[FIX] web: properly handles dirty data in form views

Before this commit, we only consider the BasicModel point of view to
determine if a record is dirty.  It is good when we want to determine if
it is actually necessary to save the data, but not correct when we want
to know if some changes can be discarded.

With this commit, the form controller keeps track of its 'dirty' state,
coming from user interactions.  It uses this flag to determine if
changes can be discarded.

addons/web/static/src/js/views/basic/basic_controller.js

@@ -33,6 +33,7 @@ return AbstractController.extend(FieldManagerMixin, {
         this.hasButtons = params.hasButtons;
         FieldManagerMixin.init.call(this, this.model);
         this.handle = params.initialState.id;
+        this.isDirty = false;
     },
     /**
      * @override
@@ -148,6 +149,18 @@ return AbstractController.extend(FieldManagerMixin, {
     // Handlers
     //--------------------------------------------------------------------------
 
+    /**
+     * We need to keep manually track of the isDirty property.  Note that it is
+     * not the same as the one from the basic model.  A new record from the
+     * basic model is considered dirty, but from the controller point of view,
+     * there was no user interaction and should not be dirty.
+     *
+     * @private
+     */
+    _onFieldChanged: function () {
+        this.isDirty = true;
+        FieldManagerMixin._onFieldChanged.apply(this, arguments);
+    },
     /**
      * When a reload event triggers up, we need to reload the full view.
      * For example, after a form view dialog saved some data.

addons/web/static/src/js/views/form/form_controller.js

@@ -267,7 +267,7 @@ var FormController = BasicController.extend({
      *   can be discarded.  If it has been rejected, then we cannot discard.
      */
     _canBeDiscarded: function () {
-        if (!this.model.isDirty(this.handle)) {
+        if (!this.isDirty) {
             return $.when();
         }
         var message = _t("The record has been modified, your changes will be discarded. Are you sure you want to leave this page ?");
@@ -452,6 +452,7 @@ var FormController = BasicController.extend({
         var self = this;
         this.model.duplicateRecord(this.handle)
             .then(function (handle) {
+                self.isDirty = false;
                 self.handle = handle;
                 self._updateEnv();
                 self._toEditMode();

addons/web/static/test/views/form_tests.js

@@ -1228,6 +1228,58 @@ QUnit.module('Views', {
         form.destroy();
     });
 
+    QUnit.test('discard changes on a new (non dirty, except for defaults) form view', function (assert) {
+        assert.expect(2);
+
+        this.data.partner.fields.foo.default = "ABC";
+
+        var form = createView({
+            View: FormView,
+            model: 'partner',
+            data: this.data,
+            arch: '<form string="Partners"><field name="foo"></field></form>',
+        });
+
+        // switch to edit mode and edit the foo field
+        form.$buttons.find('.o_form_button_edit').click();
+        assert.strictEqual(form.$('.o_form_input').val(), 'ABC', 'input should contain ABC');
+
+        form.$buttons.find('.o_form_button_cancel').click();
+
+        assert.strictEqual($('.modal').length, 0,
+            'there should not be a confirm modal');
+
+        form.destroy();
+    });
+
+    QUnit.test('discard changes on a duplicated record', function (assert) {
+        assert.expect(2);
+
+        var form = createView({
+            View: FormView,
+            model: 'partner',
+            data: this.data,
+            arch: '<form string="Partners"><field name="foo"></field></form>',
+            res_id: 1,
+            viewOptions: {sidebar: true},
+        });
+
+        form.$buttons.find('.o_form_button_edit').click();
+        form.$('input').val("tralala").trigger('input');
+        form.$buttons.find('.o_form_button_save').click();
+
+        form.sidebar.$('a:contains(Duplicate)').click();
+
+        assert.strictEqual(form.$('.o_form_input').val(), 'tralala', 'input should contain ABC');
+
+        form.$buttons.find('.o_form_button_cancel').click();
+
+        assert.strictEqual($('.modal').length, 0,
+            'there should not be a confirm modal');
+
+        form.destroy();
+    });
+
     QUnit.test('switching to another record from a dirty one', function (assert) {
         assert.expect(11);