[FIX] ir_model_fields: properly unlink manual fields

Before this commit:

* Install module A that implements model M and field X.

* Create a new custom field Y whose reference model is not M, implemented in
any module other than A.

* Make this field either a one2many, related or compute field depending
on field X.

* Uninstall module A.

=> The registry crashes fatally, the only way to recover from this is to
log directly into the postgres database and manually eliminate the
infringing ir.model.fields record.

The reasons are multiple:

* When creating custom fields that are relational, char fields are used
to hold data like model name, field name, instead of properly storing
the related field, which would let postgres handle the unlinking
properly.

* Despite this, the ir.model.fields method _prepare_update tries to make
up for this by verifying that the ir.model.fields being unlinked during
an uninstallation are not needed elsewhere and drops them, however it
does so naively: It assumes that the "problematic" field will be defined
within the module's scope, i.e. its model reference will be a model
defined by the module being uninstalled, this isn't always the case.

This is solved by getting the dependants of each field by accessing the
model's field_triggers, if there are any triggers (i.e. dependants) then
we add them to a `failed_dependencies` list for later processing. The same
is done for field inverses (only in the case of a many2one).

After finding the failed_dependencies, a check is performed to see if the unlink is
being performed in the context of an uninstallation, in which case the failed
dependencies will be unlinked, otherwise an error will be shown to the user.

This commit is a "backport" + generalization of commit 4265026ee23ab71e8b199a9d8cbbd439409d7a03

Task-ID: 1856263

0 files changed, 0 insertions, 0 deletions