Validating dropdownlist in 2 0, 33 replies
Figure 42 That's all there is to it! Because we have not implemented any validation within the application, though, nothing prevents us from entering bogus input within the form and posting it to the server.
You can learn more about how to localize validation error messages here. This is done via the last line of code in the code snippet above. This means that enabling validation is really easy for common application scenarios, while at the same time still remaining very flexible for more advanced ones.
When we add these three lines, ASP. In this section we'll look at two examples of customizing the GridView's editing interface.
Above is a screen-shot that shows a Person class defined using the ADO.
When our HTML form is posted back to the server, the above method will be called. You can also optionally define your own custom validation attributes and use them as well.
Looking back at Validating dropdownlist in 2 0 last two editable GridView examples, consider what would happen if the user entered a value of, say, Sam for the Unit Price of a product.
IsValid check within our code will return true — in which case we will eventually save the Person to a database and then redirect back to the home-page.
As part of this process, it will also check to see whether the DataAnnotation validation attributes for the Person object are valid.
In the first, we'll see how to add validation controls; in the second, we'll look at replacing the standard TextBox with a DropDownList instead.
This example demonstrates the GridView's default editing interface, which renders all editable columns as TextBoxes. This will help ensure that we keep our code DRY and avoid repeating rules in multiple places. We'll look at the required signature for the Update method and see how to configure the ObjectDataSource to use this method.
This ability to specify the validation rules one place and have it be honored and respected everywhere allows us to rapidly evolve our application and rules with a minimum amount of effort and keep our code very DRY.
These can be safely removed if you are creating a GridView that's limited to just editing the existing data.
The benefit of implementing the rules within our Person object is that this will ensure that the validation will be enforced via any scenario within our application that uses the Person object for example: Regardless of how you want to alter the GridView's editing interface, the way it's accomplished is through using TemplateFields as opposed to BoundFields.
Alternatively, you can choose to derive from any of the existing validation attributes if you want to simply extend their base functionality.
Our next task is to customize the editing interface for the CategoryName column so that it uses a DropDownList of categories as opposed to a TextBox.
Additionally, the standard TextBox as an editing interface might not be acceptable; we'll also look at an example that replaces the TextBox with a databound DropDownList. When the end user clicks on an Edit button that Dating website chat free becomes editable, causing the Edit button to change to Update and Cancel buttons and the other columns to become TextBoxes.
Figure 47 shows a screenshot of the GridView as it's being edited.