# JSON Serializer

We need to install a NuGet package called: Newtonsoft.Json.

Let's create a variable phone with some properties:

var phone = new Phone
{
    Manufacturer = "Apple",
    Model = "iPhone X",
    Price = 1200.00
};

Then, press Ctrl and . on the Phone class to generate it.

internal class Phone
{
    public string Manufacturer { get; set; }
    public string Model { get; set; }
    public double Price { get; set; }
}

Now, we can try to serialize this object into a JSON string:

var phoneAsJsonString = JsonConvert.SerializeObject(phone);

Press same keys on JsonConvert to add the using statement.

Let's print it to the console and see what we get:

Console.WriteLine(phoneAsJsonString);

And the result is:

{"Manufacturer":"Apple","Model":"iPhone X","Price":1200.0}

Cool! This is the object serialized into JSON.

We have the option to indent the code to be displayed more nicely:

var phoneAsJsonString = JsonConvert.SerializeObject(phone, Formatting.Indented);
Console.WriteLine(phoneAsJsonString);

Now, this prints:

{
  "Manufacturer": "Apple",
  "Model": "iPhone X",
  "Price": 1200.0
}

Which is indeed more readable for us 👏

As you can see the format is lightweight and easy to interchange between different systems.

Also, if you are familiar with JavaScript, this is the same notation for JS objects.

Now, we can do the opposite: because we serialized our object into a JSON string, we can deserialize it into an object again.

var phoneDeserialized = JsonConvert.DeserializeObject<Phone>(phoneAsJsonString);
Console.WriteLine(phoneDeserialized);

Two simple things to consider here:

1. notice that we need to specify the type of the object (in our case <Phone>)
2. it prints the qualified name (the name of the class). We need to override the ToString method if we want to print its properties instead of its class name.

So, let's override the ToString method to print something more... meaningful, I guess 😀

public override string ToString()
{
    return $"{Manufacturer} {Model} ${Price}";
}

This prints:

Apple iPhone X $1200

Also, there is another serializer which is used internally by .NET called JavaScriptSerializer.

Even Microsoft recommends developers to use the Newtonsoft.Json NuGet package. It's way faster, easier to use etc.

You can find the source code on GitHub

# Data Persistency

We are going to see how to use this JSON serializer to persist data locally in a file.

It's very simple ☺️

First, let's write the JSON string to a file called Phone.json:

File.WriteAllText("Phone.json", phoneAsJsonString);

By default, this file is created in the bin/Debug folder. To find it, you need to right click on the project and open it in File Explorer. There, you can see the folder.

Now, let's read the file and use the string from the file to deserialize the Phone object:

var phoneStringFromFile = File.ReadAllText("Phone.json");

var phoneDeserialized = JsonConvert.DeserializeObject<Phone>(phoneStringFromFile);
Console.WriteLine(phoneDeserialized);

You can find the source code on GitHub