Dotnet Core, Ajax and Databases

I have project I am working on. Not to worry about how it looks right now the code is on github https://github.com/althepal78/melskitchen

So I am trying to add ajax to the chat section of it so that it can not keep reloading the whole page. I am not sure where to add the AJax call or use it with Dotnet core and the MySQL database because it is confusing. Now I have gotten it to work just not the ajax stuff. I have added the nuget package and the min script to the layout. I am also using vs code not vs 2019. this is what I am using Dotnet core, EF 3.1, and MySQL workbench. Can someone help me understand where to properly do this in my code. If I have to I will add my code here as well.

I got it to work Amen

here is the answer on stack overflow

https://stackoverflow.com/questions/65815325/how-to-use-ajax-with-mvc-mysql-and-entity-framework-no-razor-pages/65816660?noredirect=1#comment116604642_65816660

so if you want to know what I am trying to do here is my question in greater detailed in stackoverflow because someone tried to help me there and it didn't work it gives me an alert. I don't want a freaking a lert I am sorry I have ptsd and this is driving me crazy

https://stackoverflow.com/questions/65815325/how-to-use-ajax-with-mvc-mysql-and-entity-framework-no-razor-pages?

So the information on stackoverflow is doing this to me at this time I made a video about it

https://youtu.be/KEub5IdYkkQ

@Sachin Singh

I tried that and it still did not work, like I said I wish I could zoom with you for about 20 mins just to get a real understanding of what you are doing. It was working before the Ajax call so I am confused why I needed to add the foreign key.

@Kiran Mohanty

what do you mean by requirement diagram? I am just doing things off my mind with what and how I learned how to do this. I wish I coould zooom with you or Singh for about 20 minutes all my code is at my github except the few things I changed and they were in this section.

namespace ToledosSite.Models
{
public class Message
{
[Key]
public int MessageID { get; set; }
public string TheMessage { get; set; }
// one to many
[ForeignKey("User")] // the foreign Key
public int UserID { get; set; }
public User Messenger { get; set; }
public DateTime CreateAt { get; set; } = DateTime.Now;
public DateTime UpdatedAt { get; set; } = DateTime.Now;
}
}

then

class="m-4">// this was originally not a partial
"PartialMessage">

then my controller I basically only changed

[HttpPost("NewMessage/Add")]
/ this was originally public IActionResult
public JsonResult NewMessage( Message newMessage)
{
User userInDB = GetUserInDB();
Message thisMessage = newMessage;
thisMessage.UserID = userInDB.UserID;
DBContext.Messages.Add(thisMessage);
DBContext.SaveChanges();
return Json(thisMessage);
}

my orginal code is on my github https://github.com/althepal78/melskitchen

Hi,

Here is what i found.

class User {
public int UserID { get; set; }
public List<Recipe> MyRecipes {get;set;}
public List<Like> MyLikes {get;set;}
public List<Message> MyMessages {get;set;}
}
class Recipe {
public int UserID { get; set; }
public User Creator { get; set; }
public List<Like> Liked {get;set;}
}
class Message {
public int UserID { get; set; }
public User Messenger { get; set; }
}
class Like {
public int UserID { get; set; }
public int RecipeID { get; set; }
public User Liker { get; set; }
public Recipe Rec { get; set; }
}

This object structure creates circular reference and application fails to create JSON object . Can you please post your requirement diagram ? As per me, object structure you may need to change.

one to many relationship is not configured correctly.

namespace ToledosSite.Models
{
public class Message
{
[Key]
public int MessageID { get; set; }
public string TheMessage { get; set; }
[ForeignKey("User")]
public int UserID { get; set; }
public User Messenger { get; set; }
public DateTime CreateAt { get; set; }
public DateTime UpdatedAt { get; set; }
}
}

So my code is listed below can anyone help me I am getting this error

An unhandled exception occurred while processing the request.

JsonException: A possible object cycle was detected which is not supported. This can either be due to a cycle or if the object depth is larger than the maximum allowed depth of 32.

System.Text.Json.ThrowHelper.ThrowInvalidOperationException_SerializerCycleDetected(int maxDepth)

using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Mvc;
using Microsoft.Extensions.Logging;
using ToledosSite.Models;
using ToledosSite.Context;
using Microsoft.AspNetCore.Identity;
using Microsoft.AspNetCore.Http;
using Microsoft.EntityFrameworkCore;
namespace ToledosSite.Controllers
{
public class HomeController : Controller
{
private HomeContext DBContext;
public HomeController(HomeContext context)
{
DBContext = context;
}
public User GetUserInDB()
{
return DBContext.Users.FirstOrDefault(u => u.UserID == HttpContext.Session.GetInt32("UserId"));
}
[HttpPost("adduser")]
public IActionResult AddUser(User user)
{
if (ModelState.IsValid)
{
// If a User exists with provided email
if (DBContext.Users.Any(u => u.Email == user.Email))
{
// Manually add a ModelState error to the Email field, with provided
// error message
ModelState.AddModelError("Email", "Email already in use!");
// You may consider returning to the View at this point
return View("LoginOrRegister");
}
else
{
PasswordHasher Hasher = new PasswordHasher();
user.Password = Hasher.HashPassword(user, user.Password);
DBContext.Users.Add(user);
DBContext.SaveChanges();
HttpContext.Session.SetInt32("UserId", user.UserID);
return RedirectToAction("Index");
}
}
return View("LoginOrRegister");
}
[HttpGet("")]
public IActionResult Index()
{
ViewBag.User = GetUserInDB();
ViewBag.AllRecipes = DBContext.Recipes
.Include(l => l.Liked)
.Include(cr => cr.Creator)
.ToList();
return View();
}
[HttpPost("login")]
public IActionResult Login(LoginUser log)
{
if (ModelState.IsValid)
{
// If inital ModelState is valid, query for a user with provided email
var userInDb = DBContext.Users.FirstOrDefault(u => u.Email == log.LoginEmail);
// If no user exists with provided email
if (userInDb == null)
{
// Add an error to ModelState and return to View!
ModelState.AddModelError("LoginEmail", "Invalid Email/Password");
return View("LoginOrRegister");
}
// Initialize hasher object
var hasher = new PasswordHasher();
// verify provided password against hash stored in db
var result = hasher.VerifyHashedPassword(log, userInDb.Password, log.LoginPassword);
// result can be compared to 0 for failure
if (result == 0)
{
// handle failure (this should be similar to how "existing email" is handled)
ModelState.AddModelError("LoginPassword", "Invalid Email/Password");
return View("LoginOrRegister");
}
HttpContext.Session.SetInt32("UserId", userInDb.UserID);
ViewBag.userID = HttpContext.Session.GetInt32("UserId");
return RedirectToAction("Index", ViewBag.userID);
}
return View("LoginOrRegister");
}
[HttpGet("logout")]
public IActionResult Logout()
{
HttpContext.Session.Clear();
return RedirectToAction("Index");
}
[HttpGet("LoginOrRegister")]
public IActionResult LogOrReg()
{
return View("LoginOrRegister");
}
[HttpGet("addrecipe")]
public IActionResult AddRecipe(int userID)
{
return View("AddRecipe");
}
[HttpPost("createrecipe")]
public IActionResult CreateRecipe(Recipe recipe)
{
User userInDb = GetUserInDB();
if (userInDb != null)
{
if (ModelState.IsValid)
{
recipe.UserID = userInDb.UserID;
recipe.Creator = userInDb;
DBContext.Recipes.Add(recipe);
DBContext.SaveChanges();
return RedirectToAction("Index");
}
}
return View("AddRecipe");
}
[HttpGet("ShowRecipe/{recipeID}")]
public IActionResult ShowRecipe(int recipeID)
{
ViewBag.User = GetUserInDB();
Recipe thisRecipe = DBContext.Recipes
.Include(c => c.Creator)
.FirstOrDefault(r => r.RecipeID == recipeID);
return View(thisRecipe);
}
[HttpGet("DelteRecipe/{recipeID}")]
public IActionResult DelteRecipe(int recipeID)
{
Recipe thisOne = DBContext.Recipes
.FirstOrDefault(l => l.RecipeID == recipeID);
DBContext.Recipes.Remove(thisOne);
DBContext.SaveChanges();
return RedirectToAction("");
}
[HttpGet("Liked/{recipeID}/{userID}")]
public IActionResult Liked(int recipeID, int userID)
{
Like liked = new Like();
liked.RecipeID = recipeID;
liked.UserID = userID;
DBContext.Likes.Add(liked);
DBContext.SaveChanges();
return RedirectToAction("Index");
}
[HttpGet("Edit/{recipeID}")]
public IActionResult Edit(int recipeID)
{
Recipe thisOne = DBContext.Recipes.FirstOrDefault(r => r.RecipeID == recipeID);
return View("Edit", thisOne);
}
[HttpPost("EditRecipe/{recipeID}")]
public IActionResult EditRecipe(Recipe recipe)
{
Recipe rec = DBContext.Recipes.FirstOrDefault(f => f.RecipeID == recipe.RecipeID);
User UserInDb = GetUserInDB();
if (UserInDb != null)
{
if (ModelState.IsValid)
{
rec.RecipeName = recipe.RecipeName;
rec.Ingredients = recipe.Ingredients;
rec.Directions = recipe.Directions;
rec.UpdatedAt = DateTime.Now;
DBContext.SaveChanges();
return RedirectToAction("Index");
}
}
return View("Edit", recipe);
}
[HttpGet("wall")]
public IActionResult Wall(int userID)
{
ViewBag.User = GetUserInDB();
// if(ViewBag.User == null)
// {
// return RedirectToAction("Index");
// }
ViewBag.Messages = DBContext.Messages
.Include(i => i.Messenger)
.ToList();
return View();
}
[HttpPost("NewMessage/Add")]
public JsonResult NewMessage( Message newMessage)
{
User userInDB = GetUserInDB();
Message thisMessage = newMessage;
thisMessage.UserID = userInDB.UserID;
DBContext.Messages.Add(thisMessage);
DBContext.SaveChanges();
return Json(thisMessage);
}
[ResponseCache(Duration = 0, Location = ResponseCacheLocation.None, NoStore = true)]
public IActionResult Error()
{
return View(new ErrorViewModel { RequestId = Activity.Current?.Id ?? HttpContext.TraceIdentifier });
}
}
}
//// my wall
@model Message
class="jumbotron p-2 m-3">
"/">class="logo" src="/images/melysLogo.jpg" alt="Logo Image">
@if (ViewBag.User == null)
{
class="mr-2" href="/LoginOrRegister">Login Or Register
}
else
{
"/logout">Logout |
"/AddRecipe"> Add Recipe|
class="mr-2" href="/">Dashboard
}
"font-size:x-large;">Melly's Underground Cuisine

I wish I could message you man so I can ask you a few questions of where I would do some stuff because I tried some stuff just getting lost

even if you don't add the jsonOption then also the ajax will work , so simply issue an ajax get or post request from view to controller as i described in the example at it should work.

I dont have options.serializer.contractresolver in my setup so this does not work for me I get unresolve information

@Sachin Singh, does it matter what MVC I am doing? Like is this always the way even when you trying to get the information from a database?

these are the steps

public void ConfigureServices(IServiceCollection services)
{
services.AddMvc()
.AddJsonOptions(options => options.SerializerSettings.ContractResolver = new DefaultContractResolver());
}

public class HomeController : Controller
{
// GET: Home
public IActionResult Index()
{
return View();
}
[HttpPost]
public JsonResult AjaxMethod(string name)
{
PersonModel person = new PersonModel
{
Name = name,
DateTime = DateTime.Now.ToString()
};
return Json(person);
}
}

"text" id="txtName"/>
"button" id="btnGet" value="Get Current Time"/>
"text/javascript" src="https://ajax.googleapis.com/ajax/libs/jquery/1.8.3/jquery.min.js">
"text/javascript">
$(function () {
$("#btnGet").click(function () {
$.ajax({
type: "POST",
url: "/Home/AjaxMethod",
data: { "name": $("#txtName").val() },
success: function (response) {
alert("Hello: " + response.Name + " .\nCurrent Date and Time: " + response.DateTime);
},
failure: function (response) {
alert(response.responseText);
},
error: function (response) {
alert(response.responseText);
}
});
});
});

11 Replies

Know the answer? Post it — somebody with the same question will find it here.

ALTHEPAL78 ALTHEPAL785y ago
I got it to work Amen

here is the answer on stack overflow

https://stackoverflow.com/questions/65815325/how-to-use-ajax-with-mvc-mysql-and-entity-framework-no-razor-pages/65816660?noredirect=1#comment116604642_65816660
ALTHEPAL78 ALTHEPAL785y ago
so if you want to know what I am trying to do here is my question in greater detailed in stackoverflow because someone tried to help me there and it didn't work it gives me an alert. I don't want a freaking a lert I am sorry I have ptsd and this is driving me crazy

https://stackoverflow.com/questions/65815325/how-to-use-ajax-with-mvc-mysql-and-entity-framework-no-razor-pages?

So the information on stackoverflow is doing this to me at this time I made a video about it
https://youtu.be/KEub5IdYkkQ
ALTHEPAL78 ALTHEPAL785y ago
@Sachin Singh
I tried that and it still did not work, like I said I wish I could zoom with you for about 20 mins just to get a real understanding of what you are doing. It was working before the Ajax call so I am confused why I needed to add the foreign key.

@Kiran Mohanty
what do you mean by requirement diagram? I am just doing things off my mind with what and how I learned how to do this. I wish I coould zooom with you or Singh for about 20 minutes all my code is at my github except the few things I changed and they were in this section.
namespace ToledosSite.Models
{
    public class Message
    {
        [Key]
        public int MessageID { get; set; }

        public string TheMessage { get; set; }

        // one to many
        [ForeignKey("User")]  // the foreign Key
        public int UserID { get; set; }

        public User Messenger { get; set; }


        public DateTime CreateAt { get; set; } = DateTime.Now;

        public DateTime UpdatedAt { get; set; } = DateTime.Now;
    }
}
then

class="m-4">// this was originally not a partial
   "PartialMessage">
then my controller I basically only changed
[HttpPost("NewMessage/Add")]
/ this was originally public IActionResult
       public JsonResult NewMessage( Message newMessage)
       {

           User userInDB = GetUserInDB();
           Message thisMessage = newMessage;
           thisMessage.UserID = userInDB.UserID;

           DBContext.Messages.Add(thisMessage);
           DBContext.SaveChanges();

           return Json(thisMessage);
       }
my orginal code is on my github https://github.com/althepal78/melskitchen
Kiran Mohanty5y ago
Hi,
Here is what i found.
class User {
    public int UserID { get; set; }
    public List<Recipe> MyRecipes {get;set;}
    public List<Like> MyLikes {get;set;}
    public List<Message> MyMessages {get;set;}
}

class Recipe {
   public int UserID { get; set; }
   public User Creator { get; set; }
   public List<Like> Liked {get;set;}
}

class Message {
   public int UserID { get; set; }
   public User Messenger { get; set; }
}

class Like {
   public int UserID { get; set; }
   public int RecipeID { get; set; }
   public User Liker { get; set; }
   public Recipe Rec { get; set; }
}
This object structure creates circular reference and application fails to create JSON object . Can you please post your requirement diagram ? As per me, object structure you may need to change.
Sachin Singh5y ago
one to many relationship is not configured correctly.
namespace ToledosSite.Models
{
    public class Message
    {
        [Key]
        public int MessageID { get; set; }

        public string TheMessage { get; set; }

       [ForeignKey("User")]
        public int UserID { get; set; }

        public User Messenger { get; set; }


        public DateTime CreateAt { get; set; }

        public DateTime UpdatedAt { get; set; }
    }
}
ALTHEPAL78 ALTHEPAL785y ago
So my code is listed below can anyone help me I am getting this error

An unhandled exception occurred while processing the request.

JsonException: A possible object cycle was detected which is not supported. This can either be due to a cycle or if the object depth is larger than the maximum allowed depth of 32.

System.Text.Json.ThrowHelper.ThrowInvalidOperationException_SerializerCycleDetected(int maxDepth)
using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Mvc;
using Microsoft.Extensions.Logging;
using ToledosSite.Models;
using ToledosSite.Context;
using Microsoft.AspNetCore.Identity;
using Microsoft.AspNetCore.Http;
using Microsoft.EntityFrameworkCore;


namespace ToledosSite.Controllers
{
    public class HomeController : Controller
    {
        private HomeContext DBContext;

        public HomeController(HomeContext context)
        {
            DBContext = context;
        }

        public User GetUserInDB()
        {
            return DBContext.Users.FirstOrDefault(u => u.UserID == HttpContext.Session.GetInt32("UserId"));
        }

        [HttpPost("adduser")]
        public IActionResult AddUser(User user)
        {

            if (ModelState.IsValid)
            {
                // If a User exists with provided email
                if (DBContext.Users.Any(u => u.Email == user.Email))
                {
                    // Manually add a ModelState error to the Email field, with provided
                    // error message
                    ModelState.AddModelError("Email", "Email already in use!");

                    // You may consider returning to the View at this point
                    return View("LoginOrRegister");
                }
                else
                {
                    PasswordHasher Hasher = new PasswordHasher();
                    user.Password = Hasher.HashPassword(user, user.Password);
                    DBContext.Users.Add(user);
                    DBContext.SaveChanges();
                    HttpContext.Session.SetInt32("UserId", user.UserID);
                    return RedirectToAction("Index");
                }
            }
            return View("LoginOrRegister");
        }

        [HttpGet("")]
        public IActionResult Index()
        {

            ViewBag.User = GetUserInDB();

            ViewBag.AllRecipes = DBContext.Recipes
                        .Include(l => l.Liked)
                        .Include(cr => cr.Creator)
                        .ToList();

            return View();
        }

        [HttpPost("login")]
        public IActionResult Login(LoginUser log)
        {
            if (ModelState.IsValid)
            {
                // If inital ModelState is valid, query for a user with provided email
                var userInDb = DBContext.Users.FirstOrDefault(u => u.Email == log.LoginEmail);
                // If no user exists with provided email
                if (userInDb == null)
                {
                    // Add an error to ModelState and return to View!
                    ModelState.AddModelError("LoginEmail", "Invalid Email/Password");
                    return View("LoginOrRegister");
                }

                // Initialize hasher object
                var hasher = new PasswordHasher();

                // verify provided password against hash stored in db
                var result = hasher.VerifyHashedPassword(log, userInDb.Password, log.LoginPassword);

                // result can be compared to 0 for failure
                if (result == 0)
                {
                    // handle failure (this should be similar to how "existing email" is handled)
                    ModelState.AddModelError("LoginPassword", "Invalid Email/Password");

                    return View("LoginOrRegister");
                }
                HttpContext.Session.SetInt32("UserId", userInDb.UserID);
                ViewBag.userID = HttpContext.Session.GetInt32("UserId");

                return RedirectToAction("Index", ViewBag.userID);
            }
            return View("LoginOrRegister");
        }

        [HttpGet("logout")]
        public IActionResult Logout()
        {

            HttpContext.Session.Clear();

            return RedirectToAction("Index");
        }

        [HttpGet("LoginOrRegister")]
        public IActionResult LogOrReg()
        {

            return View("LoginOrRegister");
        }

        [HttpGet("addrecipe")]
        public IActionResult AddRecipe(int userID)
        {
            return View("AddRecipe");
        }

        [HttpPost("createrecipe")]

        public IActionResult CreateRecipe(Recipe recipe)
        {
            User userInDb = GetUserInDB();
            if (userInDb != null)
            {
                if (ModelState.IsValid)
                {

                    recipe.UserID = userInDb.UserID;
                    recipe.Creator = userInDb;
                    DBContext.Recipes.Add(recipe);
                    DBContext.SaveChanges();
                    return RedirectToAction("Index");
                }
            }
            return View("AddRecipe");

        }

        [HttpGet("ShowRecipe/{recipeID}")]

        public IActionResult ShowRecipe(int recipeID)
        {


            ViewBag.User = GetUserInDB();
            Recipe thisRecipe = DBContext.Recipes

                         .Include(c => c.Creator)
                         .FirstOrDefault(r => r.RecipeID == recipeID);
            return View(thisRecipe);
        }

        [HttpGet("DelteRecipe/{recipeID}")]
        public IActionResult DelteRecipe(int recipeID)
        {
            Recipe thisOne = DBContext.Recipes
                            .FirstOrDefault(l => l.RecipeID == recipeID);

            DBContext.Recipes.Remove(thisOne);
            DBContext.SaveChanges();

            return RedirectToAction("");
        }

        [HttpGet("Liked/{recipeID}/{userID}")]
        public IActionResult Liked(int recipeID, int userID)
        {

            Like liked = new Like();

            liked.RecipeID = recipeID;
            liked.UserID = userID;
            DBContext.Likes.Add(liked);
            DBContext.SaveChanges();

            return RedirectToAction("Index");
        }
        [HttpGet("Edit/{recipeID}")]
        public IActionResult Edit(int recipeID)
        {
            Recipe thisOne = DBContext.Recipes.FirstOrDefault(r => r.RecipeID == recipeID);

            return View("Edit", thisOne);
        }

        [HttpPost("EditRecipe/{recipeID}")]
        public IActionResult EditRecipe(Recipe recipe)
        {
            Recipe rec = DBContext.Recipes.FirstOrDefault(f => f.RecipeID == recipe.RecipeID);

            User UserInDb = GetUserInDB();

            if (UserInDb != null)
            {
                if (ModelState.IsValid)
                {
                    rec.RecipeName = recipe.RecipeName;
                    rec.Ingredients = recipe.Ingredients;
                    rec.Directions = recipe.Directions;
                    rec.UpdatedAt = DateTime.Now;
                    DBContext.SaveChanges();
                    return RedirectToAction("Index");
                }
            }
            return View("Edit", recipe);
        }

        [HttpGet("wall")]
        public IActionResult Wall(int userID)
        {
            ViewBag.User = GetUserInDB();
            // if(ViewBag.User == null)
            // {
            //     return RedirectToAction("Index");
            // }
            ViewBag.Messages = DBContext.Messages
                                .Include(i => i.Messenger)
                                .ToList();

            return View();
        }

        [HttpPost("NewMessage/Add")]
        public JsonResult NewMessage( Message newMessage)
        {

            User userInDB = GetUserInDB();
            Message thisMessage = newMessage;
            thisMessage.UserID = userInDB.UserID;

            DBContext.Messages.Add(thisMessage);
            DBContext.SaveChanges();

            return Json(thisMessage);
        }





        [ResponseCache(Duration = 0, Location = ResponseCacheLocation.None, NoStore = true)]
        public IActionResult Error()
        {
            return View(new ErrorViewModel { RequestId = Activity.Current?.Id ?? HttpContext.TraceIdentifier });
        }
    }
}
//// my wall

@model Message

class="jumbotron p-2 m-3">
    "/">class="logo" src="/images/melysLogo.jpg" alt="Logo Image">


    @if (ViewBag.User == null)
    {
        class="mr-2" href="/LoginOrRegister">Login Or Register
    }
    else
    {
        "/logout">Logout |
        "/AddRecipe"> Add Recipe|
        class="mr-2" href="/">Dashboard
    }
    "font-size:x-large;">Melly's Underground Cuisine
class="messageboard m-3 p-3 rounded">
class="m-3 p-3 sizeclass">
@foreach (Message message in ViewBag.Messages)
{
class="d-flex justify-content-around m-3 p-3 ">
class="p-2 rounded largeLabel border">@message.TheMessage