Integrated development environments (IDEs) provide tools for debugging code by setting breakpoints in the code to inspect the state of the application during processing. In web app development, we can inspect our app using the developer tools available in our web broswers.

Chrome

View ⇨ Developer ⇨ Developer Tools

Firefox

Tools ⇨ Browser Tools ⇨ Web Developer Tools

Safari

Develop ⇨ Show Web Inspector

Edge

Right click ⇨ Inspect

Validate that data entered into a web form matches expectations. Validation provides assurances around:

• App Security
• App Functionality
• Data Accuracy

Validation can occur on the front-end using Javascript, the back-end on the web server, or both.

• Types of Validation
• Required vs optional fields
• Type of data accepted
• Length of data string
• Valid character set
• Numeric range
• Specific format (matching regex)

In ASP.net MVC Core we can use Data Annotations: Implemented by

1. Adding namespace
   using System.ComponentModel.DataAnnotations;
2. Annotating class property declarations with one or more constraints. Some examples include:
   [Required(ErrorMessage = "")]
[Range(n, m, ErrorMessage = "")]
[StringLength(n, ErrorMessage = "")]
3. An example using 2 constraints from the MVC Tutorial
   [Required(ErrorMessage = "An Album Title is required")]
[StringLength(160)]
public string Title { get; set; }