Fix bug that made previous images to disappear.

See https://github.com/OCA/product-attribute/pull/135#issuecomment-191358505.

base_multi_image/README.rst

@@ -55,6 +55,20 @@ To develop a module based on this one:
         }"
         mode="kanban"/>
 
+* If the model you are extending already had an image field, and you want to
+  trick Odoo to make those images to multi-image mode, you will need to make
+  use of the provided :meth:`~.hooks.pre_init_hook_for_submodules`, like
+  the ``product_multi_image`` module does::
+
+    from openerp.addons.base_multi_image.hooks import \
+        pre_init_hook_for_submodules
+
+
+    def pre_init_hook(cr):
+        pre_init_hook_for_submodules(cr, "product.template", "image")
+        pre_init_hook_for_submodules(cr, "product.product", "image_variant")
+
+
 .. image:: https://odoo-community.org/website/image/ir.attachment/5784_f2813bd/datas
    :alt: Try me on Runbot
    :target: https://runbot.odoo-community.org/runbot/149/8.0

base_multi_image/__openerp__.py

@@ -7,7 +7,7 @@
 {
     "name": "Multiple images base",
     "summary": "Allow multiple images for database objects",
-    "version": "8.0.1.0.0",
+    "version": "8.0.2.0.0",
     "author": "Serv. Tecnol. Avanzados - Pedro M. Baeza, "
               "Antiun Ingeniería, S.L., "
               "Odoo Community Association (OCA)",

base_multi_image/hooks.py

@@ -2,16 +2,16 @@
 # © 2016 Antiun Ingeniería S.L. - Jairo Llopis
 # License AGPL-3.0 or later (http://www.gnu.org/licenses/agpl.html).
 
-from openerp import SUPERUSER_ID
+from openerp import api, SUPERUSER_ID
 import logging
 
 _logger = logging.getLogger(__name__)
 
 
-def post_init_hook_for_submodules(cr, registry, model, field):
+def pre_init_hook_for_submodules(cr, model, field):
     """Moves images from single to multi mode.
 
-    Feel free to use this as a ``post_init_hook`` for submodules.
+    Feel free to use this as a ``pre_init_hook`` for submodules.
 
     :param str model:
         Model name, like ``product.template``.
@@ -20,14 +20,25 @@ def post_init_hook_for_submodules(cr, registry, model, field):
         Binary field that had the images in that :param:`model`, like
         ``image``.
     """
+    env = api.Environment(cr, SUPERUSER_ID, dict())
     with cr.savepoint():
-        records = registry[model].search(
-            cr,
-            SUPERUSER_ID,
-            [(field, "!=", False)],
-            context=dict())
-
-        _logger.info("Moving images from %s to multi image mode.", model)
-        for r in registry[model].browse(cr, SUPERUSER_ID, records):
-            _logger.debug("Setting up multi image for record %d.", r.id)
-            r.image_main = r[field]
+        cr.execute(
+            """
+                INSERT INTO base_multi_image_image (
+                    owner_id,
+                    owner_model,
+                    storage,
+                    file_db_store
+                )
+                SELECT
+                    id,
+                    %%s,
+                    'db',
+                    %(field)s
+                FROM
+                    %(table)s
+                WHERE
+                    %(field)s IS NOT NULL
+            """ % {"table": env[model]._table, "field": field},
+            (model,)
+        )