JQuery select2 reformats <select> but instead of parameter id instead of value

I am using select2 jquery plugin to reformat my long selection options. Everything works as expected, except when I submit the form, the value is idsaved as a value instead of a value (in this case lang). I cannot understand what I am doing wrong.

Here's the script:

var langs=[{id:0,lang:'English'},
    {id:1,lang:'Afrikaans'},
    {id:2,lang:'Albanian'},
    {id:3,lang:'Zulu'}];

function format(item) { return item.lang; };

$("#field_4").select2({
                  placeholder: "Select your language",
                  data:{ results: langs, text: 'lang' },
                  formatSelection: format,
                  formatResult: format
                  });

Here's the markup:

<input id="field_4" name="field_4" type="text" class="regular-text " value="3" />

When I register the return value in the console, I see the following:

{Object}
    O: Object
        id: "1"
        text: "Afrikaans"

UPDATE: . - ( select2), ( id). , <select>, AJAX .

id : function(object) {
return object.lang;
}