Merge pull request #65 from Aristotle-Metadata-Enterprises/fixValues

Fixes .values in QuerySet for translatable values

Author: s-i-l-k-e

README.md

@@ -117,7 +117,7 @@ Pros:
 
 Cons:
 * You need to alter the models, so you can't make third-party libraries translatable.
-* It doesn't work on `queryset.values_list` - but we have a workaround below.
+* It doesn't work on `queryset.values_list` or `queryset.values` natively - but we have an easy Queryset Mixin to add language support for both below.
 
 ## Why write a new Django field translator?
 
@@ -283,17 +283,19 @@ with set_field_language("fr"):
 greeting.save()
 ```
 
-## Using Garnett with `values_list`
+## Using Garnett with `values_list` or `values`
 
 This is one of the areas that garnett _doesn't_ work immediately, but there is a solution.
 
-In the places you are using values lists, wrap any translated field in an L-expression and the values list will return correctly. For example:
+In the places you are using values lists or `values`, wrap any translated field in an L-expression and the values list will return correctly. For example:
 
 ```python
 from garnett.expressions import L
 Book.objects.values_list(L("title"))
+Book.objects.values(L("title"))
 ```
 
+
 ## Using Garnett with Django-Rest-Framework
 
 As `TranslationField`s are based on JSONField, by default Django-Rest-Framework renders these as a JSONField, which may not be ideal.

garnett/expressions.py

@@ -6,6 +6,8 @@
 
 
 # Based on: https://code.djangoproject.com/ticket/29769#comment:5
+# Updated comment here
+# https://code.djangoproject.com/ticket/31639
 class LangF(F):
     def resolve_expression(
         self, query=None, allow_joins=True, reuse=None, summarize=False, for_save=False

garnett/mixins.py

@@ -0,0 +1,62 @@
+from django.db.models.query import BaseIterable
+from garnett.expressions import L
+
+PREFIX = "L_garnett__"
+
+
+class TranslatableValuesIterable(BaseIterable):
+    """
+    Unwind the modifications that are made before calling .values()
+    Iterable returned by QuerySet.values() that yields a dict for each row.
+    """
+
+    def clean_garnett_field(self, field_name) -> str:
+        """Return the field name minus the prefix"""
+        return field_name.replace(PREFIX, "")
+
+    def __iter__(self):
+        queryset = self.queryset
+        query = queryset.query
+        compiler = query.get_compiler(queryset.db)
+
+        # extra(select=...) cols are always at the start of the row.
+        names = [
+            *query.extra_select,
+            *query.values_select,
+            *query.annotation_select,
+        ]
+        indexes = range(len(names))
+        for row in compiler.results_iter(
+            chunked_fetch=self.chunked_fetch, chunk_size=self.chunk_size
+        ):
+            yield {self.clean_garnett_field(names[i]): row[i] for i in indexes}
+
+
+class TranslatedQuerySetMixin:
+    """
+    A translated QuerySet mixin to add extra functionality to translated fields
+    Must be mixedin to a QuerySet
+    """
+
+    def values(self, *fields, **expressions):
+        """
+        .values() for translatable fields
+        Still expects values to be passed with L()
+        """
+
+        # Convert anything that is an L from a field to an expression - so it treats it as an expression
+        # rather than a field.
+        # We will clean the field prefix in our custom iterable class "TranslatableQuerySetMixin"
+        cleaned_fields = []
+        for field in fields:
+            if isinstance(field, L):
+                expressions.update(
+                    {f"{PREFIX}{field.source_expressions[0].name}": field}
+                )
+            else:
+                cleaned_fields.append(field)
+
+        clone = super().values(*cleaned_fields, **expressions)
+        clone._iterable_class = TranslatableValuesIterable
+
+        return clone

garnett/patch.py

@@ -25,9 +25,8 @@ class JoinInfo:
     @property
     def transform_function(self):
         if isinstance(self.final_field, TranslatedField):
-            # If its a partial, it must have had a transformer applied - leave it alone!
+            # If it's a partial, it must have had a transformer applied - leave it alone!
             if isinstance(self.transform_function_func, functools.partial):
-
                 return self.transform_function_func
 
             name = get_current_language()

garnett/translatedstr.py

@@ -98,7 +98,7 @@ def get_fallback_text(cls, content):
 
 class NextTranslatedStr(TranslatedStr, HTMLTranslationMixin):
     """
-    A translated string that fallsback based on the order of preferred langages in the app.
+    A translated string that falls back based on the order of preferred languages in the app.
     """
 
     @classmethod

pyproject.toml

@@ -1,6 +1,6 @@
 [tool.poetry]
 name = "django-garnett"
-version = "0.4.4"
+version = "0.4.5"
 description = "Simple translatable Django fields"
 authors = ["Aristotle Metadata Enterprises"]
 license = "BSD-3-Clause"

run.sh

@@ -1,3 +1,5 @@
+#!/bin/bash
+
 export PYTHONPATH=$PYTHONPATH:/app:/app/tests/:/usr/src/app:/usr/src/app/tests/
 export DJANGO_SETTINGS_MODULE=library_app.settings
 

tests/library_app/managers.py

@@ -0,0 +1,6 @@
+from django.db.models import QuerySet
+from garnett.mixins import TranslatedQuerySetMixin
+
+
+class BookQuerySet(TranslatedQuerySetMixin, QuerySet):
+    pass

tests/library_app/models.py

@@ -50,20 +50,24 @@ def __html__(self) -> str:
 
 class Book(models.Model):
     number_of_pages = models.PositiveIntegerField()
+
     title = fields.Translated(
         models.CharField(max_length=250, validators=[validate_length]),
         fallback=TitleTranslatedStr,
         help_text=_("The name for a book. (Multilingal field)"),
     )
+
     author = models.TextField(
         help_text=_(
             "The name of the person who wrote the book (Single language field)"
         ),
         default="Anon",
     )
+
     description = fields.Translated(
         models.TextField(help_text=_("Short details about a book. (Multilingal field)"))
     )
+
     category = models.JSONField(blank=True, null=True)
 
     def get_absolute_url(self):