Do not force value for single list on multi-value field

Fields based on multi-value must not be forced to the single value of a list.

Closes #12737

sao/src/common.js

@@ -2755,12 +2755,12 @@
             }
             return this.simplify(this.merge(result));
         },
-        unique_value: function(domain) {
+        unique_value: function(domain, single_value=true) {
             if ((domain instanceof Array) &&
                     (domain.length == 1)) {
                 let [name, operator, value, ...model] = domain[0];
                 if (operator == '=' ||
-                    (operator == 'in' && value.length == 1)) {
+                    (single_value && operator == 'in' && value.length == 1)) {
                     value = operator == '=' ? value : value[0];
                     var count = 0;
                     if (model.length && name.endsWith('.id')) {

sao/src/model.js

@@ -1556,6 +1556,7 @@
 
     Sao.field.Field = Sao.class_(Object, {
         _default: null,
+        _single_value: true,
         init: function(description) {
             this.description = description;
             this.name = description.name;
@@ -1728,12 +1729,13 @@
             } else {
                 let [screen_domain, _] = this.get_domains(
                     record, pre_validate);
-                var uniques = inversion.unique_value(domain);
+                var uniques = inversion.unique_value(
+                    domain, this._single_value);
                 var unique = uniques[0];
                 var leftpart = uniques[1];
                 var value = uniques[2];
                 let unique_from_screen = inversion.unique_value(
-                    screen_domain)[0];
+                    screen_domain, this._single_value)[0];
                 if (this._is_empty(record) &&
                     !is_required &&
                     !is_invisible &&
@@ -1821,6 +1823,7 @@
 
     Sao.field.MultiSelection = Sao.class_(Sao.field.Selection, {
         _default: null,
+        _single_value: false,
         get: function(record) {
             var value = Sao.field.MultiSelection._super.get.call(this, record);
             if (jQuery.isEmptyObject(value)) {
@@ -2203,6 +2206,7 @@
             Sao.field.One2Many._super.init.call(this, description);
         },
         _default: null,
+        _single_value: false,
         _set_value: function(record, value, default_, modified) {
             this._set_default_value(record);
             var group = record._values[this.name];
@@ -2813,6 +2817,7 @@
 
     Sao.field.Dict = Sao.class_(Sao.field.Field, {
         _default: {},
+        _single_value: false,
         init: function(description) {
             Sao.field.Dict._super.init.call(this, description);
             this.schema_model = new Sao.Model(description.schema_model);

sao/src/view/tree.js

@@ -879,11 +879,13 @@
                     visible_columns -= 1;
                     column.set_visible(false);
                 } else {
+                    const field = this.screen.model.fields[name];
                     var inv_domain = inversion.domain_inversion(domain, name);
                     if (typeof inv_domain != 'boolean') {
                         inv_domain = inversion.simplify(inv_domain);
                     }
-                    var unique = inversion.unique_value(inv_domain)[0];
+                    var unique = inversion.unique_value(
+                        inv_domain, field._single_value)[0];
                     if (unique && jQuery.isEmptyObject(this.children_field)) {
                         visible_columns -= 1;
                         column.set_visible(false);

sao/tests/sao.js

@@ -2813,6 +2813,7 @@
         QUnit.ok(compare(unique_value(domain), [false, null, null]));
         domain = [['a', 'in', [1]]];
         QUnit.ok(compare(unique_value(domain), [true, 'a', 1]));
+        QUnit.ok(compare(unique_value(domain, false), [false, null, null]));
         domain = [['a', 'in', [1, 2]]];
         QUnit.ok(compare(unique_value(domain), [false, null, null]));
         domain = [['a', 'in', []]];

tryton/tryton/common/domain_inversion.py

@@ -424,13 +424,14 @@ def concat(*domains, **kwargs):
     return simplify(merge(result))
 
 
-def unique_value(domain):
+def unique_value(domain, single_value=True):
     "Return if unique, the field and the value"
     if (isinstance(domain, list)
             and len(domain) == 1):
         name, operator, value, *model = domain[0]
-        if operator == '=' or (operator == 'in' and len(value) == 1):
-            value = value if operator == '=' else value[0]
+        if (operator == '='
+                or (single_value and operator == 'in' and len(value) == 1)):
+            value = value if operator == '=' and single_value else value[0]
             count = 0
             if model and name.endswith('.id'):
                 count = 1

tryton/tryton/gui/window/view_form/model/field.py

@@ -30,6 +30,7 @@ class Field(object):
     set_client: save the value from the widget
     '''
     _default = None
+    _single_value = True
 
     @staticmethod
     def get_field(ctype):
@@ -111,8 +112,10 @@ class Field(object):
             invalid = 'domain'
         else:
             screen_domain, _ = self.domains_get(record, pre_validate)
-            unique, leftpart, value = unique_value(domain)
-            unique_from_screen, _, _ = unique_value(screen_domain)
+            unique, leftpart, value = unique_value(
+                domain, single_value=self._single_value)
+            unique_from_screen, _, _ = unique_value(
+                screen_domain, single_value=self._single_value)
             if (self._is_empty(record)
                     and not is_required
                     and not is_invisible
@@ -248,6 +251,7 @@ class SelectionField(Field):
 class MultiSelectionField(SelectionField):
 
     _default = None
+    _single_value = False
 
     def get(self, record):
         value = super().get(record)
@@ -601,6 +605,7 @@ class O2MField(Field):
     '''
 
     _default = None
+    _single_value = False
 
     def __init__(self, attrs):
         super(O2MField, self).__init__(attrs)
@@ -1112,6 +1117,7 @@ class BinaryField(Field):
 class DictField(Field):
 
     _default = {}
+    _single_value = False
 
     def __init__(self, attrs):
         super(DictField, self).__init__(attrs)

tryton/tryton/gui/window/view_form/view/list.py

@@ -1132,10 +1132,12 @@ class ViewTree(View):
             elif name == self.screen.exclude_field:
                 column.set_visible(False)
             else:
+                field = self.group.fields.get(name)
                 inv_domain = domain_inversion(domain, name)
                 if not isinstance(inv_domain, bool):
                     inv_domain = simplify(inv_domain)
-                unique, _, _ = unique_value(inv_domain)
+                unique, _, _ = unique_value(
+                    inv_domain, single_value=field._single_value)
                 column.set_visible(not unique or bool(self.children_field))
         if self.children_field:
             for i, column in enumerate(self.treeview.get_columns()):

trytond/trytond/tests/test_tools.py

@@ -830,6 +830,8 @@ class DomainInversionTestCase(unittest.TestCase):
 
         domain = [['a', 'in', [1]]]
         self.assertEqual(unique_value(domain), (True, 'a', 1))
+        self.assertEqual(
+            unique_value(domain, single_value=False), (False, None, None))
 
         domain = [['a', 'in', [1, 2]]]
         self.assertEqual(unique_value(domain), (False, None, None))

trytond/trytond/tools/domain_inversion.py

@@ -424,12 +424,13 @@ def concat(*domains, **kwargs):
     return simplify(merge(result))
 
 
-def unique_value(domain):
+def unique_value(domain, single_value=True):
     "Return if unique, the field and the value"
     if (isinstance(domain, list)
             and len(domain) == 1):
         name, operator, value, *model = domain[0]
-        if operator == '=' or (operator == 'in' and len(value) == 1):
+        if (operator == '='
+                or (single_value and operator == 'in' and len(value) == 1)):
             value = value if operator == '=' else value[0]
             count = 0
             if model and name.endswith('.id'):