How do I turn a C# object into a JSON string in .NET?
How do I turn a C# object into a JSON string in .NET?
Question
I have classes like these:
class MyDate
{
int year, month, day;
}
class Lad
{
string firstName;
string lastName;
MyDate dateOfBirth;
}
And I would like to turn a Lad object into a JSON string like this:
{
"firstName":"Markoff",
"lastName":"Chaney",
"dateOfBirth":
{
"year":"1901",
"month":"4",
"day":"30"
}
}
(without the formatting). I found this link, but it uses a namespace that's not in .NET 4. I also heard about JSON.NET, but their site seems to be down at the moment, and I'm not keen on using external DLL files.
Are there other options besides manually creating a JSON string writer?
Accepted Answer
You could use the JavaScriptSerializer class (add reference to System.Web.Extensions):
using System.Web.Script.Serialization;
var json = new JavaScriptSerializer().Serialize(obj);
A full example:
using System;
using System.Web.Script.Serialization;
public class MyDate
{
public int year;
public int month;
public int day;
}
public class Lad
{
public string firstName;
public string lastName;
public MyDate dateOfBirth;
}
class Program
{
static void Main()
{
var obj = new Lad
{
firstName = "Markoff",
lastName = "Chaney",
dateOfBirth = new MyDate
{
year = 1901,
month = 4,
day = 30
}
};
var json = new JavaScriptSerializer().Serialize(obj);
Console.WriteLine(json);
}
}
Popular Answer
Since we all love one-liners
... this one depends on the Newtonsoft NuGet package, which is popular and better than the default serializer.
Newtonsoft.Json.JsonConvert.SerializeObject(new {foo = "bar"})
Documentation: Serializing and Deserializing JSON
Read more… Read less…
Use Json.Net library, you can download it from Nuget Packet Manager.
Serializing to Json String:
var obj = new Lad
{
firstName = "Markoff",
lastName = "Chaney",
dateOfBirth = new MyDate
{
year = 1901,
month = 4,
day = 30
}
};
var jsonString = Newtonsoft.Json.JsonConvert.SerializeObject(obj);
Deserializing to Object:
var obj = Newtonsoft.Json.JsonConvert.DeserializeObject<Lad>(jsonString );
You can achieve this by using Newtonsoft.json. Install Newtonsoft.json from NuGet. And then:
using Newtonsoft.Json;
var jsonString = JsonConvert.SerializeObject(obj);
Wooou! Really better using a JSON framework :)
Here is my example using Json.NET (http://james.newtonking.com/json):
using System;
using System.Collections.Generic;
using System.Text;
using Newtonsoft.Json;
using System.IO;
namespace com.blogspot.jeanjmichel.jsontest.model
{
public class Contact
{
private Int64 id;
private String name;
List<Address> addresses;
public Int64 Id
{
set { this.id = value; }
get { return this.id; }
}
public String Name
{
set { this.name = value; }
get { return this.name; }
}
public List<Address> Addresses
{
set { this.addresses = value; }
get { return this.addresses; }
}
public String ToJSONRepresentation()
{
StringBuilder sb = new StringBuilder();
JsonWriter jw = new JsonTextWriter(new StringWriter(sb));
jw.Formatting = Formatting.Indented;
jw.WriteStartObject();
jw.WritePropertyName("id");
jw.WriteValue(this.Id);
jw.WritePropertyName("name");
jw.WriteValue(this.Name);
jw.WritePropertyName("addresses");
jw.WriteStartArray();
int i;
i = 0;
for (i = 0; i < addresses.Count; i++)
{
jw.WriteStartObject();
jw.WritePropertyName("id");
jw.WriteValue(addresses[i].Id);
jw.WritePropertyName("streetAddress");
jw.WriteValue(addresses[i].StreetAddress);
jw.WritePropertyName("complement");
jw.WriteValue(addresses[i].Complement);
jw.WritePropertyName("city");
jw.WriteValue(addresses[i].City);
jw.WritePropertyName("province");
jw.WriteValue(addresses[i].Province);
jw.WritePropertyName("country");
jw.WriteValue(addresses[i].Country);
jw.WritePropertyName("postalCode");
jw.WriteValue(addresses[i].PostalCode);
jw.WriteEndObject();
}
jw.WriteEndArray();
jw.WriteEndObject();
return sb.ToString();
}
public Contact()
{
}
public Contact(Int64 id, String personName, List<Address> addresses)
{
this.id = id;
this.name = personName;
this.addresses = addresses;
}
public Contact(String JSONRepresentation)
{
//To do
}
}
}
The test:
using System;
using System.Collections.Generic;
using com.blogspot.jeanjmichel.jsontest.model;
namespace com.blogspot.jeanjmichel.jsontest.main
{
public class Program
{
static void Main(string[] args)
{
List<Address> addresses = new List<Address>();
addresses.Add(new Address(1, "Rua Dr. Fernandes Coelho, 85", "15º andar", "São Paulo", "São Paulo", "Brazil", "05423040"));
addresses.Add(new Address(2, "Avenida Senador Teotônio Vilela, 241", null, "São Paulo", "São Paulo", "Brazil", null));
Contact contact = new Contact(1, "Ayrton Senna", addresses);
Console.WriteLine(contact.ToJSONRepresentation());
Console.ReadKey();
}
}
}
The result:
{
"id": 1,
"name": "Ayrton Senna",
"addresses": [
{
"id": 1,
"streetAddress": "Rua Dr. Fernandes Coelho, 85",
"complement": "15º andar",
"city": "São Paulo",
"province": "São Paulo",
"country": "Brazil",
"postalCode": "05423040"
},
{
"id": 2,
"streetAddress": "Avenida Senador Teotônio Vilela, 241",
"complement": null,
"city": "São Paulo",
"province": "São Paulo",
"country": "Brazil",
"postalCode": null
}
]
}
Now I will implement the constructor method that will receives a JSON string and populates the class' fields.
A new JSON serializer is available in the System.Text.Json namespace. It's included in the .NET Core 3.0 shared framework and is in a NuGet package for projects that target .NET Standard or .NET Framework or .NET Core 2.x.
Example code:
using System;
using System.Text.Json;
public class MyDate
{
public int year { get; set; }
public int month { get; set; }
public int day { get; set; }
}
public class Lad
{
public string FirstName { get; set; }
public string LastName { get; set; }
public MyDate DateOfBirth { get; set; }
}
class Program
{
static void Main()
{
var lad = new Lad
{
FirstName = "Markoff",
LastName = "Chaney",
DateOfBirth = new MyDate
{
year = 1901,
month = 4,
day = 30
}
};
var json = JsonSerializer.Serialize(lad);
Console.WriteLine(json);
}
}
In this example the classes to be serialized have properties rather than fields; the System.Text.Json serializer currently doesn't serialize fields.
Documentation: