ruby on rails - Updating Cart content based on option selected -

while implementing cart, want allow user change quantity of item has in cart. right now, have select tag display quantity, correct quantity pre-selected. want this: user selects option in select tag, quantity in cart updated. how should proceed? right quantity displayed follows:

<%= form_tag %>     <%= select_tag "quantity", options_for_select((1..item.quantity).to_a, quantity) %> <% end %> 

one more thing. show_cart partial doesn't include checkout button, if that's of help.

this can achieve through ajax. need execute jquery whenever user selects value of <select> tag.

let's select_tag generate following <select> tag in html:

<select id="quantityoptions">   <option value="1">one item</option>   <option value="2">two items</option>   <option value="3">three items</option>   <option value="4">four items</option> </select>  

in javascript file, need .change() event, , write ajax call in it.

$("#quantityoptions").change(function() {     var currentquantity = $(this).val(); // give currenlty selected option in <select> tag     $.ajax(         method: "post",          url: http://localhost:3000/update_quantity, // or whatever custom url have built         data: { val: currentquantity },         success: function() {             console.log("the value reached on server");         }      ); }); 

sure, refine more; idea of it. , don't forget have authentication on server, may need attach request token each request.