[FIX] web: reimplement `group_by_tooltip` option in kanban

This option hadn't been implemented in the new views.
It allows to display informative explanations as tooltips on column over.

It can be set on a many2one field in the kanban view, e.g.:

```<field name="stage_id" options='{"group_by_tooltip":
    {"<tooltipFieldOnStageModel>": "<ABeautifulTitle>"}
}'/>
```

An extra RPC needs to be done on the many2one relation to fetch these additional
fields and the data are stored in the datapoint under the key `tooltipData`.

3 files changed, 69 insertions, 8 deletions

diff --git a/addons/web/static/src/js/views/kanban/kanban_column.js b/addons/web/static/src/js/views/kanban/kanban_column.js
index 642ab2e8aeb..d999ee74025 100644
--- a/addons/web/static/src/js/views/kanban/kanban_column.js
+++ b/addons/web/static/src/js/views/kanban/kanban_column.js
@@ -44,7 +44,6 @@ var KanbanColumn = Widget.extend({
         this.folded = !data.isOpen;
         this.has_active_field = 'active' in data.fields;
         this.size = data.count;
-        this.values = data.values;
         this.fields = data.fields;
         this.records = [];
         this.modelName = data.model;
@@ -62,13 +61,12 @@ var KanbanColumn = Widget.extend({
 
         this.record_options = _.clone(recordOptions);
 
-        if (data.options && data.options.group_by_tooltip) {
-            var self = this;
-            this.tooltip_info = _.map(data.options.group_by_tooltip, function (key, value) {
-                return (self.values && self.values[value] && "<div>" +key + "<br>" + self.values[value] + "</div>") || '';
+        if (options.group_by_tooltip) {
+            this.tooltipInfo = _.map(options.group_by_tooltip, function (help, field) {
+                return (data.tooltipData && data.tooltipData[field] && "<div>" + help + "<br>" + data.tooltipData[field] + "</div>") || '';
             }).join('');
         } else {
-            this.tooltip_info = "";
+            this.tooltipInfo = "";
         }
     },
     /**
@@ -216,7 +214,7 @@ var KanbanColumn = Widget.extend({
 
         this.$el.toggleClass('o_column_folded', this.folded);
         var tooltip = this.size + _t(' records');
-        tooltip = '<p>' + tooltip + '</p>' + this.tooltip_info;
+        tooltip = '<p>' + tooltip + '</p>' + this.tooltipInfo;
         this.$header.tooltip({html: true}).attr('data-original-title', tooltip);
         if (!this.remaining) {
             this.$('.o_kanban_load_more').remove();
diff --git a/addons/web/static/src/js/views/kanban/kanban_model.js b/addons/web/static/src/js/views/kanban/kanban_model.js
index c606776ccc0..cd69889bda9 100644
--- a/addons/web/static/src/js/views/kanban/kanban_model.js
+++ b/addons/web/static/src/js/views/kanban/kanban_model.js
@@ -90,6 +90,21 @@ var KanbanModel = BasicModel.extend({
             });
     },
     /**
+     * Add the key `tooltipData` (kanban specific) when performing a `geŧ`.
+     *
+     * @override
+     * @see _readTooltipFields
+     * @returns {Object}
+     */
+    get: function () {
+        var result = this._super.apply(this, arguments);
+        var dp = result && this.localData[result.id];
+        if (dp && dp.tooltipData) {
+            result.tooltipData = $.extend(true, {}, dp.tooltipData);
+        }
+        return result;
+    },
+    /**
      * @override
      */
     load: function (params) {
@@ -203,10 +218,55 @@ var KanbanModel = BasicModel.extend({
      * @param {Object} list valid resource object
      */
     _readGroup: function (list) {
+        var self = this;
         if (list.groupedBy.length > 1) {
             list.groupedBy = [list.groupedBy[0]];
         }
-        return this._super.apply(this, arguments);
+        return this._super.apply(this, arguments).then(function (result) {
+            return self._readTooltipFields(list).then(_.constant(result));
+        });
+    },
+    /**
+     * Fetches tooltip specific fields on the group by relation and stores it in
+     * the column datapoint in a special key `tooltipData`.
+     * Data for the tooltips (group_by_tooltip) are fetched in batch for all
+     * groups, to avoid doing multiple calls.
+     * Data are stored in a special key `tooltipData` on the datapoint.
+     * Note that the option `group_by_tooltip` is only for m2o fields.
+     *
+     * @private
+     * @param {Object} list a list of groups
+     * @returns {Deferred}
+     */
+    _readTooltipFields: function (list) {
+        var self = this;
+        var groupedByField = list.fields[list.groupedBy[0]];
+        if (groupedByField.type !== 'many2one') {
+            return $.when();
+        }
+        var groupIds = _.map(list.data, function (id) {
+            return self.get(id, {raw: true}).res_id;
+        });
+        var tooltipFields = [];
+        var groupedByFieldInfo = list.fieldsInfo.kanban[list.groupedBy[0]];
+        if (groupedByFieldInfo && groupedByFieldInfo.options) {
+            tooltipFields = Object.keys(groupedByFieldInfo.options.group_by_tooltip || {});
+        }
+        if (groupIds.length && tooltipFields.length) {
+            var fieldNames = _.union(['display_name'], tooltipFields);
+            return this._rpc({
+                model: groupedByField.relation,
+                method: 'read',
+                args: [groupIds, fieldNames],
+                context: list.context,
+            }).then(function (result) {
+                _.each(list.data, function (id) {
+                    var dp = self.localData[id];
+                    dp.tooltipData = _.findWhere(result, {id: dp.res_id});
+                });
+            });
+        }
+        return $.when();
     },
 });
 
diff --git a/addons/web/static/src/js/views/kanban/kanban_renderer.js b/addons/web/static/src/js/views/kanban/kanban_renderer.js
index 7bfe21e66a9..87275260b01 100644
--- a/addons/web/static/src/js/views/kanban/kanban_renderer.js
+++ b/addons/web/static/src/js/views/kanban/kanban_renderer.js
@@ -188,6 +188,7 @@ var KanbanRenderer = BasicRenderer.extend({
     _renderGrouped: function (fragment) {
         var self = this;
         var groupByFieldAttrs = this.state.fields[this.state.groupedBy[0]];
+        var groupByFieldInfo = this.state.fieldsInfo.kanban[this.state.groupedBy[0]];
         // Deactivate the drag'n'drop if the groupedBy field:
         // - is a date or datetime since we group by month or
         // - is readonly
@@ -201,8 +202,10 @@ var KanbanRenderer = BasicRenderer.extend({
         }
         var groupedByM2O = groupByFieldAttrs && (groupByFieldAttrs.type === 'many2one');
         var grouped_by_field = groupedByM2O && groupByFieldAttrs.relation;
+        var groupByTooltip = groupByFieldInfo && groupByFieldInfo.options.group_by_tooltip;
         this.columnOptions = _.extend(this.columnOptions, {
             draggable: draggable,
+            group_by_tooltip: groupByTooltip,
             grouped_by_m2o: groupedByM2O,
             relation: grouped_by_field,
         });