Creating JSON on the fly with JObject

Question

For some of my unit tests I want the ability to build up particular JSON values (record albums in this case) that can be used as input for the system under test.

I have the following code:

var jsonObject = new JObject();
jsonObject.Add("Date", DateTime.Now);
jsonObject.Add("Album", "Me Against The World");
jsonObject.Add("Year", 1995);
jsonObject.Add("Artist", "2Pac");

This works fine, but I have never really like the "magic string" syntax and would prefer something closer to the expando-property syntax in JavaScript like this:

jsonObject.Date = DateTime.Now;
jsonObject.Album = "Me Against The World";
jsonObject.Year = 1995;
jsonObject.Artist = "2Pac";

You should get double points for the artist / album selection! — spottedmahn
– spottedmahn, Commented Aug 24, 2018 at 20:08

Dimitar Dimitrov · Accepted Answer · 2013-08-15 05:34:37Z

204

Well, how about:

dynamic jsonObject = new JObject();
jsonObject.Date = DateTime.Now;
jsonObject.Album = "Me Against the world";
jsonObject.Year = 1995;
jsonObject.Artist = "2Pac";

answered Aug 15, 2013 at 5:34

Dimitar Dimitrov

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9 Comments

Karl Anderson Over a year ago

Perfect! Exactly what I was looking for, completely forgot about dynamic.

BornToCode Over a year ago

I get 'Newtonsoft.Json.Linq.JObject' does not contain a definition for 'Date' error when I try to run your code. The way I could make it work is change the first line to: dynamic jsonExpando = new ExpandoObject(); and add a line after your code: JObject jsonObject = JObject.FromObject(jsonExpando);

Steve Smith Over a year ago

If you want to add a List<> to your Json object, you need to do something like jsonObject.list = JToken.FromObject(mylist);.

PAS Over a year ago

You could use combination of index and property notation in case you hit field name having special character e.g. Create-Year". You will not b able to write jsonObject.Create-Year = 1995, but can use following. jsonObject["Create-Year"] = 1995; jsonObject.Artist = "2Pac";

Yola Over a year ago

Now instead of magic strings you have magic properties :)

|

Lee Jensen · Accepted Answer · 2015-01-05 18:04:26Z

106

You can use the JObject.Parse operation and simply supply single quote delimited JSON text.

JObject  o = JObject.Parse(@"{
  'CPU': 'Intel',
  'Drives': [
    'DVD read/writer',
    '500 gigabyte hard drive'
  ]
}");

This has the nice benefit of actually being JSON and so it reads as JSON.

Or you have test data that is dynamic you can use JObject.FromObject operation and supply a inline object.

JObject o = JObject.FromObject(new
{
    channel = new
    {
        title = "James Newton-King",
        link = "http://james.newtonking.com",
        description = "James Newton-King's blog.",
        item =
            from p in posts
            orderby p.Title
            select new
            {
                title = p.Title,
                description = p.Description,
                link = p.Link,
                category = p.Categories
            }
    }
});

Json.net documentation for serialization

answered Jan 5, 2015 at 18:04

Lee Jensen

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3 Comments

Thomas Over a year ago

JObject.FromObject should be marked as the correct answer. Thanks.

Jatin Sanghvi Over a year ago

I think JObject.FromObject won't work if there are properties with special characters like -.

Abhid Over a year ago

This is a better answer!

Jatin Sanghvi · Accepted Answer · 2018-01-13 01:32:08Z

81

Neither dynamic, nor JObject.FromObject solution works when you have JSON properties that are not valid C# variable names e.g. "@odata.etag". I prefer the indexer initializer syntax in my test cases:

JObject jsonObject = new JObject
{
    ["Date"] = DateTime.Now,
    ["Album"] = "Me Against The World",
    ["Year"] = 1995,
    ["Artist"] = "2Pac"
};

Having separate set of enclosing symbols for initializing JObject and for adding properties to it makes the index initializers more readable than classic object initializers, especially in case of compound JSON objects as below:

JObject jsonObject = new JObject
{
    ["Date"] = DateTime.Now,
    ["Album"] = "Me Against The World",
    ["Year"] = 1995,
    ["Artist"] = new JObject
    {
        ["Name"] = "2Pac",
        ["Age"] = 28
    }
};

With object initializer syntax, the above initialization would be:

JObject jsonObject = new JObject
{
    { "Date", DateTime.Now },
    { "Album", "Me Against The World" },
    { "Year", 1995 }, 
    { "Artist", new JObject
        {
            { "Name", "2Pac" },
            { "Age", 28 }
        }
    }
};

edited Jan 13, 2018 at 1:32

answered Jan 12, 2018 at 13:30

Jatin Sanghvi

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3 Comments

Anthony Brenelière Over a year ago

The last one is definitively the best syntax to write json in c#.

kofifus Over a year ago

see stackoverflow.com/questions/51015036/… for how to do this with collections as well

nawfal Over a year ago

@AnthonyBrenelière I find the index initializer syntax a lot more clearer. For e.g. this { "Album", "Me Against The World" } in the object initializer looks like a collection of items.

Daniele D. · Accepted Answer · 2016-05-12 23:32:14Z

42

There are some environment where you cannot use dynamic (e.g. Xamarin.iOS) or cases in where you just look for an alternative to the previous valid answers.

In these cases you can do:

using Newtonsoft.Json.Linq;

JObject jsonObject =
     new JObject(
             new JProperty("Date", DateTime.Now),
             new JProperty("Album", "Me Against The World"),
             new JProperty("Year", "James 2Pac-King's blog."),
             new JProperty("Artist", "2Pac")
         )

More documentation here: http://www.newtonsoft.com/json/help/html/CreatingLINQtoJSON.htm

answered May 12, 2016 at 23:32

Daniele D.

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Comments

PAS · Accepted Answer · 2021-11-16 15:14:19Z

8

Sooner or later you will have property with a special character. e.g. Create-Date. The hyphen won't be allowed in property name. This will break your code. In such scenario, You can either use index or combination of index and property.

dynamic jsonObject = new JObject();
jsonObject["Create-Date"] = DateTime.Now; //<-Index use
jsonObject.Album = "Me Against the world"; //<- Property use
jsonObject["Create-Year"] = 1995; //<-Index use
jsonObject.Artist = "2Pac"; //<-Property use

edited Nov 16, 2021 at 15:14

answered Mar 21, 2019 at 0:56

PAS

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4 Comments

Enigmativity Over a year ago

How does this answer the question?

PAS Over a year ago

@Enigmativity, The point I am making is, you can use index notation and property notation together. i.e. obj[x] =x1; obj.y = y1 can be used in the same code. The combination of dynamic keyword and index notation answers the questions. No other answer has mentions this. Possibly, this should be comment than a answer.

Enigmativity Over a year ago

I just think that the question is about not using magic strings, but this answer is giving him that.

PAS Over a year ago

@Enigmativity, dynamic keyword just fools the compiler. So it's no different than arbitrary string. object of dynmaic type is not strongly typed. It's just a syntactic sugar. If the underlying object doesn't have property it will failed runtime. but you just cannot use properties if the name of property contains special characters e.g. 99BottlesOfBeer, namespace, It’s-All-Over. So in those cases, we can use indexed properties. Other answer make you think that it's one or other, but you can mix and match property and index.

Manjunath Bilwar · Accepted Answer · 2018-08-29 20:04:56Z

5

Simple way of creating newtonsoft JObject from Properties.

This is a Sample User Properties

public class User
{
    public string Name;
    public string MobileNo;
    public string Address;
}

and i want this property in newtonsoft JObject is:

JObject obj = JObject.FromObject(new User()
{
    Name = "Manjunath",
    MobileNo = "9876543210",
    Address = "Mumbai, Maharashtra, India",
});

Output will be like this:

{"Name":"Manjunath","MobileNo":"9876543210","Address":"Mumbai, Maharashtra, India"}

answered Aug 29, 2018 at 20:04

Manjunath Bilwar

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2 Comments

WalterAgile Over a year ago

Another option (if User definition is not required) is using anonymous types : var obj = JObject.FromObject(new { Name = "Walter", Country = "Peru" });. Reference here

Manjunath Bilwar Mar 10 at 19:30

Yes, that is correct. Can be created using anonymous type. @WalterAgile

BenJammin · Accepted Answer · 2023-02-22 18:49:53Z

0

You could use the nameof expression combined with a model for the structure you're trying to build.

Example:

record RecordAlbum(string Album, string Artist, int Year);

var jsonObject = new JObject
{
    { nameof(RecordAlbum.Album), "Me Against The World" },
    { nameof(RecordAlbum.Artist), "2Pac" },
    { nameof(RecordAlbum.Year), 1995 }
};

As an added benefit to removing the "magic string" aspect - this also will give you a little bit of refactor-ability. You can easily rename any given property name for the record and it should update the value returned by the nameof() expression.

edited Feb 22, 2023 at 18:49

answered Feb 17, 2023 at 15:48

BenJammin

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1 Comment

Alberto Over a year ago

This does not provide an answer to the question. To critique or request clarification from an author, leave a comment below their post. - From Review

shiftlessatol · Accepted Answer · 2024-08-09 17:01:36Z

0

This works well for me

var jsonObject = JObject.FromObject(new Dictionary<string, string>() {
{ "Date",DateTime.Now.ToString() }
,{ "Album", "Me Against The World" }
,{ "Year", "1995" }
,{ "Artist", "2Pac" }
});

JSON is always a string. So creating a Dictionary will naturally convert automagically to JSON when it is parsed out. If you want to make it a JObject, just create the Dictionary in the static method and have it immediately become one. The JObject class will do your conversions as well.

answered Aug 9, 2024 at 17:01

shiftlessatol

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Comments

Nirmal · Accepted Answer · 2013-08-15 05:43:33Z

-4

You can use Newtonsoft library and use it as follows

using Newtonsoft.Json;



public class jb
{
     public DateTime Date { set; get; }
     public string Artist { set; get; }
     public int Year { set; get; }
     public string album { set; get; }

}
var jsonObject = new jb();

jsonObject.Date = DateTime.Now;
jsonObject.Album = "Me Against The World";
jsonObject.Year = 1995;
jsonObject.Artist = "2Pac";


System.Web.Script.Serialization.JavaScriptSerializer oSerializer =
         new System.Web.Script.Serialization.JavaScriptSerializer();

string sJSON = oSerializer.Serialize(jsonObject );

answered Aug 15, 2013 at 5:43

Nirmal

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1 Comment

Mickey Perlstein Over a year ago

you're not actually using the library newtonsoft here

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