[FIX] web: external button in many2one field

The goal of this commit is to fix two problems in the Many2one field:
1. At setup, the field is considered to be isFloating when its value is false.
2. When "xxx" is encoded and "Create xxx" is selected, the field is still
   considered to be isFloating even the selection.

isFloating should only be true when the user is performing a search, when
they have made their choice isFloating should be set to false.

These problems should result in the external button not being displayed
in these two cases. Currently, the button is displayed correctly due to
a bug in owl. The bug in owl causes all Components that have executed
evaluateExpr with record.evalContext will be render each time record.update
is called. For example, for Many2oneField, it is the call to dynamic.context
in extractProps that will cause the rendering of the Component Field
containing Many2oneField. This will trigger a call to onWillUpdateProps
each time record.update is called, and will modify isFloating to make it correct.
In order to fix OWL without introducing any bugs, we're going to fix these problems.

How to reproduce after OWL is fixed:
====================================

Case 1:
------
- Go to a form view with an field "x" (with an onchange) and a many2one field
- Create a new record (the many2one field is empty)
- Edit field "x"
- The onChange returns a value for the many2one

Before this commit:
    The external button is not displayed

After this commit
    The external button is displayed.

Case 2:
------
- Go to a form view with a many2one field
- Insert "blabla" in the many2one
- Click on "Create blabla".

Before this commit:
    The external button is not displayed

After this commit
    The external button is displayed.

closes odoo/odoo#137212

Signed-off-by: Aaron Bohy (aab) <aab@odoo.com>

addons/web/static/src/views/fields/many2one/many2one_field.js

@@ -104,7 +104,7 @@ export class Many2OneField extends Component {
         };
 
         this.state = useState({
-            isFloating: !this.value,
+            isFloating: false,
         });
         this.computeActiveActions(this.props);
 
@@ -137,6 +137,7 @@ export class Many2OneField extends Component {
                 if (params.triggeredOnBlur) {
                     return this.openConfirmationDialog(name);
                 }
+                this.state.isFloating = false;
                 return this.updateRecord([false, name]);
             };
         }
@@ -146,8 +147,6 @@ export class Many2OneField extends Component {
         };
 
         onWillUpdateProps(async (nextProps) => {
-            this.state.isFloating =
-                "value" in nextProps ? !nextProps.value : !nextProps.record.data[nextProps.name];
             this.computeActiveActions(nextProps);
         });
     }

addons/web/static/tests/views/fields/many2one_field_tests.js

@@ -741,7 +741,7 @@ QUnit.module("Fields", (hooks) => {
             const input = target.querySelector(".o_field_widget[name=user_id] input");
             await editInput(input, null, "yy");
             await clickOpenedDropdownItem(target, "user_id", 'Create "yy"');
-
+            assert.containsOnce(target, ".o_external_button");
             assert.verifySteps(["name_create"]);
         }
     );
@@ -4487,4 +4487,32 @@ QUnit.module("Fields", (hooks) => {
             "aaa"
         );
     });
+
+    QUnit.test(
+        "external button must be displayed after the update caused by an onchange",
+        async function (assert) {
+            serverData.models.partner.onchanges = {
+                display_name: function (obj) {
+                    if (obj.display_name) {
+                        obj.trululu = 1;
+                    }
+                },
+            };
+            await makeView({
+                type: "form",
+                resModel: "partner",
+                serverData,
+                arch: `
+            <form>
+                <field name="display_name"/>
+                <field name="trululu"/>
+            </form>`,
+            });
+
+            assert.containsNone(target, ".o_external_button");
+
+            await editInput(target, "[name=display_name] input", "new value");
+            assert.containsOnce(target, ".o_external_button");
+        }
+    );
 });