Reading JSON files with C# and JSON.net

Question

Im having some trouble to understand how to use JSON.net to read a json file.

The file is looking like this:

"version": {   
    "files": [
        {
            "url": "http://www.url.com/",
            "name": "someName"
        },
        { 
            "name": "someOtherName"
            "url": "http://www.url.com/"
            "clientreq": true
        }, ....

I really do not have much idea how i can read this file .. What i need to do is to read the lines and download the file via the "url".. I know how to download files and so on, but i dont know how i can use JSON.net to read the json file and loop through each section, and download the file..

Can you assist ?

Esteban Elverdin · Accepted Answer · 2013-12-05 14:16:30Z

9

The easiest way is to deserialize your json into a dynamic object like this

Then you can access its properties an loop for getting the urls

dynamic result = Newtonsoft.Json.JsonConvert.DeserializeObject(jsonString);

var urls = new List<string>();

foreach(var file in result.version.files)
{
    urls.Add(file.url); 
}

edited Dec 5, 2013 at 14:16

answered Oct 25, 2013 at 17:38

Esteban Elverdin

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1 Comment

Daniel Jørgensen Over a year ago

I ended up using this method as it looked the most simple which seems to work! Thanks a bunch. For info i used streamreader to read the contents of the file with readtoend, which i then used as the "jsonString"

Tim S. · Accepted Answer · 2013-10-25 17:45:27Z

6

http://json2csharp.com/ helps you create C# classes based on your JSON data type. Once you have your classes to match your data, you can deserialize with Json.NET and then work with your data:

var myMessage = JsonConvert.DeserializeObject<MyMessage>(myString);
foreach (var file in myMessage.Version.Files)
{
    // download file.Url
}

Or you can access it as a dynamic object:

dynamic myMessage = JsonConvert.DeserializeObject(myString);
foreach (var file in myMessage.version.files)
{
    // download file.url
}

If you use classes, they might be:

public class File
{
    public Uri Url { get; set; }
    public string Name { get; set; }
    public bool? ClientReq { get; set; }
}

public class Version
{
    public IList<File> Files { get; set; }
}

public class MyMessage
{
    public Version Version { get; set; }
}

(note that Json.Net is smart enough to map properties where the case is different, and turn the URLs into Uri objects) It works when the string is like:

string myString = @"{""version"": {   
    ""files"": [
        {
            ""url"": ""http://www.url.com/"",
            ""name"": ""someName""
        },
        { 
            ""name"": ""someOtherName"",
            ""url"": ""http://www.url.com/"",
            ""clientreq"": true
        }]}}";

edited Oct 25, 2013 at 17:45

answered Oct 25, 2013 at 17:40

Tim S.

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4 Comments

Esteban Elverdin Over a year ago

"note that Json.Net is smart enough to map properties where the case is different" that's not exactly true, you need to use a CamelCasePropertyNamesContractResolver for that.

Tim S. Over a year ago

@EstebanElverdin it seems to do that by default, then, because the code I've got works, (which maps clientreq to ClientReq) without explicitly specifying any contract resolver.

Esteban Elverdin Over a year ago

yes, you are right, no need to do it in your example, I will review some code I was working and see why it does not did it by default.

Family Over a year ago

Thanks for the link to json2csharp.com I can see myself using that a lot. Would have taken me ages to work the structure out by myself.

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