[FIX] web: list: m2o doesn't trigger fieldChange when empty

Gives time to the user to enter an actual value in m2o in list views.

Before this commit, emptying a many2one field (selecting all > BACKSPACE or DELETE)
triggered instantly a field_change. This was an issue in multi edition as a field
changed triggered instantly a save on selected records without giving time to the
user to enter a new value.

Now, many2ones only trigger a fieldChange when selecting a new valid value.

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

@@ -600,8 +600,10 @@ var FieldMany2One = AbstractField.extend({
             no_create: !self.can_create,
             on_selected: function (records) {
                 self.reinitialize(records[0]);
+            },
+            on_closed: function () {
                 self.activate();
-            }
+            },
         })).open();
     },
     /**
@@ -770,6 +772,22 @@ var ListFieldMany2One = FieldMany2One.extend({
         'focusin input': '_onInputFocusin',
     }),
 
+    /**
+     * Should never be allowed to be opened while in readonly mode in a list
+     *
+     * @override
+     */
+    init: function () {
+        this._super.apply(this, arguments);
+        // when we empty the input, we delay the setValue to prevent from
+        // triggering the 'fieldChanged' event twice when the user wants set
+        // another m2o value ; the following attribute is used to determine when
+        // we skipped the setValue, s.t. we can perform it later on if the user
+        // didn't select another value
+        this.mustSetValue = false;
+        this.m2oDialogFocused = false;
+    },
+
     //--------------------------------------------------------------------------
     // Public
     //--------------------------------------------------------------------------
@@ -785,6 +803,13 @@ var ListFieldMany2One = FieldMany2One.extend({
         }
         return this._super.apply(this, arguments);
     },
+    /**
+     * @override
+     */
+    reinitialize: function () {
+        this.mustSetValue = false;
+        return this._super.apply(this, arguments);
+    },
 
     //--------------------------------------------------------------------------
     // Private
@@ -796,6 +821,52 @@ var ListFieldMany2One = FieldMany2One.extend({
     _renderReadonly: function () {
         this.$el.text(this.m2o_value);
     },
+    /**
+     * @override
+     * @private
+     */
+    _searchCreatePopup: function () {
+        this.m2oDialogFocused = true;
+        return this._super.apply(this, arguments);
+    },
+
+    //--------------------------------------------------------------------------
+    // Handlers
+    //--------------------------------------------------------------------------
+
+    /**
+     * @private
+     */
+    _onInputFocusin: function () {
+        this.m2oDialogFocused = false;
+    },
+    /**
+     * In list views, we don't want to try to trigger a fieldChange when the field
+     * is being emptied. Instead, it will be triggered as the user leaves the field
+     * while it is empty.
+     *
+     * @override
+     * @private
+     */
+    _onInputFocusout: function () {
+        this._super.apply(this, arguments);
+        if (!this.m2oDialogFocused && this.$input.val() === "" && this.mustSetValue) {
+            this.reinitialize(false);
+        }
+    },
+    /**
+     * Prevents the triggering of an immediate _onFieldChanged when emptying the field.
+     *
+     * @override
+     * @private
+     */
+    _onInputKeyup: function () {
+        if (this.$input.val() !== "") {
+            this._super.apply(this, arguments);
+        } else {
+            this.mustSetValue = true;
+        }
+    },
 });
 
 var KanbanFieldMany2One = AbstractField.extend({

addons/web/static/src/js/views/view_dialogs.js

@@ -328,6 +328,7 @@ var SelectCreateDialog = ViewDialog.extend({
         this._super.apply(this, arguments);
         _.defaults(this.options, { initial_view: 'search' });
         this.on_selected = this.options.on_selected || (function () {});
+        this.on_closed = this.options.on_closed || (function () {});
         this.initialIDs = this.options.initial_ids;
     },
 
@@ -411,6 +412,10 @@ var SelectCreateDialog = ViewDialog.extend({
             return fragment;
         });
     },
+    close: function () {
+        this._super.apply(this, arguments);
+        this.on_closed();
+    },
     create_edit_record: function () {
         var self = this;
         var dialog = new FormViewDialog(this, _.extend({}, this.options, {

addons/web/static/tests/fields/relational_fields/field_many2one_tests.js

@@ -566,6 +566,81 @@ QUnit.module('fields', {}, function () {
             form.destroy();
         });
 
+        QUnit.test("many2one doesn't trigger field_change when being emptied", async function (assert) {
+            assert.expect(2);
+
+            const list = await createView({
+                arch: `
+                    <tree editable="top">
+                        <field name="trululu"/>
+                    </tree>`,
+                data: this.data,
+                model: 'partner',
+                View: ListView,
+            });
+
+            // Select two records
+            await testUtils.dom.click(list.$('.o_data_row:eq(0) .o_list_record_selector input'));
+            await testUtils.dom.click(list.$('.o_data_row:eq(1) .o_list_record_selector input'));
+
+            await testUtils.dom.click(list.$('.o_data_row:first() .o_data_cell:first()'));
+
+            const $input = list.$('.o_field_widget[name=trululu] input');
+
+            await testUtils.fields.editInput($input, "");
+            await testUtils.dom.triggerEvents($input, ['keyup']);
+
+            assert.containsNone(document.body, '.modal',
+                "No save should be triggered when removing value");
+
+            await testUtils.fields.many2one.clickOpenDropdown('trululu');
+            await testUtils.fields.many2one.clickHighlightedItem('trululu');
+
+            assert.containsOnce(document.body, '.modal',
+                "Saving should be triggered when selecting a value");
+            await testUtils.dom.click($('.modal .btn-primary'));
+
+            list.destroy();
+        });
+
+        QUnit.test("focus tracking on a many2one in a list", async function (assert) {
+            assert.expect(4);
+
+            const list = await createView({
+                arch: '<tree editable="top"><field name="trululu"/></tree>',
+                archs: {
+                    'partner,false,form': '<form string="Partners"><field name="foo"/></form>',
+                },
+                data: this.data,
+                model: 'partner',
+                View: ListView,
+            });
+
+            // Select two records
+            await testUtils.dom.click(list.$('.o_data_row:eq(0) .o_list_record_selector input'));
+            await testUtils.dom.click(list.$('.o_data_row:eq(1) .o_list_record_selector input'));
+
+            await testUtils.dom.click(list.$('.o_data_row:first() .o_data_cell:first()'));
+
+            const input = list.$('.o_data_row:first() .o_data_cell:first() input')[0];
+
+            assert.strictEqual(document.activeElement, input, "Input should be focused when activated");
+
+            await testUtils.fields.many2one.clickOpenDropdown('trululu');
+            await testUtils.fields.many2one.clickItem('trululu', 'Create');
+
+            // At this point, if the focus is correctly registered by the m2o, there
+            // should be only one modal (the "Create" one) and none for saving changes.
+            assert.containsOnce(document.body, '.modal', "There should be only one modal");
+
+            await testUtils.dom.click($('.modal .btn:not(.btn-primary)'));
+
+            assert.strictEqual(document.activeElement, input, "Input should be focused after dialog closes");
+            assert.strictEqual(input.value, "", "Input should be empty after discard");
+
+            list.destroy();
+        });
+
         QUnit.test('many2one fields with option "no_open"', async function (assert) {
             assert.expect(3);