FormData append item in array

If your using FormData to send the data, you need to .append() each individual name/value to FormData. Since its a collection, you must include the collection indexer (which must be zero based and consecutive), for example

formData.append("Regions[0].Id", someValue);formData.append("Regions[0].Name", someValue);formData.append("Regions[1].Id", someValue);formData.append("Regions[1].Name", someValue);

Since your doing this in a loop, you can use

for (var i = 0; i < region.length; i++) {    formData.append("Regions[" + i + "].Id", region[i])}

 var regionList = [];    for (var i = 0; i < region.length; i++) {        var item = {            Id: region[i].Id,            Name : region[i].Name,        }        regionList.push(item);    }    regionList = JSON.stringify({ "item": regionList });//Here "item" name should match the parameter name in your Action method name in controller (item in your case.)

Then pass the regionList object to $.ajax as data.

 $.ajax({            type: 'POST',            url: '@Url.Action("AddByRegion", "News")',            data: regionList,            contentType: false,            processData: false,            ....        });