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Adding validator controls to a form

From: ASP.NET Essential Training

Video: Adding validator controls to a form

Once you have modified a DetailsView control to use Template fields instead of Bound fields, you are then ready to add validator controls. Each validator control is bound to a single form control and each form control can be validated by one or more validators. You place the validator controls in the same Template fields that host the textboxes or other data entry form controls that the user interacts with to provide data. For this demonstration I'll work with the page named TitleInsertValidation.aspx. In this version of the page there are two Template fields.

Adding validator controls to a form

Once you have modified a DetailsView control to use Template fields instead of Bound fields, you are then ready to add validator controls. Each validator control is bound to a single form control and each form control can be validated by one or more validators. You place the validator controls in the same Template fields that host the textboxes or other data entry form controls that the user interacts with to provide data. For this demonstration I'll work with the page named TitleInsertValidation.aspx. In this version of the page there are two Template fields.

One for the Price and the other for the PubDate columns. They each have a TextBox control that allows user to type-in values but currently neither is validated. I'm going to show you how to add validator controls both in Design View and through code. I will start off in Design View. In Design View I'll select the DetailsView control. I'll open its Task list and select Edit Templates. I'll pull down the Template list and show you that there are two sets of templates for each of the two fields that are used in Template fields. Each Template field supports an ItemTemplate for displaying data, and AlternatingItemTemplate that allows you to setup say alternating background colors.

And then this one, the EditItemTemplate. The EditItemTemplate is the one that's used by default for either inserts or updates. I'll select that item for the Price field and I'll show you visually that it's showing the TextBox control that's already a part of the template. Now, I'll add the validator. I'll get out of Full Screen so I can see all of my panels. Then I'll go to the Toolbox panel. I'll move the cursor over the Toolbox tab and then pin the Toolbox panel into place. The validator controls are in a category labeled Validation. There are a number of validators you can choose from. I'm going to be using the RequiredFieldValidator and the RangeValidator.

The first one I'm going to implement will say that the price is required. I'll drag RequiredFieldValidator object and I'll place it inside the template. Then with the RequiredFieldValidator object selected, I'll go to the Properties panel. I'm going to double-click the Properties panel header to make it float, and then I'll drag it out so that it's wider and easier to read. There are two critical properties that you should set. First the ControlToValidate property gets set to the ID of the form control you want to validate. If you are working in the Properties panel, you can click into the ControlToValidate property and then pull down the list and you should see the only form control that's in the template. I'm selecting the Price field.

Then go to the ErrorMessage. The ErrorMessage defaults to the type of control, ReguiredFieldValidator, but it should be customized. And this is the error message that the user will see if they break the validator rules. I'll set the ErrorMessage to 'Price is required.' Now, I'll save the changes and let's see the behavior. I will run the page in the browser, and in the browser I'll simply click the Insert link in the DetailsView control. It's a little hard to see but the actual message Price is required is being displayed right under the control.

I'll show you how to fix the visual problems in just a moment. But let's add a couple of more validators. I'll close the Properties panel so I can return to Design View, and then I'll press Enter to move down to the next line and I'll also add a RangeValidator. A RangeValidator can be used to specify a particular data type: dates, numeric values and so on. And you can also set minimum and maximum values that the user is allowed to type-in. With the RangeValidator selected, I'll press the F4 key to bring back the Properties panel. I'll go to the ControlToValidate. I'll bind it to the same form control as before, price, and I'll set a different ErrorMessage.

This time the ErrorMessage is 'Price must be between 1 and 100.' Next, I'll implement the actual business rules. I'll scroll down a bit to the Type property and I'll set the Type to Double. Set it to Integer for whole numbers or Double for fractional numbers, such as a price. And then I'll set minimum and maximum values. I'll click into the MinimumValue and set it to 1, and the MaximumValue and set it to 100. I'll save my changes and I'll run the page again. And you will see a lot of extra space here. I'll show you how to fix that a little bit later, but now I'll simply click the Insert button and the message Price is required is displayed. And then I'll fill in a value that's non-numeric and click the Insert link again and this time I see the error message, Price must be between 1 and 100. So, that's how you setup the validators in Design View.

Now to do the same thing in Source View, if you prefer, I'll show that I'm going to go to Source View and then I'll press Alt+Shift+Enter to go to Full Screen and I'll locate the RangeValidator that I created for the price. I'll select the RangeValidator code and I'll copy it to the Clipboard. Then I'll go down to the Template field for the PubDate and I'll paste that code in the place within that template. Now I'm going to make changes to the RangeValidator that I just created. First I'll change the ID. It has to be unique within the page. I'll change it from RangeValidator1 to RangeValidator2. Then I'll set the ControlToValidate, changing it from price to pubdate. And I'll set the ErrorMessage to a value of 'Please enter a valid date.' When you use the RangeValidator to validate dates, the minimum and maximum values must be phrased as dates. I'll put in a broad range of dates, setting the MaximumValue to 12/31/2100, and the MinimumValue to 1/1/1900.

And here is the critical piece you must change. The Type attribute which was set to Double instead should be set to Date. So now I have another validator this time connected to the PubDate form control. When user fills in the form if they don't fill the control in with a well-formed date, this validator will trigger and it will show the error message that I specified. Because I didn't add a required validator for this textbox, the rule is that the user has to either enter a well-formed date or they can also leave it blank. I'll save the changes and run the page again.

And I'll click the Insert link and show that I'm only getting the message, Price is required. But now I'll click into the PubDate control and type a value that's not a date, such as the words 'not a date,' and click Insert. And now I also see the message, Please enter a valid date. Now as you can see there are some display issues that are implicit when you add these controls without applying formatting. But I'll show you how to deal with the formatting issues in a separate video.

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This video is part of

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ASP.NET Essential Training

79 video lessons · 49986 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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