add expression builder to mail template substitutions

models/redner_substitution.py

@@ -119,3 +119,40 @@
             d[sub.keyword.rsplit(".", 2)[-1]] = conv
 
         return converter.Model("", d)
+
+    def action_build_expression(self):
+        if not (self and self.ir_actions_report_id):
+            if not self.template_id:
+                # neither a report nor a mail template
+                return
+            else:
+                model = self.env.get(self.template_id.model_id.model)
+        else:
+            model = self.env.get(self.ir_actions_report_id.model)
+        if model is None:
+            return
+
+        # reset the older substitution value
+        self.value = ""
+
+        wizard = self.env["expression.builder.wizard"].create(
+            {
+                "substitution_id": self.id,
+                "expression": "",
+            }
+        )
+
+        vals_list = wizard.get_fields(model, self.converter)
+        for val in vals_list:
+            val["wizard_id"] = wizard.id
+
+        fields_list = self.env["expression.builder.field"].create(vals_list)
+        wizard.suggested_fields = [(6, 0, fields_list.ids)]
+
+        return {
+            "type": "ir.actions.act_window",
+            "res_model": "expression.builder.wizard",
+            "view_mode": "form",
+            "res_id": wizard.id,
+            "target": "new",
+        }

views/mail_template.xml

@@ -40,6 +40,28 @@
                             <field name="keyword" />
                             <field name="converter" />
                             <field name="value" />
+                            <button
+                                name="action_build_expression"
+                                type="object"
+                                string="Build expression"
+                                class="oe_highlight"
+                                invisible="not (value and value!='') or not (converter and converter in ['field','relation-to-many'])"
+                                confirm="This will delete the current substitution value. Continue anyway ?"
+                            />
+                            <button
+                                name="action_build_expression"
+                                type="object"
+                                string="Build expression"
+                                class="oe_highlight"
+                                invisible="(value and value !='') or not (converter and converter in ['field','relation-to-many'])"
+                            />
+                            <button
+                                name="action_build_expression"
+                                type="object"
+                                string="Build expression"
+                                class="oe_highlight disabled"
+                                invisible="converter in ['field','relation-to-many']"
+                            />
                         </list>
                     </field>
                 </group>