I was working on one of my projects last week and stuck in a problem. I was trying to pass a class object and List of a class object to the Asp.Net Web API controller from my Jquery Ajax method (maybe you also encounter it while working with Angular and ASP.NET MVC or any other technology). After some research, I got to know that the Web API controller can’t accept multiple complex objects, so we must send it as a single object. Let me illustrate with my example and its resolution.

Jquery Code : -

  var SaleModel = new Object();  
       SaleModel.id = “1”;  // for example
       SaleModel.customer_id = $("#ddlCustomer").val(); 
   
  var SaleDetailModel = new Object();
    SaleDetailModel.id = “1”;
    SaleDetailModel.quantity = “10”;
  var lstSaleDetail = [];   // javascript array
    lstSaleDetail.push(SaleDetailModel);

 $.ajax({
      type: 'POST',
      data: 
      "{'obj': '"+JSON.stringify(SaleModel) + "',
      'lstSaleDetail':  '"+JSON.stringify(lstSaleDetail)+ "' }",
      headers: {
                 'Authorization': 'Bearer ' + authData.token
             },
      url: 'http://localhost:53807/api/sale/addsale',
      dataType: 'json',
      contentType: 'application/json',
      success: function (data) {
                if (data == true) {
                    alert("Sale Added Successfully!!!");
                }
            },
      error: function (xhr) {
                alert(xhr.responseText);
          }
  });

C# Code : -

       public class SaleModel
       {
          public int id {get;set;}
          public int customer_id {get;set;}
       }

       public class SaleDetailModel
       {
         public int id {get;set;}
         public int quantity {get;set;}
       }

       [HttpPost]
       public bool AddSale(SaleModel obj, List<SaleDetailModel> lstSaleDetail)
       {            
          SaleBusService objSale = new SaleBusService();
          return objSale.saveSale(obj, lstSaleDetail);           
       }

Solution : -

To fix the problem, we need to pass it as a single object that requires a modification in the above code. Below is the C# code. I have added the List Object of the SaleDetailModel class to the SaleModel Class as per my needs. You can create a new request class that contains both SaleModel and SaleDetailModel Objects.

C# Code :

public class SaleModel
{
   public int id {get;set;}
   public int customer_id {get;set;}
   // I have added the list here
   public List<SaleDetailModel> lstSaleDetail {get;set;} 
}

public class SaleDetailModel
{
   public int id {get;set;}
   public int quantity {get;set;}
}


[HttpPost]
public bool AddSale(SaleModel obj)
 {            
      SaleBusService objSale = new SaleBusService();
      return objSale.saveSale(obj, obj.lstSaleDetail);           
 }

Jquery Code :

var SaleModel = new Object();  
       SaleModel.id = “1”;  // for example
SaleModel.customer_id = $("#ddlCustomer").val(); 
   
var SaleDetailModel = new Object();
    SaleDetailModel.id = “1”;
    SaleDetailModel.quantity = “10”;
var lstSaleDetail = [];   // javascript array
lstSaleDetail.push(SaleDetailModel);

 $.ajax({
            type: 'POST',
     data: JSON.stringify(SaleModel) ,
            headers: {
                 'Authorization': 'Bearer ' + authData.token
             },
            url: 'http://localhost:53807/api/sale/addsale',
            dataType: 'json',
            contentType: 'application/json',
            success: function (data) {
                if (data == true) {
                    alert("Sale Added Successfully!!!");
                }
            },
            error: function (xhr) {
                alert(xhr.responseText);
            }
        });

C# has prosperous data types for storing any data/information. We have three sorts Object, Var, and Dynamic for storing any data in C#. So how about we observe how these three separate with each other with cases.

Object:

It was first introduced in C# version 1.0. An Object is a base class of .Net as we all know, its purpose is the same, it can store all kinds of data. It is a compile-time variable. We can also pass objects as method arguments because methods can return Object type. At compile time compiler doesn't have much information for the use type, so it is very productive when we don't know the type of data. But when we have to use data inside an object we need to cast it to the required data type. The object is the most abstraction for all types in C# and its reference type. An object can box any type of data. When using an object to store data that is called boxing and for using that data need to unbox it.

        Object emp_id = 10; // int 
        Object order_porduct = new Order(); //order object
        Object customer_name = "John"; //string
        //unbox
        string customer = customer_name.ToString();
        //perform string operation now
        customer.Trim();

Var:

It comes in C # 3.0 versions. Var is a compile-time variable. It is also used to store any type of data, but the additional work is that declaration time we have to initialize the var type is mandatory. So that's why var type can only work within the specified scope not out of this because its method does not return object type and also cannot be passed as a method argument, but it's a type-safe and compiler know all data, which is stored in var type. That's why while using we are not required to cast var type we can directly use it.

        var qty = 10; // int
        var brder_ID = 10d; // double
        var brand = "samsung"; // string 

Dynamic:

In C# 4.0 we got dynamic a run-time variable that can store all kinds of data. The dynamic keyword has some same characteristics as Object that it doesn't have any information about data and not type-safe, but an advantage we have that it can be passed as a method argument in return it gives dynamic type. It does not require cast when using its data, but we should have knowledge that which properties and methods are linked with stored data type because if we use any other property or method, then it will throw an error. We can use it when doing code with reflection, dynamics, or playing COM objects because in a very short time we can code big tasks with fewer lines.

         dynamic employee = new Class();
         employee.Age = 30;
         employee.Name = "John Doe";
         employee.Course = new Course();

         employee.Name; // read a string
         employee.Age; // read an int
         employee.Course.Name; // read a property

This article is about the Difference Between ToString and Convert.ToString Method in C#.

ToString and Convert.ToString Method in C#

Both methods have the ability to convert a value to a string. The main difference between the two methods is that ToString() method can’t handle Null values, so if you use this method, you will experience a Null Reference Exception in your code at some point in time (as shown below Example). On the other hand Convert.ToString() method can handle Null values. So, as a good coding practice and to be on the safe side, experts recommend always use Convert.ToString() method.

We have used below mentioned examples to demonstrate the difference between ToString and Convert.ToString methods.

.ToString() Example:

In C#, if you declare a string variable and do not assign any value to the variable, the variable takes a null value by default. In this case, if you use the ToString() method, the program will raise a null reference exception.

 using System;

namespace DemoToString
{
    public class Program
    {
        static void Main(string[] args)
        {
            Object objStr = null;
            //Below line will throw NullReference Exception
            //Because .ToString() can't handle Null values
            string val = objStr.ToString(); 
            Console.WriteLine(val);
            Console.ReadLine();
        }
    }
}

When we run the program it will give us null reference exception because the ToString() method in C# expects that the object cannot be NULL when called on it. In our example, the object objStr is Null, and we call ToString() on the NULL object, so it gives a NULL Reference exception.

Convert.ToString() Example:

Let's see what happens when we utilize the Convert.Tostring() method in the above example. Now, after making the changes, run the program, and it should execute correctly. So to put it plainly, the Convert.ToString() method handles null, and the ToString() method does not deal with Null and tosses an exception.

using System;

namespace DemoConvertToString
{
    public class Program
    {
        static void Main(string[] args)
        {
            Object objStr = null;
            //Below line will Return Null Or Blank
            string val = Convert.ToString(objStr);
            Console.WriteLine(val);
            Console.ReadLine();
        }
    }
}

Convert is a static class in the .Net System namespace, and if you noticed that when you write.ToString() It is in a dark blue color(which means that this method is only available in C#) and Convert.ToString() is in light blue color which means it is global and available in other .Net languages as well.

I will go through the difference between object, var, and dynamic keywords through some examples in my next article. Today, I have tried to explain the difference between .tostring and convert.tostring methods. I trust this article will assist you with your requirements. I hope to receive your feedback. Please post your criticism, questions, or remarks on this article.