Hi everyone! I created a JS button located in the sale order line that call a python method and opens an action as a popup. 

The goal here is that the user can access to that button and do something, the very next moment it clicks on "Add a Line" on a Sale Order.

The issue I'm having is that inside the python method, the sale order line is not created yet and therefore anything I do afterwards is useless.

How can I make sure that when I click the JS button, my Sale Order Line get created before?

This is the event and the call of the js function:

events:_.extend({}, Widget.prototype.events,{'click':'_openBudgetSplit',}),

/**

* @private

* @param{MouseEvent}event

* @returns{Promise} action loaded

*/

async_openBudgetSplit(ev) {

    ev.stopPropagation();

    this.$el.find('.fa-percent').prop('special_click', true);

    var action = awaitthis._rpc({

        model:'sale.order.line',

        method:'action_show_budget_split',

        args: [[this.model.data.id], this.product_id, [this.product]]            });

    return this.do_action(action);

Thanks a lot in advance :)