This content originally appeared on DEV Community and was authored by kevin walker
When building a web app, data validation is an essential step. By checking if the data submitted is complete and correct, it secures the system. Web developers can create high-quality, dynamic websites with the help of ASP.NET. Data entered by the user must not be invalid, unauthenticated, or conflicting; this is where ASP.NET validation controls come in. It allows the web application to validate user input before processing it, making sure it is accurate and legitimate. To rephrase, developers can use ASP.NET validation controls to check user input before sending it to the server. This will allow them to manage the collected data and ensure it satisfies all specifications.
This article will go over the various ASP.NET validation control categories, how they work, and how to use them effectively in your online application. Each of the various types of validation controls has a specific function when it comes to checking user input. They have a wide range of potential applications, including the validation of dates, figures, email messages, and strings.
Upon finishing this post, you shall have the necessary information and skills to enhance the integrity of your application. And the validation controls that are put in place improve the user experience.
The ASP.NET Validation Control: How Does It Function?
When it comes to validating user input in online applications, Microsoft’s ASP.NET provides robust and versatile control mechanisms. These checks ensure that the data is accurate and conforms to the standards established by developers at various levels of the app automatically, both on the server and on the client.
After a user submits data via a web form, the ASP.NET validation control verifies the data by comparing it to predefined validation criteria. There will be an error message shown if the validation requirements are not satisfied. This happens locally on the user’s device in order to enhance their experience and decrease server round-trips.
After that, the data is sent to the server, where validation happens on the server side. Now, the server-side code to validate user input is generated by the ASP.NET validation controls. To prevent a malicious user from quickly circumventing client-side control by manipulating scripts, this is essential.
In addition, ASP.NET has a cross-page validation control, which is useful for situations where one page validates user input and another page displays the outcomes. Developers may verify user input across various application pages with cross-page validation.
Types of ASP.NET Validation Controls
Developers get to try a variety of sophisticated tools tailored to their individual validation demands thanks to ASP.Net’s many validation controls. The six various types of validation controls in the ASP.NET together with their general syntax, are listed below.
1. RequiredFieldValidator Control
To determine if user input is null or unfilled, programmers may implement the RequiredFieldValidator, a fundamental validation control in ASP.NET. Required information, such as identity, email, and phone number, can be validated using this tool. To guarantee reliable data collection, the RequiredFieldValidator is a crucial tool. And to avoid exceptions caused by null references while processing the data that follows. You won’t have any trouble using the RequiredFieldValidator control compared to others. To do this, you must define the tool to be used for validation by setting the ControlToValidate property.
Generic syntax:
<asp:RequiredFieldValidator ID="someUniqueId"
runat="server" ControlToValidate ="someUniqueControlId"
ErrorMessage="ErrorToDisplayOnValidationFailure"
InitialValue="aPlaceholderValue">
</asp:RequiredFieldValidator>
2. CompareValidator Control
In order to assess the user’s input in different fields, CampareValidator control is useful. Mailing details, login credentials, and other data that ought to appear across fields are compared using the CampareValidator control. It also helps in making sure data is consistent and intact. The ControlToCompare property must be specified in order to run this control.
Generic syntax:
<asp:CompareValidator ID="someUniqueId"
runat="server" ControlToValidate ="someUniqueControlId"
ErrorMessage="ErrorToDisplayOnValidationFailure"
Type="string" ControlToCompare=”ControlToValidateIdOfAnotherControl”
ValueToCompare=”aFixedValue” Operator=”Equal”>
</asp:CompareValidator>
3. RangeValidator Control
When validating user input, such as a birthday or an amount of money, developers utilize the RangeValidator control to determine if the value is inside a specified range. Developers can prevent false data from reaching the database by using this ASP.NET control. This strengthens the data’s reliability and accuracy across the web app.
With the MinimumValue and MaximumValue attributes, you are required to set the lowest and highest values for the RangeValidator control. Moreover, programmers may determine the information type of the input field using the Type property. This property supports String, Integer, and Double.
Generic syntax:
<asp:RangeValidator ID="some unique id"
runat="server" ControlToValidate ="someUniqueControlId"
ErrorMessage="ErrorToDisplayOnValidationFailure"
Type="Integer" MinimumValue=”0” MaximumValue=”100”>
</asp:RangeValidator>
4. RegularExpressionValidator Control
Regex, an ASP.NET RegularExpressionValidator control, lets programmers check if user input follows a certain format. In cases when several user inputs are required, such as when entering an area code, email address, or mobile number, this is of the utmost importance to avoid mistakes in the steps that come after.
Regex also has the ability to give consumers instant feedback as they input data, which streamlines the form-filling process and enhances the user experience. The ValidationExpression property specifies a pattern that is used to validate the input text.
Generic syntax:
<asp:RegularExpressionValidator ID="someUniqueId"
runat="server" ControlToValidate ="someUniqueControlId"
ErrorMessage="ErrorToDisplayOnValidationFailure"
ValidationExpression=”aRegexPattern”>
</asp:RegularExpressionValidator>
5. CustomValidator Control
To make the validation code work with their own user components, programmers may utilize the CustomValidator control. This is most helpful when the built-in controls do not meet the programmers’ requirements for specialized business logic in validation.
Validation can be performed on both the client and server sides via this control. Nevertheless, many opt for the more capable server-side technique. To determine which control to validate and which method to apply for validation logic, the CustomValidator control makes use of the ClientValidationFunction and ServerValidate attributes.
Generic syntax:
<asp:CustomValidator ID="someUniqueId"
runat="server" ControlToValidate ="someUniqueControlId"
ErrorMessage="ErrorToDisplayOnValidationFailure"
ClientValidationFunction=”functionName”>
</asp:CustomValidator>
6. Validation Summary Control
One useful ASP.NET feature that could potentially be used to summarize form submission problems is the ValidationSummary control. A bulleted list or a detailed description accompanied by summary text are two possible formats for this.
Developers can optimize the user experience and personalize the complete layout with this control’s array of settings, including HeaderText, DisplayMode, and CssClass. Set the ShowMessageBox property to True to display a message box with errors. This can help you identify and restore them.
Generic syntax:
<asp:ValidationSummary ID="ValidationSummaryControl"
runat="server" DisplayMode=”BulletList” ShowSummary=”true”
HeaderText=”List of Errors” />
Final Words
The ASP.NET validation controls are introduced in this post. As you begin to construct your online form, you will find that there is much more to learn. Web application programmers who prioritize user security and reliability have ASP.NET validation controls at their disposal. These controls are both versatile and critical. These controls facilitate effective data management and give simple and brief error feedback via their adjustable properties and easy deployment.
This content originally appeared on DEV Community and was authored by kevin walker