[REF] move support for sparse fields into a separate module (#15070)

This removal has led to a necessary refactoring:
- make the setup of field attributes extensible;
- make the instantiation of custom fields extensible;
- delegate model and field reflection to `ir.model` and `ir.model.fields`;
- move the implementation of sparse and serialized fields to module `base_sparse_field`;

1 files changed, 18 insertions, 0 deletions

diff --git a/addons/base_sparse_field/__manifest__.py b/addons/base_sparse_field/__manifest__.py
new file mode 100644
index 00000000000..031a6c179de
--- /dev/null
+++ b/addons/base_sparse_field/__manifest__.py
@@ -0,0 +1,18 @@
+# -*- coding: utf-8 -*-
+{
+    'name': "Sparse Fields",
+    'summary': """Implementation of sparse fields.""",
+    'description': """
+        The purpose of this module is to implement "sparse" fields, i.e., fields
+        that are mostly null. This implementation circumvents the PostgreSQL
+        limitation on the number of columns in a table. The values of all sparse
+        fields are stored in a "serialized" field in the form of a JSON mapping.
+    """,
+    'category': 'Technical Settings',
+    'version': '1.0',
+    'depends': ['base'],
+    'data': [
+        'views/views.xml',
+    ],
+    'pre_init_hook': '_update_database_schema',
+}