[FIX] web: allow edition of one2many with widget many2many

It is quite rare, but it happens that a one2many field has to be edited
with a many2many widget: it allows the fact that records are directly
created, and only later linked to the main record.  But the BasicModel
only used the field type to determine which commands it had to send.

In this commit, we introduce a magic flag _forceM2MLink, which, if set
to true, tells the BasicModel to treat the field as a many2many.

1 files changed, 4 insertions, 1 deletions

diff --git a/addons/web/static/src/js/views/basic/basic_model.js b/addons/web/static/src/js/views/basic/basic_model.js
index 04c80764e00..8afd87aedfe 100644
--- a/addons/web/static/src/js/views/basic/basic_model.js
+++ b/addons/web/static/src/js/views/basic/basic_model.js
@@ -361,6 +361,7 @@ var BasicModel = AbstractModel.extend({
 
         delete element._cache;
         delete element._changes;
+        delete element._forceM2MLink;
         delete element.static;
         delete element.parentID;
         delete element.relation_field;
@@ -1141,6 +1142,8 @@ var BasicModel = AbstractModel.extend({
                 list._changes.push(newRecord.id);
                 break;
             case 'ADD_M2M':
+                // force to use link command instead of create command
+                list._forceM2MLink = true;
                 // handle multiple add: command[2] may be a dict of values (1
                 // record added) or an array of dict of values
                 var data = _.isArray(command.ids) ? command.ids : [command.ids];
@@ -1576,7 +1579,7 @@ var BasicModel = AbstractModel.extend({
                 relIds = _.pluck(relData, 'res_id');
                 commands[fieldName] = [];
 
-                if (type === 'many2many') {
+                if (type === 'many2many' || list._forceM2MLink) {
                     // deliberately generate a single 'replace' command instead
                     // of a 'delete' and a 'link' commands with the exact diff
                     // because 1) performance-wise it doesn't change anything