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Customizing forms with item editing templates

From: ASP.NET Essential Training

Video: Customizing forms with item editing templates

In ASP.NET websites that include data entry forms it's useful to be able to validate form entry. When user's type values into data entry forms, you can use ASP.NET validator controls that are bound to the data entry form controls. You can then set custom rules on these validator controls and cause error messages to be displayed without extensive programming. For the demonstrations in this chapter, I'll use a website that's part of the exercise files. If you have access to the exercise files, select File > Open Web site. Go to the Validation folder under Ch09Validation and open it. Then open the file TitleInsert.aspx.

Customizing forms with item editing templates

In ASP.NET websites that include data entry forms it's useful to be able to validate form entry. When user's type values into data entry forms, you can use ASP.NET validator controls that are bound to the data entry form controls. You can then set custom rules on these validator controls and cause error messages to be displayed without extensive programming. For the demonstrations in this chapter, I'll use a website that's part of the exercise files. If you have access to the exercise files, select File > Open Web site. Go to the Validation folder under Ch09Validation and open it. Then open the file TitleInsert.aspx.

In the starting version of this page, there is a Details View control that's bound to an SqlDataSource. There are four fields that are being accepted in the form right now, the Title, Price, Publication Date, and Notes. I will run the page in the browser and I'll type some values into the controls and show you what can go wrong. I'll click into the Title and type any value, 'A title,' and then I'll type a nonnumeric value in as the price, just xyz. And I'll do the same thing for the PubDate and I'll click the Insert link. And in response I get a server error.

The key error here is at the top. There was an attempt to take a string and format it as a number, and because I, as the user didn't type-in a numeric value, the page fails. So to prevent that issue from happening, we need to capture the problem before the data is sent to the server. In web environments, validation is handled in two possible ways either with client-side validation or server-side validation. In server-side validation, data is sent to the server and then logic is applied to the data at the server level, and then if there is a problem, an error message is sent back to the webpage where its refreshed.

In client-side validation, the validation logic is handled entirely by the client. That's the kind of validation that's used in ASP.NET. Before you can apply validators in a DetailsView control, you first have to replace any instances of the BoundField component with Template fields. A Template field allows you to apply your own specific controls including textboxes, pull-down lists, and most importantly here the validator controls. I will prepare the form for validation like this. I'll select the DetailsView control, then I'll open the Task list and select Edit Fields. I'm going to validate two controls, the Price and the Publication Date. First, I'll click on the Price and the Selected fields list and I'll delete it. And then I'll do the same thing for the PubDate.

Now I'll add two Template fields. I'll go to the Available field list at the top. I'll choose TemplateField and click Add. For the first template field, I'll then go to HeaderText and put in the old HeaderText for the Price field of Price. Then I'll click on the item again and click the Up Arrow a couple of times to move it back up into place. Then I'll do the same thing for the PubDate. I'll add a new TemplateField, I'll set its HeaderText to match the old one and then I'll move it back up into place. So that my selected fields are in the same order, then I'll click OK.

You will see in the DetailsView control presented in Design View that there are no longer textboxes in the data entry form. I have to replace those now with explicit templating. So the next step is to go into Source View and start to code. I will click on the Source button and then press Alt+Shift+Enter to go into full screen, and then I'll locate my new TemplateFields. Here is the first one. Notice that the TemplateField is created with a pair of tags. Place the cursor between the tags and press Enter a couple of times to make some space. Within the TemplateField, I'll declare an EditItemTemplate as a pair of tags. This is the template that will be presented when the Details View control is in Edit mode.

Now within the EditItemTemplate, I'll declare an asp: TextBox. I'll give it an ID matching the ID of the old BoundField, and also matching the name of the database column on the server, price, I'll put in the essential runat = "server" attribute. And then just in case this form is going to be used to present existing data, I'll add a Text attribute and I'll use this binding expression. I'll start off with the less than and a percent and then within the tokens of pound sign and then I call to the Bind function. And within the Bind function I'll pass in the name of the database column, price. Finally, at the end of the textbox, I'll close the tag.

Now I'll save and run the page again. I'll select Debug > Start Without Debugging and when the data entry form opens, I'll see my new textbox which is a part of the editing template. Now I'll go back to the code and do the same thing for the Publication Date. I'll select the EditItemTemplate that I created for the price and then I'll copy that to the Clipboard. The code will be almost exactly the same for the PubDate. I'll click into the tags for the TemplateField for the PubDate, then I'll go to the new version of the TextBox control and I'll set both the ID and the database column name in the Bind function to the original name of the column PubDate.

Now I'll save and fully test the page. I'll press Ctrl+S to save and then run the page, and then I'll type-in some values. The title will be My New Book, I'll type-in a numeric value this time, a 15, a well-formed date of 3/1/2009 and Some Notes. Then I'll click the Insert link. You will see that the form is simply refreshed with new blank values. Now I'll go to the Database Explorer, I'll go back to Visual Web Developer and exit Full Screen. Go to the Database Explorer, open the Tables list, right-click on the Titles table and select Show Table Data, scroll down to the bottom of the data and show that my new record was successfully inserted.

So all this is in preparation for validation. Before you can apply validator controls to a data entry form that's presented within a Details View component, you must modify your Details View to use the TemplateField instead of the BoundField for any control that you want to validate.

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This video is part of

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ASP.NET Essential Training

79 video lessons · 49158 viewers

David Gassner
Author

 
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  1. 18m 44s
    1. Welcome
      1m 42s
    2. Prerequisites
      2m 21s
    3. Using the exercise files
      1m 32s
    4. Upgrading exercise file websites for ASP.NET 4.5 (NEW)
      2m 40s
    5. What's new in ASP.NET 4 (NEW)
      3m 48s
    6. What's new in ASP.NET 4.5 (NEW)
      3m 23s
    7. What's new in this course update (NEW)
      3m 18s
  2. 33m 34s
    1. Understanding how ASP.NET works
      5m 52s
    2. Installing Microsoft Visual Web Developer 2008
      3m 43s
    3. Installing Visual Studio Express 2012 for web (NEW)
      2m 12s
    4. Hello World: Creating your first ASP.NET web site
      4m 28s
    5. Creating pages with dynamic output
      7m 39s
    6. Understanding the development web server
      4m 49s
    7. Exploring the development environment
      4m 51s
  3. 40m 2s
    1. Understanding Microsoft SQL Server
      5m 47s
    2. Installing SQL Server Express
      6m 51s
    3. Exploring SQL Server Management Studio Basic
      4m 23s
    4. Creating a new database
      8m 51s
    5. Connecting to the database in ASP.NET
      5m 35s
    6. Testing SQL queries
      3m 53s
    7. Presenting a dataset in an ASP.NET page
      4m 42s
  4. 25m 31s
    1. Understanding ASP.NET web form pages
      5m 51s
    2. Separating presentation and logic with code files
      4m 17s
    3. Adding web form controls to a page
      5m 25s
    4. Handling postback data in a web form page
      5m 50s
    5. Using data binding expressions
      4m 8s
  5. 48m 37s
    1. Creating a testing environment
      4m 40s
    2. Declaring and using a simple variable
      6m 14s
    3. Declaring and using a complex object
      6m 16s
    4. Using loops
      6m 52s
    5. Using functions
      9m 25s
    6. Using trace statements
      4m 47s
    7. Debugging with breakpoints
      5m 45s
    8. Commenting code
      4m 38s
  6. 17m 43s
    1. Creating web controls
      5m 53s
    2. Registering a user control on a web form page
      3m 25s
    3. Registering controls globally in the web.config file
      3m 53s
    4. Adding public properties to a web control
      4m 32s
  7. 19m 7s
    1. Understanding Cascading Style Sheets (CSS)
      5m 36s
    2. Attaching external CSS files
      3m 12s
    3. Defining a CSS selector
      6m 10s
    4. Using CSS class selectors in server controls
      4m 9s
  8. 30m 34s
    1. Presenting data with the GridView control
      5m 49s
    2. Controlling GridView paging and appearance
      5m 46s
    3. Editing data with the GridView control
      6m 57s
    4. Presenting data with the DataList control
      5m 42s
    5. Formatting data with binding expressions
      6m 20s
  9. 36m 46s
    1. Using the DetailsView control
      7m 33s
    2. Inserting data with the DetailsView control
      6m 36s
    3. Redirecting page requests
      9m 39s
    4. Creating an update page
      6m 20s
    5. Linking to update pages from the list page
      4m 3s
    6. Deleting database records
      2m 35s
  10. 22m 15s
    1. Customizing forms with item editing templates
      6m 7s
    2. Adding validator controls to a form
      6m 40s
    3. Controlling the validation error message display
      6m 24s
    4. Using the ValidationSummary control
      3m 4s
  11. 29m 49s
    1. Creating a query with joined tables
      8m 6s
    2. Replacing control style properties with CSS
      5m 50s
    3. Creating a CSS file for printing
      3m 14s
    4. Suppressing elements in printed web pages
      5m 47s
    5. Selecting data for a report
      6m 52s
  12. 11m 14s
    1. Understanding ViewState and managing postbacks
      4m 36s
    2. Using session variables
      6m 38s
  13. 20m 57s
    1. Turning on forms authentication
      1m 51s
    2. Creating a page to log in users
      4m 18s
    3. Creating a page to set up new users
      4m 6s
    4. Understanding the security database
      3m 27s
    5. Configuring security in the web.config file
      2m 59s
    6. Creating a page to log out users
      4m 16s
  14. 27m 56s
    1. Installing IIS on Windows XP
      6m 32s
    2. Installing ASP.NET 3.5 on Windows XP
      1m 39s
    3. Deploying a site on Windows XP
      5m 9s
    4. Installing Information Internet Services (IIS) on Windows Vista, Windows 7, and Windows 8
      1m 56s
    5. Configuring ASP.NET 3.5 on Windows Vista
      2m 15s
    6. Deploying an application on Windows Vista
      3m 29s
    7. Scripting a database for deployment
      3m 36s
    8. Exporting database scripts in SQL Server Management Studio 2012 (NEW)
      3m 20s
  15. 2m 0s
    1. Where to go from here
      2m 0s

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