[FIX] web: FieldMany2One: don't re-render if dirty

The 'main_flow_tour' noticed an error that we
had already corrected for the input fields.
See here: @a71f2237

In fact the same error can occur in the many2one fields
for the exact same reason.
It's why the 'main_flow_tour' crashed at the following step:
".ui-menu-item > a:contains('the_flow.customer')"

addons/web/static/src/js/fields/relational_fields.js

@@ -95,6 +95,7 @@ var FieldMany2One = AbstractField.extend({
     template: 'FieldMany2One',
     custom_events: _.extend({}, AbstractField.prototype.custom_events, {
         'closed_unset': '_onDialogClosedUnset',
+        'field_changed': '_onFieldChanged',
         'quick_create': '_onQuickCreate',
         'search_create_popup': '_onSearchCreatePopup',
     }),
@@ -124,6 +125,12 @@ var FieldMany2One = AbstractField.extend({
         // 'recordParams' is a dict of params used when calling functions
         // 'getDomain' and 'getContext' on this.record
         this.recordParams = {fieldName: this.name, viewType: this.viewType};
+        // We need to know if the widget is dirty (i.e. if the user has changed
+        // the value, and those changes haven't been acknowledged yet by the
+        // environment), to prevent erasing that new value on a reset (e.g.
+        // coming by an onchange on another field)
+        this._isDirty = false;
+        this.lastChangeEvent = undefined;
     },
     start: function () {
         // booleean indicating that the content of the input isn't synchronized
@@ -151,9 +158,31 @@ var FieldMany2One = AbstractField.extend({
      * TODO
      */
     reinitialize: function (value) {
+        this.isDirty = false;
         this.floating = false;
         this._setValue(value);
     },
+    /**
+     * Re-renders the widget if it isn't dirty. The widget is dirty if the user
+     * changed the value, and that change hasn't been acknowledged yet by the
+     * environment. For example, another field with an onchange has been updated
+     * and this field is updated before the onchange returns. Two '_setValue'
+     * are done (this is sequential), the first one returns and this widget is
+     * reset. However, it has pending changes, so we don't re-render.
+     *
+     * @override
+     */
+    reset: function (record, event) {
+        this._reset(record, event);
+        if (!event || event === this.lastChangeEvent) {
+            this.isDirty = false;
+        }
+        if (this.isDirty) {
+            return $.when();
+        } else {
+            return this._render();
+        }
+    },
 
     //--------------------------------------------------------------------------
     // Private
@@ -237,6 +266,16 @@ var FieldMany2One = AbstractField.extend({
     _getDisplayName: function (value) {
         return value.split('\n')[0];
     },
+    /**
+     * Listens to events 'field_changed' to keep track of the last event that
+     * has been trigerred. This allows to detect that all changes have been
+     * acknowledged by the environment.
+     *
+     * @param {OdooEvent} event 'field_changed' event
+     */
+    _onFieldChanged: function (event) {
+        this.lastChangeEvent = event;
+    },
     /**
      * @private
      * @param {string} name
@@ -475,6 +514,7 @@ var FieldMany2One = AbstractField.extend({
      * @private
      */
     _onDialogClosedUnset: function () {
+        this._isDirty = false;
         this.floating = false;
         this._render();
     },
@@ -543,6 +583,7 @@ var FieldMany2One = AbstractField.extend({
             // confirmation that the many2one is not properly set.
             return;
         }
+        this.isDirty = true;
         if (this.$input.val() === "") {
             this.reinitialize(false);
         } else if (this._getDisplayName(this.m2o_value) !== this.$input.val()) {

addons/web/static/tests/fields/relational_fields_tests.js

@@ -6329,6 +6329,63 @@ QUnit.module('relational_fields', {
         form.destroy();
     });
 
+    QUnit.test('one2many field: change value before pending onchange returns', function (assert) {
+        var done = assert.async();
+        assert.expect(2);
+
+        var M2O_DELAY = relationalFields.FieldMany2One.prototype.AUTOCOMPLETE_DELAY;
+        relationalFields.FieldMany2One.prototype.AUTOCOMPLETE_DELAY = 0;
+
+        this.data.partner.onchanges = {
+            int_field: function () {}
+        };
+        var def;
+        var form = createView({
+            View: FormView,
+            model: 'partner',
+            data: this.data,
+            arch:'<form string="Partners">' +
+                    '<field name="p">' +
+                        '<tree editable="bottom">' +
+                            '<field name="int_field"/>' +
+                            '<field name="trululu"/>' +
+                        '</tree>' +
+                    '</field>' +
+                '</form>',
+            mockRPC: function (route, args) {
+                var result = this._super.apply(this, arguments);
+                if (args.method === 'onchange') {
+                    // delay the onchange RPC
+                    return $.when(def).then(_.constant(result));
+                }
+                return result;
+            },
+        });
+
+        form.$('.o_field_x2many_list_row_add a').click();
+        def = $.Deferred();
+        form.$('.o_field_widget[name=int_field]')
+            .val('44')
+            .trigger('input');
+
+        var $dropdown = form.$('.o_field_many2one input').autocomplete('widget');
+        // set trululu before onchange
+        form.$('.o_field_many2one input').val('first').trigger('keydown').trigger('keyup');
+        // complete the onchange
+        def.resolve();
+        assert.strictEqual(form.$('.o_field_many2one input').val(), 'first',
+            'should have kept the new value');
+        concurrency.delay(0).then(function () {
+            // check name_search result
+            assert.strictEqual($dropdown.find('li:not(.o_m2o_dropdown_option)').length, 1,
+                        'autocomplete should contains 1 suggestion');
+
+            relationalFields.FieldMany2One.prototype.AUTOCOMPLETE_DELAY = M2O_DELAY;
+            form.destroy();
+            done();
+        });
+    });
+
     QUnit.test('one2many with default value: edit line to make it invalid', function (assert) {
         assert.expect(3);