Create a message corresponding to localization with python translation string

You may want to sort out error messages depending on the locale. I didn't know what to do in such a case, so I looked it up.

translationstring

Use translationstring. This seems to be used for localization in the package related to the pylons project. It seems that it uses the gettext mechanism that is often used for general translation.

python side code

"Failure" in Japanese locale. Otherwise, consider a string that displays "failure".

It seems that the function generated by translationstring.TranslationStringFactory should be used for the notation. Wrap it in a Translator Object to convert the value.

In addition to the code below, you need a .mo file in place.

translationstring_example.py

# -*- coding:utf-8 -*-
import gettext
import translationstring

# .To work well with the po file generation tool_It is better to name it
_ = translationstring.TranslationStringFactory('sample')

lang = gettext.translation("sample", "./locale", languages=["ja"], codeset="utf8")
translator = translationstring.Translator(lang)

print(translator(_("failure")))

Generate .mo file

The .mo file is the format used by gettext. Generated from a .po file using commands using msgfmt. Generate a .po file before the .mo file. Use pot-create for this.

lingua install

A package called lingua will generate a .po file for you. ligua itself doesn't need babel, but babel was requested when trying to run pot-create.

pip install lingua babel

Generate .po file

After installing lingua, you can use pot-create. Generate a .po file in place

mkdir -p locale/ja/LC_MESSAGES/
pot-create translation_example.py -o locale/ja/LC_MESSAGES/sample.po

The file name to rewrite the generated sample.po should be the same as the domain name passed to TranslationStringFactory.

Rewrite as follows. Originally, it is better to rewrite the part such as the translator's name. This time I just rewrote the last part

# 
# SOME DESCRIPTIVE TITLE
# This file is distributed under the same license as the PACKAGE package.
# FIRST AUTHOR <EMAIL@ADDRESS>, 2014.
#, fuzzy
msgid ""
msgstr ""
"Project-Id-Version: PACKAGE 1.0\n"
"POT-Creation-Date: 2014-06-12 15:37+09:00\n"
"PO-Revision-Date: YEAR-MO-DA HO:MI+ZONE\n"
"Last-Translator: FULL NAME <EMAIL@ADDRESS\n"
"Language-Team: LANGUAGE <[email protected]>\n"
"MIME-Version: 1.0\n"
"Content-Type: text/plain; charset=UTF-8\n"
"Content-Transfer-Encoding: 8bit\n"
"Language: \n"

#: ./translation_example.py:11
#, c-format
msgid "failure"
msgstr "Failure value"

The difference is as follows

diff --git a/locale/ja/LC_MESSAGES/sample.po b/locale/ja/LC_MESSAGES/sample.po
index 2559ffb..db040c4 100644
--- a/locale/ja/LC_MESSAGES/sample.po
+++ b/locale/ja/LC_MESSAGES/sample.po
@@ -18,4 +18,4 @@ msgstr ""
 #: ./translation_example.py:11
 #, c-format
 msgid "failure"
-msgstr ""
+msgstr "Failure value"

Creating a .mo file

Use msgfmt to create .mo files.

msgfmt locale/ja/LC_MESSAGES/sample.po -o locale/ja/LC_MESSAGES/sample.mo

$ tree
.
├── locale
│   └── ja
│       └── LC_MESSAGES
│           ├── sample.mo
│           └── sample.po
├── requirements.txt
└── translation_example.py

3 directories, 4 files

This will translate "failure" into "failure value" and display it.

$ python translation_example.py
Failure value

About the location of ja / LC_MESSAGES / sample.mo

gettext looks at the locales information and asks for the mapping to use when translating.

LANG="ja_JP.UTF-8"
LC_COLLATE="ja_JP.UTF-8"
LC_CTYPE="ja_JP.UTF-8"
LC_MESSAGES="ja_JP.UTF-8"
LC_MONETARY="ja_JP.UTF-8"
LC_NUMERIC="ja_JP.UTF-8"
LC_TIME="ja_JP.UTF-8"
LC_ALL=

It seems good to use gettext.find to check if the .mo file can be read successfully.

# -*- coding:utf-8 -*-
import gettext
print(gettext.find("sample", "./locale",["ja"]))
# ./locale/ja/LC_MESSAGES/sample.mo

You can find out where to create the .po file by looking at the gettext.find code.

gettext.py

# Locate a .mo file using the gettext strategy
def find(domain, localedir=None, languages=None, all=False):
    # Get some reasonable defaults for arguments that were not supplied
    if localedir is None:
        localedir = _default_localedir
    if languages is None:
        languages = []
        for envar in ('LANGUAGE', 'LC_ALL', 'LC_MESSAGES', 'LANG'):
            val = os.environ.get(envar)
            if val:
                languages = val.split(':')
                break
        if 'C' not in languages:
            languages.append('C')
    # now normalize and expand the languages
    nelangs = []
    for lang in languages:
        for nelang in _expand_lang(lang):
            if nelang not in nelangs:
                nelangs.append(nelang)
    # select a language
    if all:
        result = []
    else:
        result = None
    for lang in nelangs:
        if lang == 'C':
            break
        mofile = os.path.join(localedir, lang, 'LC_MESSAGES', '%s.mo' % domain)
        if os.path.exists(mofile):
            if all:
                result.append(mofile)
            else:
                return mofile
    return result

Roughly, get languages such as "ja" from ('LANGUAGE','LC_ALL','LC_MESSAGES','LANG'), You can see that it is trying to retrieve the value from the .mo file under localedir / ja / LC_MESSAGS /.

About translating strings that take arguments

translationstring can also translate sentences that take arguments.

msg2 = _("add-number", default="Add ${number}", mapping={"number": 1})

lang = gettext.translation("sample", "./locale", languages=["ja"], codeset="utf8")
translator = translationstring.Translator()

print(translator(_("add-number", mapping={"number": 10})))
#Add 10

At this time, write the .placeholder in $ {} in the .po file as shown below.

msgid "add-number"
msgstr "${number}Please add"