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Controlling the validation error message display

From: ASP.NET Essential Training

Video: Controlling the validation error message display

When you place an ASP.NET Validator control within a DetailsView control, its formatting is controlled by the Container control. That is, the DetailsView. And it's a good idea to apply formatting to the validator to make sure that it stands out and the user sees it clearly. For this demonstration, I'll be working in the file TitleInsertValidationMessages.aspx. In this file I have created a number of validators and applied them to the various form controls, the Price and PubDate. I will start by running the page in the browser and show you the nature of the problem. The DetailsView control that contains both the form controls and the validators has a particular background color. I'll leave the Price blank and type in a non-date value into the PubDate control. And then I'll click the Insert link, and you will see that the error messages using their default formatting are hard to read against the background of the Details View.

Controlling the validation error message display

When you place an ASP.NET Validator control within a DetailsView control, its formatting is controlled by the Container control. That is, the DetailsView. And it's a good idea to apply formatting to the validator to make sure that it stands out and the user sees it clearly. For this demonstration, I'll be working in the file TitleInsertValidationMessages.aspx. In this file I have created a number of validators and applied them to the various form controls, the Price and PubDate. I will start by running the page in the browser and show you the nature of the problem. The DetailsView control that contains both the form controls and the validators has a particular background color. I'll leave the Price blank and type in a non-date value into the PubDate control. And then I'll click the Insert link, and you will see that the error messages using their default formatting are hard to read against the background of the Details View.

You will also see that there is a bunch of extra space between the error messages and the controls themselves. That's because with their current settings, the validation controls reserves space for the area that's going to be needed to display the messages. It's possible to make this more dynamic so that the controls only appear and the form only makes adequate space for the messages when an error condition exists. So I'll correct both of those issues. First, I'll deal with the space issue. Each of the validators has a property called Display. When I drag to the controls in Design View, the Display wasn't set, but it defaults to something called Static. That means that when the form is initially presented, it reserves the space that might be needed for an error. Here is how we can fix that.

I will go to the first validator. The RequiredFieldValidator for the Price control and I'll add a Display property and I'll set it to a value of Dynamic. Now, I'll copy that setting and then I'll paste it into each of the other validators. I will select Display="Dynamic", and press Ctrl+C to copy. Then I'll go to the RangeValidator for the price and paste it in. And I'll do the same for the RangeValidator for the PubDate control. Right around line 32 of the file there is a break tag between the two validators. You will only see one validator at a time. Either the RequiredFieldValidator's message or the RangeValidator's. You won't be showing both messages simultaneously, so the break tag can go away. And now watch what happens when I run the page.

And you will see that extra space has been eliminated. Then I'll click the Insert link and you will see that the form presentation is modified dynamically to make room for the error message. And if I type-in a non-date value into the PubDate and click Insert again, once again you will see that the space is allocated as needed. So that's the result of setting the property Display to a value of Dynamic. Next I'll deal with the formatting issues. It's possible to apply individual formatting options to each control. Let's take the RequiredFieldValidator as an example. I'll place the cursor inside the RequiredFieldValidator tag.

I'll press Enter and I'll set a property called BackColor, and I'll select a color of #EEEEEE, which is a light gray. I'll save the change and run the page. And then I'll click the Insert link and you will see that the error message is now very easy to read. The problem with this approach though is that you will need to apply that same setting to each individual Validator control not just in this page but throughout your website. It's a lot better to create a single set of rules and then apply them to all validators. And once again this is where Cascading Style Sheets can help. I'll solve this problem by creating a single CSS class and then I'll tell each Validator control to use that class by setting its CSS Class property.

Now I'll do a little bit of Cascading Style Sheet work. I'll go the Solution Explorer and locate the file styles. css and double-click it to open it. Now I'll go to the CSS Outline panel that appears automatically. I'll right-click and select Add Style Rule. I'm going to be defining a class. So, I'll select the Class name, click into the input, and I'll name my new CSS Class validationError, and then I'll click OK. That creates the Validation Error class declaration.

From here I can either work in the CSS dialog box, or I can just do the code. I know what the code should be, so I'll just type it in. I'll put in background-color, and set it to a value of #EEEEEE. Be sure if you are typing this from scratch that you include the pound sign before the six character color value. And then I can also set also Cascading Style Sheet properties. For example I'll set the font-weight to a value of bold. So that class is now available to all pages in my website because the style. css file is linked into each of these pages. I'll save the changes, and then I'll go back to the page titled InsertValidationMessages.aspx.

I will go to the RequiredFieldValidator and I'll remove the BackColor setting and instead I'll put in CssClass= and then I'll select the class name ValidationError, which shows up automatically in Visual Web Developer because it's constantly monitoring the contents of the styles.css file that's linked into this page. Now I'll select that declaration of CssClass and press Ctrl+C to copy it to the Clipboard and I'll go to each of the two RangeValidators and paste it in.

I'll save those changes and run the page again. I'll once again leave the Price blank and I'll type-in a non-date value in the PubDate to trigger its validation. And I'll click Insert a couple of times and you will see that both validation error messages are displayed and they both have the same background color and the same bold font. So that's how you can centralize the formatting of your error messages. So in this video I have described how to cause the validation objects to only allocate space dynamically, when the space is needed. And I have also described how to define and use common formatting for all Validator objects using Cascading Style Sheet classes and the CSS Class property.

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This video is part of

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ASP.NET Essential Training

79 video lessons · 48737 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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