how to retrieve count of different object types from JSON string in c#

Question

I have a single array json string containing data:

[{"Name":"John","Age":"22"}, {"Name":"Jack","Age":"56"}, {"Name":"John","Age":"82"}, {"Name":"Jack","Age":"95"}]

I have deserialized the data and have successfully written the data to jquery datatables. However i would now like to add a column in the datatable to contain the count of names that are john and names that are jack all in one column. I can get the individual counts by saying the following in a loop:

if (people[i].Name == "John")
   {
                name_count++;
   }
if (people[i].Name == "Jack")
   {
          name_count2++;
   }

How do i get this data to display in One Column that matches either the row containing the name jack or john? I am using C#. Thanks in advance

Answer 1

I would suggest using underscore.js (http://documentcloud.github.com/underscore). You can easily achieve any sort of map/reduce/select you want. Here an example:

var people = [{"Name":"John","Age":"22"}, {"Name":"Jack","Age":"56"}, {"Name":"John","Age":"82"}, {"Name":"Jack","Age":"95"}];

var num_johns = _(people).select(function(obj){ 
    return obj.Name === 'John'}).length;

alert(num_johns); //alerts 2

You can even go a step further and factor out the select function with some currying http://www.dustindiaz.com/javascript-curry/ - depends on what your exact problem is.

Answer 2

You could do some linq grouping against the array

    var peeps = from person in people 
        group person by person.name into bucket 
        select new { name = bucket.Key, count = bucket.Count() };

This will create an enumerable anonymous type with name and count properties that you can iterate over to get the name and count of the names, eg :

class Guy
    {
        public int age; public string name;
        public Guy( int age, string name ) {
            this.age = age;
            this.name = name;
        }

    }

    class Program
    {
        static void Main( string[] args ) {
            var GuyArray = new Guy[] { 
            new Guy(22,"John"),new Guy(25,"John"),new Guy(27,"John"),new Guy(29,"John"),new Guy(12,"Jack"),new Guy(32,"Jack"),new Guy(52,"Jack"),new Guy(100,"Abe")};

        var peeps = from f in GuyArray group f by f.name into g select new { name = g.Key, count = g.Count() };

            foreach ( var record in peeps ) {
                Console.WriteLine( record.name + " : " + record.count );
            }

        }
    }

Will emit:

John : 4
Jack : 3
Abe : 1