Added the get_multi_language_attr() function to the Mia core application, to deal with the multi-lingual attributes, and applied it in the data models.

accounting/models.py

@@ -22,6 +22,8 @@ from django.conf import settings
 from django.db import models
 from django.urls import reverse
 
+from mia_core.utils import get_multi_language_attr
+
 
 class Subject(models.Model):
     """An accounting subject."""
@@ -50,7 +52,19 @@ class Subject(models.Model):
     def __str__(self):
         """Returns the string representation of this accounting
         subject."""
-        return self.code.__str__() + " " + self.title_zhtw.__str__()
+        return self.code.__str__() + " " + self.title
+
+    _title = None
+
+    @property
+    def title(self):
+        if self._title is None:
+            self._title = get_multi_language_attr(self, "title")
+        return self._title
+
+    @title.setter
+    def title(self, value):
+        self._title = value
 
     class Meta:
         db_table = "accounting_subjects"
@@ -241,7 +255,7 @@ class Record(models.Model):
         record."""
         return "%s %s %s %s" % (
             self.transaction.date,
-            self.subject.title_zhtw,
+            self.subject.title,
             self.summary,
             self.amount)
 

accounting/templates/accounting/cash.html

@@ -25,7 +25,7 @@ First written: 2020/7/1
 {% load accounting %}
 
 {% block settings %}
-  {% blocktrans asvar title with subject=current_subject.title_zhtw period=period.description context "Accounting|" %}Cash Account for {{ subject }} in {{ period }}{% endblocktrans %}
+  {% blocktrans asvar title with subject=current_subject.title|title period=period.description context "Accounting|" %}Cash Account for {{ subject }} in {{ period }}{% endblocktrans %}
   {% setvar "title" title %}
   {% setvar "use_period_chooser" True %}
 {% endblock %}
@@ -63,17 +63,17 @@ First written: 2020/7/1
   {% endwith %}
   <div class="btn-group">
     <button type="button" class="btn btn-primary dropdown-toggle" data-toggle="dropdown">
-      <span class="d-none d-md-inline">{{ current_subject.title_zhtw }}</span>
+      <span class="d-none d-md-inline">{{ current_subject.title|title }}</span>
       <span class="d-md-none">{% trans "Subject" context "Accounting|" as text %}{{ text|force_escape }}</span>
     </button>
     <div class="dropdown-menu subject-picker">
       <div class="dropdown-header">{% trans "Shortcuts" context "Accounting|Subject|" as text %}{{ text|force_escape }}</div>
       {% for subject in shortcut_subjects %}
-        <a class="dropdown-item {% if subject.code == current_subject.code %}{% endif %}>" href="{% url "accounting:cash" subject.code period.spec %}">{{ subject.title_zhtw|title }}</a>
+        <a class="dropdown-item {% if subject.code == current_subject.code %}{% endif %}>" href="{% url "accounting:cash" subject.code period.spec %}">{{ subject.title|title }}</a>
       {% endfor %}
       <div class="dropdown-header">{% trans "All" context "Accounting|Subject|" as text %}{{ text|force_escape }}</div>
       {% for subject in all_sibjects %}
-        <a class="dropdown-item {% if subject.code == current_subject.code %}{% endif %}>" href="{% url "accounting:cash" subject.code period.spec %}">{{ subject.title_zhtw|title }}</a>
+        <a class="dropdown-item {% if subject.code == current_subject.code %}{% endif %}>" href="{% url "accounting:cash" subject.code period.spec %}">{{ subject.title|title }}</a>
       {% endfor %}
     </div>
   </div>
@@ -106,7 +106,7 @@ First written: 2020/7/1
       {% for record in records %}
         <tr class="{% if not record.transaction.is_balanced or record.transaction.has_order_hole %} table-danger {% endif %}">
           <td>{{ record.transaction.date|smart_date }}</td>
-          <td>{{ record.subject.title_zhtw }}</td>
+          <td>{{ record.subject.title|title }}</td>
           <td>{{ record.summary|default:"" }}{% if not record.transaction.is_balanced %}
             <span class="badge badge-danger badge-pill">
               {% trans "Unbalanced" context "Accounting|" as text %}
@@ -141,7 +141,7 @@ First written: 2020/7/1
         {% if record.sn is not None %}
           <a class="list-group-item-action" href="{{ record.transaction.get_absolute_url }}">
             <div class="date-subject-line d-flex justify-content-between align-items-center">
-              {{ record.transaction.date|smart_date }} {{ record.subject.title_zhtw }}
+              {{ record.transaction.date|smart_date }} {{ record.subject.title|title }}
             </div>
             <div class="d-flex justify-content-between align-items-center">
               <div>
@@ -168,7 +168,7 @@ First written: 2020/7/1
           </a>
         {% else %}
           <div class="date-subject-line d-flex justify-content-between align-items-center">
-            {{ record.transaction.date|smart_date }} {{ record.subject.title_zhtw }}
+            {{ record.transaction.date|smart_date }} {{ record.subject.title }}
           </div>
           <div class="d-flex justify-content-between align-items-center">
             <div>{{ record.summary|default:"" }}</div>

accounting/views/__init__.py

@@ -88,7 +88,7 @@ FROM accounting_subjects AS s
   ORDER BY s.code"""))
     subjects.insert(0, Subject(
         code="0",
-        title_zhtw=pgettext(
+        title=pgettext(
             "Accounting|", "current assets and liabilities"),
     ))
     current_subject = None

mia_core/models.py

@@ -21,6 +21,8 @@
 
 from django.db import models
 
+from mia_core.utils import get_multi_language_attr
+
 
 class Country(models.Model):
     """A country."""
@@ -46,6 +48,18 @@ class Country(models.Model):
         """Returns the string representation of this country."""
         return self.code.__str__() + " " + self.name_zhtw.__str__()
 
+    _title = None
+
+    @property
+    def title(self):
+        if self._title is None:
+            self._title = get_multi_language_attr(self, "title")
+        return self._title
+
+    @title.setter
+    def title(self, value):
+        self._title = value
+
     class Meta:
         db_table = "countries"
         ordering = ["code"]

mia_core/utils.py

@@ -21,7 +21,60 @@
 
 import urllib.parse
 
-from django.utils.translation import pgettext
+from django.conf import settings
+from django.utils.translation import pgettext, get_language
+
+
+class Language:
+    """A language.
+
+    Args:
+        language (str): The Django language code.
+
+    Attributes:
+        db (str): The database column suffix of this language.
+        locale (str); The locale name of this language.
+        is_default (bool): Whether this is the default language.
+    """
+    db = None
+    locale = None
+    is_default = False
+
+    def __init__(self, language):
+        if language == "zh-hant":
+            self.locale = "zh-TW"
+            self.db = "zhtw"
+        elif language == "zh-hans":
+            self.locale = "zh-CN"
+            self.db = "zhcn"
+        else:
+            self.locale = language
+            self.db = language
+        self.is_default = (language == settings.LANGUAGE_CODE)
+
+    @staticmethod
+    def get_default():
+        return Language(settings.LANGUAGE_CODE)
+
+
+def get_multi_language_attr(model, name):
+    """Returns a multi-language attribute of a data model.
+    
+    Args:
+        model (object): The data model.
+        name (str): The attribute name.
+
+    Returns:
+        (any): The attribute in this language, or in the default
+            language if there is no content in the current language.
+    """
+    language = Language(get_language())
+    title = getattr(model, name + "_" + language.db)
+    if language.is_default:
+        return title
+    if title is not None:
+        return title
+    return getattr(model, name + "_" + Language.get_default().db)
 
 
 class UrlBuilder: