How to implement client-side and server-side validation for teacher updates in ASP.NET MVC?

I’m working on a school management system (ASP.NET MVC + MySQL) and need to implement update functionality for teacher records with robust validation. Here’s where I’m stuck:

Current Implementation

1. Server-Side (API Controller)

   [HttpPut]
   [Route("api/TeacherPage/UpdateTeacher")]
   public IHttpActionResult UpdateTeacher([FromBody] Teacher teacher)
   {
       // Manual validation
       if (string.IsNullOrEmpty(teacher.TeacherFname))
           return BadRequest("Teacher name is required.");
   
       if (teacher.HireDate > DateTime.Now)
           return BadRequest("Hire date cannot be in the future.");
   
       // ... database update logic
   }
   

2. Client-Side (Edit.cshtml)

   @model Teacher
   
       
       
       
   
   
   
   

Specific Problems

1. Validation Duplication: I’m repeating checks (e.g., empty name) on both client and server. Is there a way to centralize validation rules (e.g., using [Required] annotations)?
2. Error Handling: My AJAX call doesn’t show server validation errors (e.g., "Hire date invalid"). How can I display these errors in the form?
3. Partial Updates: Should I use PUT (full updates) or PATCH (partial updates) for better REST compliance?

What I’ve Tried

• Added [Required] to Teacher.cs properties, but client-side validation doesn’t trigger for AJAX.
• Used ModelState.IsValid in the controller, but it’s always true for JSON payloads.

Environment:

• ASP.NET MVC 5
• jQuery 3.6
• MySQL