Data Transfer in ASP.NET Core MVC Controllers with TempData

In ASP.NET Core MVC, you can pass temporary data from one controller to another using TempData. TempData is a dictionary that can be used to share data between controllers during the current request and the subsequent redirect. Here's how you can achieve this.

Set TempData in the First Controller

In your first controller action, set the TempData with the data you want to pass.

[HttpPost]
[ValidateAntiForgeryToken]
public async Task<IActionResult> Create(Student student)
{
    if (ModelState.IsValid)
    {
        _context.Add(student);
        await _context.SaveChangesAsync();
        return RedirectToAction(nameof(Index));
    }
    // Transfer the Complete Student Object to the Teacher
    TempData["student"] = student;
    return RedirectToAction("Index","Teacher");
}

Complete Student Controller Code

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.Mvc.Rendering;
using Microsoft.EntityFrameworkCore;
using DataTransferBetweenControllersinASPNETCoreMVC.DatbaseContext;
using DataTransferBetweenControllersinASPNETCoreMVC.Models;

namespace DataTransferBetweenControllersinASPNETCoreMVC.Controllers
{
    public class StudentsController : Controller
    {
        private readonly AppDbContext _context;

        public StudentsController(AppDbContext context)
        {
            _context = context;
        }

        // GET: Students
        public async Task<IActionResult> Index()
        {
            return View(await _context.Students.ToListAsync());
        }

        // GET: Students/Details/5
        public async Task<IActionResult> Details(int? id)
        {
            if (id == null)
            {
                return NotFound();
            }

            var student = await _context.Students
                .FirstOrDefaultAsync(m => m.Id == id);
            if (student == null)
            {
                return NotFound();
            }

            return View(student);
        }

        // GET: Students/Create
        public IActionResult Create()
        {
            return View();
        }

        // POST: Students/Create
        // To protect from overposting attacks, enable the specific properties you want to bind to.
        // For more details, see http://go.microsoft.com/fwlink/?LinkId=317598.
        [HttpPost]
        [ValidateAntiForgeryToken]
        public async Task<IActionResult> Create(Student student)
        {
            if (ModelState.IsValid)
            {
                _context.Add(student);
                await _context.SaveChangesAsync();
                return RedirectToAction(nameof(Index));
            }
            // Transfer the Complete Student Object to Teacher
            TempData["student"] = student;
            return RedirectToAction("Index","Teacher");
        }

        // GET: Students/Edit/5
        public async Task<IActionResult> Edit(int? id)
        {
            if (id == null)
            {
                return NotFound();
            }

            var student = await _context.Students.FindAsync(id);
            if (student == null)
            {
                return NotFound();
            }
            return View(student);
        }

        // POST: Students/Edit/5
        // To protect from overposting attacks, enable the specific properties you want to bind to.
        // For more details, see http://go.microsoft.com/fwlink/?LinkId=317598.
        [HttpPost]
        [ValidateAntiForgeryToken]
        public async Task<IActionResult> Edit(int id, [Bind("Id,Name,RollNo,Section,Program")] Student student)
        {
            if (id != student.Id)
            {
                return NotFound();
            }

            if (ModelState.IsValid)
            {
                try
                {
                    _context.Update(student);
                    await _context.SaveChangesAsync();
                }
                catch (DbUpdateConcurrencyException)
                {
                    if (!StudentExists(student.Id))
                    {
                        return NotFound();
                    }
                    else
                    {
                        throw;
                    }
                }
                return RedirectToAction(nameof(Index));
            }
            return View(student);
        }

        // GET: Students/Delete/5
        public async Task<IActionResult> Delete(int? id)
        {
            if (id == null)
            {
                return NotFound();
            }

            var student = await _context.Students
                .FirstOrDefaultAsync(m => m.Id == id);
            if (student == null)
            {
                return NotFound();
            }

            return View(student);
        }

        // POST: Students/Delete/5
        [HttpPost, ActionName("Delete")]
        [ValidateAntiForgeryToken]
        public async Task<IActionResult> DeleteConfirmed(int id)
        {
            var student = await _context.Students.FindAsync(id);
            if (student != null)
            {
                _context.Students.Remove(student);
            }

            await _context.SaveChangesAsync();
            return RedirectToAction(nameof(Index));
        }

        private bool StudentExists(int id)
        {
            return _context.Students.Any(e => e.Id == id);
        }
    }
}

Retrieve TempData in the Second Controller

In your second controller action, retrieve the TempData.

// GET: Teachers
public async Task<IActionResult> Index()
{
    // Recieve the Student Object data and then keep the data
    // Keep TempData for the next request
    var studentData = TempData["student"];
    TempData.Keep();
    return View(await _context.Teachers.ToListAsync());
}

Complete Teacher Controller Code

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.Mvc.Rendering;
using Microsoft.EntityFrameworkCore;
using DataTransferBetweenControllersinASPNETCoreMVC.DatbaseContext;
using DataTransferBetweenControllersinASPNETCoreMVC.Models;

namespace DataTransferBetweenControllersinASPNETCoreMVC.Controllers
{
    public class TeachersController : Controller
    {
        private readonly AppDbContext _context;

        public TeachersController(AppDbContext context)
        {
            _context = context;
        }

        // GET: Teachers
        public async Task<IActionResult> Index()
        {
            // Recieve the Student Object data and then keep the data
            var studentData = TempData["student"];
            TempData.Keep();
            return View(await _context.Teachers.ToListAsync());
        }

        // GET: Teachers/Details/5
        public async Task<IActionResult> Details(int? id)
        {
            if (id == null)
            {
                return NotFound();
            }

            var teacher = await _context.Teachers
                .FirstOrDefaultAsync(m => m.Id == id);
            if (teacher == null)
            {
                return NotFound();
            }

            return View(teacher);
        }

        // GET: Teachers/Create
        public IActionResult Create()
        {
            return View();
        }

        // POST: Teachers/Create
        // To protect from overposting attacks, enable the specific properties you want to bind to.
        // For more details, see http://go.microsoft.com/fwlink/?LinkId=317598.
        [HttpPost]
        [ValidateAntiForgeryToken]
        public async Task<IActionResult> Create([Bind("Id,Name,Course,Department")] Teacher teacher)
        {
            if (ModelState.IsValid)
            {
                _context.Add(teacher);
                await _context.SaveChangesAsync();
                return RedirectToAction(nameof(Index));
            }
            return View(teacher);
        }

        // GET: Teachers/Edit/5
        public async Task<IActionResult> Edit(int? id)
        {
            if (id == null)
            {
                return NotFound();
            }

            var teacher = await _context.Teachers.FindAsync(id);
            if (teacher == null)
            {
                return NotFound();
            }
            return View(teacher);
        }

        // POST: Teachers/Edit/5
        // To protect from overposting attacks, enable the specific properties you want to bind to.
        // For more details, see http://go.microsoft.com/fwlink/?LinkId=317598.
        [HttpPost]
        [ValidateAntiForgeryToken]
        public async Task<IActionResult> Edit(int id, [Bind("Id,Name,Course,Department")] Teacher teacher)
        {
            if (id != teacher.Id)
            {
                return NotFound();
            }

            if (ModelState.IsValid)
            {
                try
                {
                    _context.Update(teacher);
                    await _context.SaveChangesAsync();
                }
                catch (DbUpdateConcurrencyException)
                {
                    if (!TeacherExists(teacher.Id))
                    {
                        return NotFound();
                    }
                    else
                    {
                        throw;
                    }
                }
                return RedirectToAction(nameof(Index));
            }
            return View(teacher);
        }

        // GET: Teachers/Delete/5
        public async Task<IActionResult> Delete(int? id)
        {
            if (id == null)
            {
                return NotFound();
            }

            var teacher = await _context.Teachers
                .FirstOrDefaultAsync(m => m.Id == id);
            if (teacher == null)
            {
                return NotFound();
            }

            return View(teacher);
        }

        // POST: Teachers/Delete/5
        [HttpPost, ActionName("Delete")]
        [ValidateAntiForgeryToken]
        public async Task<IActionResult> DeleteConfirmed(int id)
        {
            var teacher = await _context.Teachers.FindAsync(id);
            if (teacher != null)
            {
                _context.Teachers.Remove(teacher);
            }

            await _context.SaveChangesAsync();
            return RedirectToAction(nameof(Index));
        }

        private bool TeacherExists(int id)
        {
            return _context.Teachers.Any(e => e.Id == id);
        }
    }
}

Keeping TempData for Subsequent Requests

By default, TempData is meant for a single subsequent request. If you want to persist TempData for more than one subsequent request, you can use the Keep method.

// GET: Teachers
public async Task<IActionResult> Index()
{
    // Recieve the Student Object data and then keep the data
    var studentData = TempData["student"];
    TempData.Keep();
    return View(await _context.Teachers.ToListAsync());
}

GitHub Project Link: https://github.com/SardarMudassarAliKhan/DataTransferBetweenControllersinASPNETCoreMVC

Conclusion

Passing temporary data between controllers in ASP.NET Core MVC can be achieved effectively using TempData. TempData allows you to store and retrieve data for the current request and the subsequent redirect. By setting TempData in one controller and retrieving it in another, you can facilitate the exchange of information between different parts of your application.

Remember to be mindful of TempData's one-time read nature; it is marked for deletion after being read, so use the Keep method if you need to persist the data for more than one subsequent request.

TempData provides a convenient mechanism for sharing short-lived data between controllers during a user's interaction with your ASP.NET Core MVC application.