F9 Group Marketing and Technology Blog

The .NET Framework provides a variety of classes in the System.IO namespace that simplify working with the file system. Using these classes it’s possible to delete files and folders, to create new files, to edit existing files, and more. These classes, combined with ASP.NET’s suite of Web controls and databinding syntax, make it quite easy to present information about the files on the web server’s file system to visitors to your website. With a bit of markup and code, it’s possible to add a simple file browser to a web page that allows users to view the files and folders from a particular directory on the web server. Such file browsers are useful if you let users upload content to the website and need to let them view their uploaded content. If you have a folder that contains user-accessible content like images, PDF files and Word documents, a file browser offers a quick and easy way for users to see what content is available and to view content of interest. Back in 2003 I wrote an article titled Displaying the Files in a Directory using a DataGrid that showed how to list the files of a particular folder in a DataGrid Web control. This dated article still attracts a decent amount of traffic and questions from readers, so much so that I thought it worthwhile to update the content to use the latest technology, namely ASP.NET 4 and the GridView Web control. I also added some new features. For example, the file browser now lists both files and folders, allowing users to view the files in subfolders. Also, I moved the markup and code into a User Control, which simplifies adding the file browser to an ASP.NET page.

Last week’s article, Implementing the Store Locator Application Using ASP.NET MVC (Part 1) , started a two-part article series that walked through converting my ASP.NET store locator application from WebForms to ASP.NET MVC. Last week’s article stepped through the first tasks in porting the store locator application to ASP.NET MVC, including: creating the new project; copying over stylesheets, the database, scripts, and other shared content from the WebForms application; building the HomeController ; and coding the Index and StoreLocator actions and views. Recall that the StoreLocator action and view prompts the user to enter an address for which to find nearby stores. On form submission, the action interfaces with the Google Maps API ’s geocoding service to determine if the entered address corresponds to known latitude and longitude coordinates. If so, the user is redirected to the StoreLocatorResults action (which we create in this article) that displays the nearby stores in both a grid and as markers on a map. Unlike the StoreLocator action created in Part 1, the StoreLocatorResults action uses a more intricate model and a strongly-typed view. Read on to learn more! Read More >

Back in May 2010 I wrote a three-part article series titled Building a Store Locator ASP.NET Application Using Google Maps API , which showed how to build a simple store locator application using ASP.NET and the Google Maps API. The application consisted of two ASP.NET pages. In the first page, the user was prompted to enter an address, city, or postal code ( screen shot ). On postback, the user-entered address was fed into the Google Maps API’s geocoding service to determine whether the address, as entered, corresponded to known latitude and longitude coordinates. If it did, the user was redirected to the second page with the address information passed through the querystring. This page then queried the database to find nearby stores and listed them in a grid and as markers on a map ( screen shot ). Since the WebForms store locator application was published, several readers have emailed me to ask for an ASP.NET MVC version. I recently decided to port the existing WebForms application to ASP.NET MVC. This article, the first in a two-part series, walks through creating the ASP.NET MVC version of the store locator application and pinpoints some of the more interesting and challenging aspects. This article examines creating the ASP.NET MVC application and building the functionality for the user to enter an address from which to find nearby stores. Part 2 will examine how to show a grid and map of the nearby stores. Read on to learn more! Read More >

One of the new controls available with ASP.NET 4 is the QueryExtender control. The QueryExtender is designed to simplify filtering data returned from a LinqDataSource or EntityDataSource by decoupling the filtering logic from the data source control. Using the QueryExtender is easy – simply add a QueryExtender to the page, specify what data source control it applies to, and then define the filtering criteria. For example, when displaying product information on a web page you could use the QueryExtender control and a few lines of markup to display only those products that are not within a certain price range and whose name or category starts with a user-specified search string. Filtering the data returned by a LinqDataSource or EntityDataSource control is certainly possible without the QueryExtender; both the LinqDataSource and EntityDataSource controls have a Where property that can be used to specify filtering criteria. What the QueryExtender offers is a simpler means by which to filter data. This article includes a number of demos (which can be downloaded at the end of this article) that showcase the QueryExtender’s ease of use and its powerful filtering capabilities. Read on to learn more! Read More >

An enumeration is a special type in the .NET Framework that is comprised of a number of named constants. While you might not have created an enumeration type yourself, you have likely used enumerations many times in day-to-day programming. For example, the rows in a GridView have a RowType property that returns an enumeration of type DataControlRowType that indicates the row’s type: Header , Footer , DataRow , and so on. When working with an enumeration we may need to display a descriptive message based on the enumeration’s value. For example, using ASP.NET’s Membership system you can programmatically create a new user account calling the Membership class ’s CreateUser method . This method specifies the success or failure of the operation via the MembershipCreateStatus enumeration . This enumeration has members like Success , InvalidUserName , InvalidPassword , DuplicateUserName , and the like. When calling this method from an ASP.NET page you might want to show the user a descriptive message based on this enumeration value. This article explores three different ways to provide descriptive text for enumeration members. Read on to learn more! Read More >

Chances are, there are several different URLs that point to the same content on your website. For example, the URLs http:// yoursite .com , http:// yoursite .com/default.aspx , http://www. yoursite .com , or http://www. yoursite .com/default.aspx are all likely valid URLs that results in the same content, namely the homepage for yoursite .com . While having four different URLs reference the same content may not seem like a big deal, it can directly impact your website’s search engine placement and, consequently, it’s traffic. To a search engine, those four different URLs represent four different pages, even though the all produce the same content. To understand how allowing duplicate URLs in your website can affect your search engine placement, first understand that search engines base a page’s placement in the search results based, in part, on how many other websites link to the page. Now, imagine that there are 1,000 web pages from other websites that link to your homepage. You might conclude, then, that a search engine would rank the importance of your homepage based on those 1,000 links.

The ASP.NET Web Forms model strives to encapsulate the lower level complexities involved in building a web application. Features like server-side event handlers, the page lifecycle, and view state effectively blur the line between the client and the server, simplify state management, and free the developer from worrying about HTTP, requests and responses, and similar matters. While these facets of the Web Forms model allow for rapid application development and make ASP.NET more accessible to developers with a web application background, their behavior can impact your website’s behavior and performance. View state is perhaps the most important – yet most misunderstood – feature of the Web Forms model. In a nutshell, view state is a technique that automatically persists programmatic changes to the Web controls on a page.

One of the most sure-fire ways to improve a web application’s performance is to employ caching. Caching takes some expensive operation and stores its results in a quickly accessible location. Since it’s inception, ASP.NET has offered two flavors of caching: Output Caching – caches the entire rendered markup of an ASP.NET page or User Control for a specified duration. Data Caching – a API for caching objects. Using the data cache you can write code to add, remove, and retrieve items from the cache. Until recently, the underlying functionality of these two caching mechanisms was fixed – both cached data in the web server’s memory. This has its drawbacks. In some cases, developers may want to save output cache content to disk. When using the data cache you may want to cache items to the cloud or to a distributed caching architecture like memcached .

Many websites that support user accounts require users to enter an email address as part of the registration process. This email address is then used as the primary communication channel with the user. For instance, if the user forgets her password a new one can be generated and emailed to the address on file. But what if, when registering, a user enters an incorrect email address? Perhaps the user meant to enter me@example.com , but accidentally transposed the first two letters, entering em@example.com . How can such typos be prevented? The only foolproof way to ensure that the user’s entered email address is valid is to send them a validation email upon registering that includes a link that, when visited, activates their account.

Last week’s article, Building a Store Locator ASP.NET Application Using Google Maps API (Part 1) , was the first in a multi-part article series exploring how to add store locator-type functionality to your ASP.NET website using the free Google Maps API . Part 1 started with an examination of the database used to power the store locator, which contains a single table named Stores with columns capturing the store number, its address and its latitude and longitude coordinates. Next, we looked at using Google Maps API’s geocoding service to translate a user-entered address, such as San Diego, CA or 92101 into its latitude and longitude coordinates. Knowing the coordinates of the address entered by the user, we then looked at writing a SQL query to return those stores within (roughly) 15 miles of the user-entered address.