we O/R mapper developers know almost all tricks to pull off by now: we all know what to do to make task ABC faster and what compromises (because there are almost always compromises) to deal with if we decide to make ABC faster that way. Some O/R mapper frameworks are faster in X, others in Y, but you can be sure the difference is mainly a result of a compromise some developers are willing to deal with and others aren't. That's why the O/R mapper frameworks on the market today are different in many ways, even though they all fetch and save entities from and to a database. I'm not suggesting there's no room for improvement in today's O/R mapper frameworks, there always is, but it's not a matter of 'the slowness of the application is caused by the O/R mapper' anymore. Perhaps query generation can be optimized a bit here, row materialization can be optimized a bit there, but it's mainly coming down to milliseconds. Still worth it if you're a framework developer, but it's not much compared to the time spend inside databases and in user code: if a complete fetch takes 40ms or 50ms (from call to entity object collection), it won't make a difference for your application as that 10ms difference won't be noticed. That's why it's very important to find the real locations of the problems so developers can fix them properly and don't get frustrated because their quest to get a fast, performing application failed. Performance tuning basics and rules Finding and fixing performance problems in any application is a strict procedure with four prescribed steps: isolate, analyze, interpret and fix, in that order. It's key that you don't skip a step nor make assumptions: these steps help you find the reason of a problem which seems to be there, and how to fix it or leave it as-is. Skipping a step, or when you assume things will be bad/slow without doing analysis will lead to the path of premature optimization and won't actually solve your problems, only create new ones. The most important rule of finding and fixing performance problems in software is that you have to understand what 'performance problem' actually means. Most developers will say "when a piece of software / code is slow, you have a performance problem". But is that actually the case? If I write a Linq query which will aggregate, group and sort 5 million rows from several tables to produce a resultset of 10 rows, it might take more than a couple of milliseconds before that resultset is ready to be consumed by other logic. If I solely look at the Linq query, the code consuming the resultset of the 10 rows and then look at the time it takes to complete the whole procedure, it will appear to me to be slow: all that time taken to produce and consume 10 rows? But if you look closer, if you analyze and interpret the situation, you'll see it does a tremendous amount of work, and in that light it might even be extremely fast. With every performance problem you encounter, always do realize that what you're trying to solve is perhaps not a technical problem at all, but a perception problem. The second most important rule you have to understand is based on the old saying "Penny wise, Pound Foolish": the part which takes e.g. 5% of the total time T for a given task isn't worth optimizing if you have another part which takes a much larger part of the total time T for that same given task. Optimizing parts which are relatively insignificant for the total time taken is not going to bring you better results overall, even if you totally optimize that part away. This is the core reason why analysis of the complete set of application parts which participate in a given task is key to being successful in solving performance problems: No analysis -> no problem -> no solution. One warning up front: hunting for performance will always include making compromises. Fast software can be made maintainable, but if you want to squeeze as much performance out of your software, you will inevitably be faced with the dilemma of compromising one or more from the group {readability, maintainability, features} for the extra performance you think you'll gain. It's then up to you to decide whether it's worth it. In almost all cases it's not. The reason for this is simple: the vast majority of performance problems can be solved by implementing the proper algorithms, the ones with proven Big O-characteristics so you know the performance you'll get plus you know the algorithm will work. The time taken by the algorithm implementing code is inevitable: you already implemented the best algorithm. You might find some optimizations on the technical level but in general these are minor. Let's look at the four steps to see how they guide us through the quest to find and fix performance problems. Isolate The first thing you need to do is to isolate the areas in your application which are assumed to be slow. For example, if your application is a web application and a given page is taking several seconds or even minutes to load, it's a good candidate to check out. It's important to start with the isolate step because it allows you to focus on a single code path per area with a clear begin and end and ignore the rest. The rest of the steps are taken per identified problematic area. Keep in mind that isolation focuses on tasks in an application, not code snippets. A task is something that's started in your application by either another task or the user, or another program, and has a beginning and an end. You can see a task as a piece of functionality offered by your application.  Analyze Once you've determined the problem areas, you have to perform analysis on the code paths of each area, to see where the performance problems occur and which areas are not the problem. This is a multi-layered effort: an application which uses an O/R mapper typically consists of multiple parts: there's likely some kind of interface (web, webservice, windows etc.), a part which controls the interface and business logic, the O/R mapper part and the RDBMS, all connected with either a network or inter-process connections provided by the OS or other means. Each of these parts, including the connectivity plumbing, eat up a part of the total time it takes to complete a task, e.g. load a webpage with all orders of a given customer X. To understand which parts participate in the task / area we're investigating and how much they contribute to the total time taken to complete the task, analysis of each participating task is essential. Start with the code you wrote which starts the task, analyze the code and track the path it follows through your application. What does the code do along the way, verify whether it's correct or not. Analyze whether you have implemented the right algorithms in your code for this particular area. Remember we're looking at one area at a time, which means we're ignoring all other code paths, just the code path of the current problematic area, from begin to end and back. Don't dig in and start optimizing at the code level just yet. We're just analyzing. If your analysis reveals big architectural stupidity, it's perhaps a good idea to rethink the architecture at this point. For the rest, we're analyzing which means we collect data about what could be wrong, for each participating part of the complete application. Reviewing the code you wrote is a good tool to get deeper understanding of what is going on for a given task but ultimately it lacks precision and overview what really happens: humans aren't good code interpreters, computers are. We therefore need to utilize tools to get deeper understanding about which parts contribute how much time to the total task, triggered by which other parts and for example how many times are they called. There are two different kind of tools which are necessary: .NET profilers and O/R mapper / RDBMS profilers. .NET profiling .NET profilers (e.g. dotTrace by JetBrains or Ants by Red Gate software) show exactly which pieces of code are called, how many times they're called, and the time it took to run that piece of code, at the method level and sometimes even at the line level. The .NET profilers are essential tools for understanding whether the time taken to complete a given task / area in your application is consumed by .NET code, where exactly in your code, the path to that code, how many times that code was called by other code and thus reveals where hotspots are located: the areas where a solution can be found. Importantly, they also reveal which areas can be left alone: remember our penny wise pound foolish saying: if a profiler reveals that a group of methods are fast, or don't contribute much to the total time taken for a given task, ignore them. Even if the code in them is perhaps complex and looks like a candidate for optimization: you can work all day on that, it won't matter.  As we're focusing on a single area of the application, it's best to start profiling right before you actually activate the task/area. Most .NET profilers support this by starting the application without starting the profiling procedure just yet. You navigate to the particular part which is slow, start profiling in the profiler, in your application you perform the actions which are considered slow, and afterwards you get a snapshot in the profiler. The snapshot contains the data collected by the profiler during the slow action, so most data is produced by code in the area to investigate. This is important, because it allows you to stay focused on a single area. O/R mapper and RDBMS profiling .NET profilers give you a good insight in the .NET side of things, but not in the RDBMS side of the application. As this article is about O/R mapper powered applications, we're also looking at databases, and the software making it possible to consume the database in your application: the O/R mapper. To understand which parts of the O/R mapper and database participate how much to the total time taken for task T, we need different tools. There are two kind of tools focusing on O/R mappers and database performance profiling: O/R mapper profilers and RDBMS profilers. For O/R mapper profilers, you can look at LLBLGen Prof by hibernating rhinos or the Linq to Sql/LLBLGen Pro profiler by Huagati. Hibernating rhinos also have profilers for other O/R mappers like NHibernate (NHProf) and Entity Framework (EFProf) and work the same as LLBLGen Prof. For RDBMS profilers, you have to look whether the RDBMS vendor has a profiler. For example for SQL Server, the profiler is shipped with SQL Server, for Oracle it's build into the RDBMS, however there are also 3rd party tools. Which tool you're using isn't really important, what's important is that you get insight in which queries are executed during the task / area we're currently focused on and how long they took. Here, the O/R mapper profilers have an advantage as they collect the time it took to execute the query from the application's perspective so they also collect the time it took to transport data across the network. This is important because a query which returns a massive resultset or a resultset with large blob/clob/ntext/image fields takes more time to get transported across the network than a small resultset and a database profiler doesn't take this into account most of the time. Another tool to use in this case, which is more low level and not all O/R mappers support it (though LLBLGen Pro and NHibernate as well do) is tracing: most O/R mappers offer some form of tracing or logging system which you can use to collect the SQL generated and executed and often also other activity behind the scenes. While tracing can produce a tremendous amount of data in some cases, it also gives insight in what's going on. Interpret After we've completed the analysis step it's time to look at the data we've collected. We've done code reviews to see whether we've done anything stupid and which parts actually take place and if the proper algorithms have been implemented. We've done .NET profiling to see which parts are choke points and how much time they contribute to the total time taken to complete the task we're investigating. We've performed O/R mapper profiling and RDBMS profiling to see which queries were executed during the task, how many queries were generated and executed and how long they took to complete, including network transportation. All this data reveals two things: which parts are big contributors to the total time taken and which parts are irrelevant. Both aspects are very important. The parts which are irrelevant (i.e. don't contribute significantly to the total time taken) can be ignored from now on, we won't look at them. The parts which contribute a lot to the total time taken are important to look at. We now have to first look at the .NET profiler results, to see whether the time taken is consumed in our own code, in .NET framework code, in the O/R mapper itself or somewhere else. For example if most of the time is consumed by DbCommand.ExecuteReader, the time it took to complete the task is depending on the time the data is fetched from the database. If there was just 1 query executed, according to tracing or O/R mapper profilers / RDBMS profilers, check whether that query is optimal, uses indexes or has to deal with a lot of data. Interpret means that you follow the path from begin to end through the data collected and determine where, along the path, the most time is contributed. It also means that you have to check whether this was expected or is totally unexpected. My previous example of the 10 row resultset of a query which groups millions of rows will likely reveal that a long time is spend inside the database and almost no time is spend in the .NET code, meaning the RDBMS part contributes the most to the total time taken, the rest is compared to that time, irrelevant. Considering the vastness of the source data set, it's expected this will take some time. However, does it need tweaking? Perhaps all possible tweaks are already in place. In the interpret step you then have to decide that further action in this area is necessary or not, based on what the analysis results show: if the analysis results were unexpected and in the area where the most time is contributed to the total time taken is room for improvement, action should be taken. If not, you can only accept the situation and move on. In all cases, document your decision together with the analysis you've done. If you decide that the perceived performance problem is actually expected due to the nature of the task performed, it's essential that in the future when someone else looks at the application and starts asking questions you can answer them properly and new analysis is only necessary if situations changed. Fix After interpreting the analysis results you've concluded that some areas need adjustment. This is the fix step: you're actively correcting the performance problem with proper action targeted at the real cause. In many cases related to O/R mapper powered applications it means you'll use different features of the O/R mapper to achieve the same goal, or apply optimizations at the RDBMS level. It could also mean you apply caching inside your application (compromise memory consumption over performance) to avoid unnecessary re-querying data and re-consuming the results. After applying a change, it's key you re-do the analysis and interpretation steps: compare the results and expectations with what you had before, to see whether your actions had any effect or whether it moved the problem to a different part of the application. Don't fall into the trap to do partly analysis: do the full analysis again: .NET profiling and O/R mapper / RDBMS profiling. It might very well be that the changes you've made make one part faster but another part significantly slower, in such a way that the overall problem hasn't changed at all. Performance tuning is dealing with compromises and making choices: to use one feature over the other, to accept a higher memory footprint, to go away from the strict-OO path and execute queries directly onto the RDBMS, these are choices and compromises which will cross your path if you want to fix performance problems with respect to O/R mappers or data-access and databases in general. In most cases it's not a big issue: alternatives are often good choices too and the compromises aren't that hard to deal with. What is important is that you document why you made a choice, a compromise: which analysis data, which interpretation led you to the choice made. This is key for good maintainability in the years to come. Most common performance problems with O/R mappers Below is an incomplete list of common performance problems related to data-access / O/R mappers / RDBMS code. It will help you with fixing the hotspots you found in the interpretation step. SELECT N+1: (Lazy-loading specific). Lazy loading triggered performance bottlenecks. Consider a list of Orders bound to a grid. You have a Field mapped onto a related field in Order, Customer.CompanyName. Showing this column in the grid will make the grid fetch (indirectly) for each row the Customer row. This means you'll get for the single list not 1 query (for the orders) but 1+(the number of orders shown) queries. To solve this: use eager loading using a prefetch path to fetch the customers with the orders. SELECT N+1 is easy to spot with an O/R mapper profiler or RDBMS profiler: if you see a lot of identical queries executed at once, you have this problem. Prefetch paths using many path nodes or sorting, or limiting. Eager loading problem. Prefetch paths can help with performance, but as 1 query is fetched per node, it can be the number of data fetched in a child node is bigger than you think. Also consider that data in every node is merged on the client within the parent. This is fast, but it also can take some time if you fetch massive amounts of entities. If you keep fetches small, you can use tuning parameters like the ParameterizedPrefetchPathThreshold setting to get more optimal queries. Deep inheritance hierarchies of type Target Per Entity/Type. If you use inheritance of type Target per Entity / Type (each type in the inheritance hierarchy is mapped onto its own table/view), fetches will join subtype- and supertype tables in many cases, which can lead to a lot of performance problems if the hierarchy has many types. With this problem, keep inheritance to a minimum if possible, or switch to a hierarchy of type Target Per Hierarchy, which means all entities in the inheritance hierarchy are mapped onto the same table/view. Of course this has its own set of drawbacks, but it's a compromise you might want to take. Fetching massive amounts of data by fetching large lists of entities. LLBLGen Pro supports paging (and limiting the # of rows returned), which is often key to process through large sets of data. Use paging on the RDBMS if possible (so a query is executed which returns only the rows in the page requested). When using paging in a web application, be sure that you switch server-side paging on on the datasourcecontrol used. In this case, paging on the grid alone is not enough: this can lead to fetching a lot of data which is then loaded into the grid and paged there. Keep note that analyzing queries for paging could lead to the false assumption that paging doesn't occur, e.g. when the query contains a field of type ntext/image/clob/blob and DISTINCT can't be applied while it should have (e.g. due to a join): the datareader will do DISTINCT filtering on the client. this is a little slower but it does perform paging functionality on the data-reader so it won't fetch all rows even if the query suggests it does. Fetch massive amounts of data because blob/clob/ntext/image fields aren't excluded. LLBLGen Pro supports field exclusion for queries. You can exclude fields (also in prefetch paths) per query to avoid fetching all fields of an entity, e.g. when you don't need them for the logic consuming the resultset. Excluding fields can greatly reduce the amount of time spend on data-transport across the network. Use this optimization if you see that there's a big difference between query execution time on the RDBMS and the time reported by the .NET profiler for the ExecuteReader method call. Doing client-side aggregates/scalar calculations by consuming a lot of data. If possible, try to formulate a scalar query or group by query using the projection system or GetScalar functionality of LLBLGen Pro to do data consumption on the RDBMS server. It's far more efficient to process data on the RDBMS server than to first load it all in memory, then traverse the data in-memory to calculate a value. Using .ToList() constructs inside linq queries. It might be you use .ToList() somewhere in a Linq query which makes the query be run partially in-memory. Example: var q = from c in metaData.Customers.ToList() where c.Country=="Norway" select c; This will actually fetch all customers in-memory and do an in-memory filtering, as the linq query is defined on an IEnumerable<T>, and not on the IQueryable<T>. Linq is nice, but it can often be a bit unclear where some parts of a Linq query might run. Fetching all entities to delete into memory first. To delete a set of entities it's rather inefficient to first fetch them all into memory and then delete them one by one. It's more efficient to execute a DELETE FROM ... WHERE query on the database directly to delete the entities in one go. LLBLGen Pro supports this feature, and so do some other O/R mappers. It's not always possible to do this operation in the context of an O/R mapper however: if an O/R mapper relies on a cache, these kind of operations are likely not supported because they make it impossible to track whether an entity is actually removed from the DB and thus can be removed from the cache. Fetching all entities to update with an expression into memory first. Similar to the previous point: it is more efficient to update a set of entities directly with a single UPDATE query using an expression instead of fetching the entities into memory first and then updating the entities in a loop, and afterwards saving them. It might however be a compromise you don't want to take as it is working around the idea of having an object graph in memory which is manipulated and instead makes the code fully aware there's a RDBMS somewhere. Conclusion Performance tuning is almost always about compromises and making choices. It's also about knowing where to look and how the systems in play behave and should behave. The four steps I provided should help you stay focused on the real problem and lead you towards the solution. Knowing how to optimally use the systems participating in your own code (.NET framework, O/R mapper, RDBMS, network/services) is key for success as well as knowing what's going on inside the application you built. I hope you'll find this guide useful in tracking down performance problems and dealing with them in a useful way.  

    Read the article

< Previous Page | 43 44 45 46 47 48 49 50 51 52 53 54  | Next Page >