Fixed #25841 -- Handled base array fields validation errors with params.

Thanks to Trac alias benzid-wael for the report.

1 files changed, 30 insertions, 0 deletions

diff --git a/django/contrib/postgres/utils.py b/django/contrib/postgres/utils.py
new file mode 100644
index 0000000000..1563149c7e
--- /dev/null
+++ b/django/contrib/postgres/utils.py
@@ -0,0 +1,30 @@
+from __future__ import unicode_literals
+
+from django.core.exceptions import ValidationError
+from django.utils.functional import SimpleLazyObject
+from django.utils.translation import string_concat
+
+
+def prefix_validation_error(error, prefix, code, params):
+    """
+    Prefix a validation error message while maintaining the existing
+    validation data structure.
+    """
+    if error.error_list == [error]:
+        error_params = error.params or {}
+        return ValidationError(
+            # We can't simply concatenate messages since they might require
+            # their associated parameters to be expressed correctly which
+            # is not something `string_concat` does. For example, proxied
+            # ungettext calls require a count parameter and are converted
+            # to an empty string if they are missing it.
+            message=string_concat(
+                SimpleLazyObject(lambda: prefix % params),
+                SimpleLazyObject(lambda: error.message % error_params),
+            ),
+            code=code,
+            params=dict(error_params, **params),
+        )
+    return ValidationError([
+        prefix_validation_error(e, prefix, code, params) for e in error.error_list
+    ])