Initial import from Docker volume

model/union.py

@@ -0,0 +1,68 @@
+# This file is part of Tryton.  The COPYRIGHT file at the toplevel of this
+# repository contains the full copyright notices and license terms.
+from sql import Column, Literal, Union
+
+from trytond.model import fields
+from trytond.pool import Pool
+
+
+class UnionMixin:
+    'Mixin to combine models'
+    __slots__ = ()
+
+    @staticmethod
+    def union_models():
+        return []
+
+    @classmethod
+    def union_shard(cls, column, model):
+        models = cls.union_models()
+        length = len(models)
+        i = models.index(model)
+        return ((column * length) + i)
+
+    @classmethod
+    def union_unshard(cls, record_id):
+        pool = Pool()
+        models = cls.union_models()
+        length = len(models)
+        record_id, i = divmod(record_id, length)
+        Model = pool.get(models[i])
+        return Model(record_id)
+
+    @classmethod
+    def union_column(cls, name, field, table, Model):
+        column = Literal(None)
+        union_field = Model._fields.get(name)
+        if union_field:
+            column = Column(table, union_field.name)
+            if (isinstance(field, fields.Many2One)
+                    and field.model_name == cls.__name__):
+                target_model = union_field.model_name
+                if target_model in cls.union_models():
+                    column = cls.union_shard(column, target_model)
+                else:
+                    column = Literal(None)
+        return column
+
+    @classmethod
+    def union_columns(cls, model):
+        pool = Pool()
+        Model = pool.get(model)
+        table = Model.__table__()
+        columns = [cls.union_shard(table.id, model).as_('id')]
+        for name in sorted(cls._fields.keys()):
+            field = cls._fields[name]
+            if name == 'id' or hasattr(field, 'set'):
+                continue
+            column = cls.union_column(name, field, table, Model)
+            columns.append(field.sql_cast(column).as_(name))
+        return table, columns
+
+    @classmethod
+    def table_query(cls):
+        queries = []
+        for model in cls.union_models():
+            table, columns = cls.union_columns(model)
+            queries.append(table.select(*columns))
+        return Union(*queries)