How to query data from json in c# windows phone -

i new windows phone dev. i'm working on app fetch json web service , parse , display app. used json.net parse it. here's json file:

[ {     "id": "001",     "title": "title1",     "content": "sample content",     "category_id": "3",     "image": "defaultimg.jpg" },  {     "id": "021",     "title": "title2",     "content": "sample content",     "category_id": "1",     "image": "defaultimg2.jpg" },  {     "id": "011",     "title": "title3",     "content": "sample content",     "category_id": "3",     "image": "defaultimg22.jpg" },  {     "id": "008",     "title": "title24",     "content": "sample content",     "category_id": "2",     "image": "defaultimg12.jpg" }, {     "id": "121",     "title": "title12",     "content": "sample content",     "category_id": "3",     "image": "defaultimg27.jpg" } ] 

so came class of json2csharp.com

    public class rootobject {     public string id { get; set; }     public string title { get; set; }     public string content { get; set; }     public string category_id { get; set; }     public string image { get; set; } } 

here's code in cs

 var data = new webclient();             observable               .fromevent<downloadstringcompletedeventargs>(data, "downloadstringcompleted")               .subscribe(r =>               {                   var deserialized =                     jsonconvert.deserializeobject<list<rootobject>>(r.eventargs.result);                   listbox1.itemssource = deserialized;               });             data.downloadstringasync(               new uri("http://sampleurl.com/xyz/myjson.aspx")); 

i want display has "category_id": "9" on listbox1 can me how filter data? im student , new in c# windows phone. thanks!

you want use linq manipulate list<rootobject>, like:

var deserialized = jsonconvert.deserializeobject<list<rootobject>>(r.eventargs.result);  // select rootobjects category_id equal 9 listbox1.itemssource = deserialized.where(r => r.category_id == 9);