[FIX] pad: remove wrong warning at pad creation

When creating a pad before this change these were the steps:

- modify pad URL for new pad URL
- end of record loading

This caused an issue because modifying the record at this point would
mark it as dirty before displaying it (which would result in a erroneous
warning "The record has been modified, your changes will be discarded.
Are you sure you want to leave this page ?").

With this fix:

- modifying the pad URL is done after the record is ready

- deferred have been unified (to remove possible race conditions)

closes #15239
opw-702797

forward port note: this change is needed up to saas-15, over saas-15
only a small part is needed (because x2many views are loaded with the
root view and there is one widget instance per record).

code note: it would be better to modify load_record of form view and
delay `record_loaded` upto after x2many views are loaded, but possible
impacts have been judged too risky so this is done only in pad widget.

1 files changed, 45 insertions, 16 deletions

diff --git a/addons/pad/static/src/js/pad.js b/addons/pad/static/src/js/pad.js
index 30c89d82819..cebe92055a7 100644
--- a/addons/pad/static/src/js/pad.js
+++ b/addons/pad/static/src/js/pad.js
@@ -17,7 +17,9 @@ var FieldPad = form_common.AbstractField.extend(form_common.ReinitializeWidgetMi
             event.preventDefault();
             self.set("configured", true);
         });
-        this.pad_loading_request = null;
+        // CHANGES ONLY NEEDED UNTIL SAAS-15
+        // deferred for request getting pad content (readonly) or new pad url (edit)
+        this._pad_loading_deferred = null;
     },
     initialize_content: function() {
         var self = this;
@@ -36,14 +38,25 @@ var FieldPad = form_common.AbstractField.extend(form_common.ReinitializeWidgetMi
     },
     render_value: function() {
         var self = this;
-        $.when(this._configured_deferred, this.pad_loading_request).always(function() {
+        $.when(this._configured_deferred).always(function() {
             if (!self.get('configured')){
                 return;
             }
+
+            // reject previously ongoing _pad_loading_deferred
+            if (self._pad_loading_deferred !== null) {
+                self._pad_loading_deferred.reject();
+                self.$('.oe_pad_content').removeClass('oe_pad_loading').html('');
+            }
+            self._pad_loading_deferred = $.Deferred();
+            // keep reference to current _pad_loading_deferred
+            var loading_def = self._pad_loading_deferred;
+
             var value = self.get('value');
             if (self.get('effective_readonly')) {
                 if (_.str.startsWith(value, 'http')) {
-                    self.pad_loading_request = self.view.dataset.call('pad_get_content', {url: value}).done(function(data) {
+                    self.view.dataset.call('pad_get_content', {url: value}).then(loading_def.resolve, loading_def.reject);
+                    loading_def.done(function(data) {
                         self.$('.oe_pad_content').removeClass('oe_pad_loading').html('<div class="oe_pad_readonly"><div>');
                         self.$('.oe_pad_readonly').html(data);
                     }).fail(function() {
@@ -54,21 +67,37 @@ var FieldPad = form_common.AbstractField.extend(form_common.ReinitializeWidgetMi
                 }
             }
             else {
-                var def = $.when();
+                var def = $.Deferred();
                 if (! value || !_.str.startsWith(value, 'http')) {
-                    def = self.view.dataset.call('pad_generate_url', {
-                        context: {
-                            model: self.view.model,
-                            field_name: self.name,
-                            object_id: self.view.datarecord.id
-                        },
-                    }).then(function(data) {
-                        if (! data.url) {
-                            self.set("configured", false);
-                        } else {
-                            self.internal_set_value(data.url);
-                        }
+                    var deferreds = [
+                        self.view.dataset.call('pad_generate_url', {
+                            context: {
+                                model: self.view.model,
+                                field_name: self.name,
+                                object_id: self.view.datarecord.id
+                            }
+                        }),
+                        // change record only after record_loaded and its call stack is finished
+                        self.view.record_loaded.then(function() {
+                            var call_stack_ended = $.Deferred();
+                            _.defer(call_stack_ended.resolve);
+                            return call_stack_ended;
+                        })
+                    ];
+                    // delay onchange after x2many views are loaded
+                    deferreds = deferreds.concat(_.compact(_.pluck(self.view.fields, 'is_loaded')));
+                    $.when.apply($, deferreds).then(function(data) {
+                        // update value only if loading_def has not been previously rejected
+                        loading_def.resolve().done(function(){
+                            if (! data.url) {
+                                self.set("configured", false);
+                            } else {
+                                self.internal_set_value(data.url);
+                            }
+                        }).then(def.resolve, def.reject);
                     });
+                } else {
+                    def.resolve();
                 }
                 def.then(function() {
                     value = self.get('value');