How to Write JSON Into File in C#

1. The JSON Format
2. Download and Install Json.NET
3. Write JSON Into File Using Json.NET

In this post, we’ll learn how to use the C# programming language to construct basic JSON objects and write them into a file. To begin, you must have a solid understanding of what JSON is.

The JSON Format

JSON stands for JavaScript Object Notation and is a standard for exchanging minimal data. It uses a portion of the JavaScript programming language as its foundation.

JSON is a total language agnostic structure and uses no special characters. It is simple for people to read and write in JSON and for computers to produce and interpret JSON data.

An alternative to XML, it provides built-in support for the most fundamental data types. The term JavaScript Object Notation refers to the syntax used in both JavaScript and JSON.

Since it is a text-based language, it is simpler for the user to read, and at the same time, it is simpler for machines to interpret. Not years back, programmers used to rely on XML to facilitate communication across different service applications like web services.

However, users began investigating JSON as a possible alternative data serialization standard as the Web API gained popularity.

Download and Install Json.NET

To serialize data in the JSON format, we may either make use of the native class that is provided by the .NET Framework or use any other third-party component. We will use the NewtonSoft serialization library to serialize the JSON structure in this tutorial.

1. To get started, we must prepare the Microsoft Visual Studio workplace and install the Newtonsoft package.

2. Launch Microsoft Visual Studio and choose File from the menu bar, then New and the Project option.

3. Select Visual C# from the left side and then click on Console App (.NET Framework). Give an appropriate name and locate your project.

   We named it writejsonByZeeshan. After giving a name to it, click on OK.

   

4. Now that the project has been created, we will include a reference to Json.NET. To do this, we will right-click on the Solution Explorer area and choose Manage NuGet Packages for Solution.

5. After selecting Newtonsoft.Json, choose Install from the panel on the right.

   

6. After the download is finished, the component will be installed, and Json.NET will display a checkmark in the color green.

   

7. Now, you will discover that a reference for Newtonsoft.json has been added if you go to reference in the Solution Explorer. After Newtonsoft.json has been added, it’s time for us to construct the code that will create JSON.

Write JSON Into File Using Json.NET

The reference to Newtonsoft was previously included in our solution when it was first developed. Now is the time to begin working on the first code that will serialize and produce a JSON.

Let’s get started with a basic JSON structure, and then as we go along, let’s progressively advance towards more complicated structures while going line by line through the code and analyzing its functioning in more depth. Let’s begin by putting structure into a JSON file by first adding a new class to our project.

1. To begin, add the following libraries in the Main():

   using Newtonsoft.Json;
   using System;
   using System.Collections.Generic;
   using System.IO;
   using System.Linq;
   using System.Text;
   using System.Threading.Tasks;
   

2. To add a class, right-click on the Solution Explorer panel, left-click on Add, and choose a class from the drop-down menu. After giving it an acceptable name, like we named the Student class, the last step is to click the Add button.

   

3. Let’s start defining the variable objects in the new class after successfully creating them. We included the Name, Rollnum, Grade, and City in the Student class and assigned the following values.

   class Student {
     public string Name = "Muhammad Zeeshan";
     public int Rollnum = 3227;
     public string Grade = "A";
     public string City = "Islamabad";
   }
   

4. So, we’ll create an instance of the Student class named s in our Main function.

   Student s = new Student();
   

5. Then, with the JsonConvert.SerializeObject method, we will transform the class object we just specified into JSON format. Let’s put the serialized data into a string variable named SerializedJsonResult.

   string SerializedJsonResult = JsonConvert.SerializeObject(s);
   

6. Now that data has been serialized into a JSON format, we must provide a location for it to be saved. A string variable named jsonpath will be used for it.

   string jsonpath = "D:/jsondata/studentdata.json";
   

7. We’ll use the if condition to check path if it’s correct or not. If the path is already there, the code will overwrite the existing one by making a new one, destroying the old one.

   if (File.Exists(jsonpath)) {
     File.Delete(jsonpath);
     using (var st = new StreamWriter(jsonpath, true)) {
       st.WriteLine(SerializedJsonResult.ToString());
       st.Close();
     }
   }
   

8. If the path is unavailable, then else-if will create a new path and write the JSON to the file.

   else if (!File.Exists(jsonpath)) {
     using (var st = new StreamWriter(jsonpath, true)) {
       st.WriteLine(SerializedJsonResult.ToString());
       st.Close();
     }
   }
   

Complete Source Code

Example Code (Student Class):

class Student {
  public string Name = "Muhammad Zeeshan";
  public int Rollnum = 3227;
  public string Grade = "A";
  public string City = "Islamabad";
}

Example Code (Main Class):

using Newtonsoft.Json;
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace writejsonByZeeshan {
  class Program {
    static void Main(string[] args) {
      Student s = new Student();
      string SerializedJsonResult = JsonConvert.SerializeObject(s);

      string jsonpath = "D:/jsondata/studentdata.json";
      if (File.Exists(jsonpath)) {
        File.Delete(jsonpath);
        using (var st = new StreamWriter(jsonpath, true)) {
          st.WriteLine(SerializedJsonResult.ToString());
          st.Close();
        }
      }

      else if (!File.Exists(jsonpath)) {
        using (var st = new StreamWriter(jsonpath, true)) {
          st.WriteLine(SerializedJsonResult.ToString());
          st.Close();
        }
      }
    }
  }
}

Output:

{"Name":"Muhammad Zeeshan","Rollnum":3227,"Grade":"A","City":"Islamabad"}