Rails 4 - destroy action deletes wrong record - ruby-on-rails

Question

I am doing an ajax request to rails passing in the data an id.
here is the ajax
function delete_availability(id) {
var id = id;
$.ajax({
type: "DELETE",
url: "/events/" + id,
statusCode: {
200: function() {
//alert("200");
},
202: function() {
//alert("202");
}
},
success: function(data) {
console.log('availability deleted');
},
error: function(xhr) {
alert("The error code is: " + xhr.statusText);
}
});
}
my destroy action
def destroy
#event = Event.find_by(params[:id]);
respond_to do |format|
if #event.destroy
format.json {
render json: {}
}
end
end
end
my event model has nothing in it
class Event < ActiveRecord::Base
end
the problem is even though rails receives correct id, when it goes for destroying, it changes id and destroys the next one.
here is the rails log:
Processing by EventsController#destroy as */*
Parameters: {"id"=>"66"}
Event Load (0.1ms) SELECT "events".* FROM "events" WHERE (66) LIMIT 1
(0.0ms) begin transaction
SQL (0.2ms) DELETE FROM "events" WHERE "events"."id" = ? [["id", 65]]
(2.4ms) commit transaction
Completed 200 OK in 6ms (Views: 0.1ms | ActiveRecord: 2.8ms)
anyone knows why?

Answer 1

You should use Event.find(params[:id]) or Event.find_by(id: params[:id]).
What happens with your code is that the SQL query finds every event - WHERE (66) is true for any record - and find_by takes the first record from the set, and it gets destroyed. The ID from the request doesn't matter.

Answer 2

Why you use find_by its used when you want to use with different attribute to search use:
Event.find(params[:id])
OR use find_by_id if you want to not throw an Exception if record not find
Event.find_by_id(params[:id])
OR if you still want to use find_by you can use which if no record is found it returns nil:
Event.find_by(id: params[:id])
and use find_by! to throuw an exception if no record found with this id:
Event.find_by!(id: params[:id])