pgAdmin supports multiple languages using the Flask-Babel Python module. A list of supported languages is included in the web/config.py configuration file and must be updated whenever langauges are added or removed.

Translation Marking

Strings can be marked for translation in either Python code (using gettext() ) or Jinja templates (using _() ). Here are some examples that show how this is achieved.

Python: 

errormsg = gettext('No server group name was specified')

Jinja: 

<input type="submit" value="{{ _('Change Password') }}">

<title>{{ _('%(appname)s Password Change', appname=config.APP_NAME) }}title>

var alert = alertify.prompt(
    '{{ _('Add a server group') }}',
    '{{ _('Enter a name for the new server group') }}',
    ''
    ...
)

Updating and Merging

Whenever new strings are added to the application, the template catalogues ( web/pgadmin/messages.pot ) must be updated and the existing catalogues merged with the updated template and compiled. This can be achieved using the following command from the web directory, in the Python virtual environment used for pgAdmin: 

(pgadmin4)piranha:web dpage$ pybabel extract -F babel.cfg -o pgadmin/messages.pot pgadmin

For example: 

(pgadmin4)piranha:web dpage$ pybabel extract -F babel.cfg -o pgadmin/messages.pot pgadmin
extracting messages from pgadmin/__init__.py
extracting messages from pgadmin/about/__init__.py
extracting messages from pgadmin/about/hooks.py
extracting messages from pgadmin/about/views.py
extracting messages from pgadmin/about/templates/about/index.html (extensions="jinja2.ext.autoescape,jinja2.ext.with_")
extracting messages from pgadmin/browser/__init__.py
extracting messages from pgadmin/browser/hooks.py
extracting messages from pgadmin/browser/views.py
extracting messages from pgadmin/browser/nodes/CollectionNode.py
extracting messages from pgadmin/browser/nodes/ObjectNode.py
extracting messages from pgadmin/browser/nodes/__init__.py
extracting messages from pgadmin/browser/nodes/server_groups/__init__.py
extracting messages from pgadmin/browser/nodes/server_groups/hooks.py
extracting messages from pgadmin/browser/nodes/server_groups/views.py
extracting messages from pgadmin/browser/templates/browser/body.html (extensions="jinja2.ext.autoescape,jinja2.ext.with_")
extracting messages from pgadmin/browser/templates/browser/index.html (extensions="jinja2.ext.autoescape,jinja2.ext.with_")
extracting messages from pgadmin/browser/templates/browser/messages.html (extensions="jinja2.ext.autoescape,jinja2.ext.with_")
extracting messages from pgadmin/help/__init__.py
extracting messages from pgadmin/help/hooks.py
extracting messages from pgadmin/help/views.py
extracting messages from pgadmin/redirects/__init__.py
extracting messages from pgadmin/redirects/views.py
extracting messages from pgadmin/settings/__init__.py
extracting messages from pgadmin/settings/hooks.py
extracting messages from pgadmin/settings/settings_model.py
extracting messages from pgadmin/settings/views.py
extracting messages from pgadmin/templates/base.html (extensions="jinja2.ext.autoescape,jinja2.ext.with_")
extracting messages from pgadmin/templates/security/change_password.html (extensions="jinja2.ext.autoescape,jinja2.ext.with_")
extracting messages from pgadmin/templates/security/fields.html (extensions="jinja2.ext.autoescape,jinja2.ext.with_")
extracting messages from pgadmin/templates/security/forgot_password.html (extensions="jinja2.ext.autoescape,jinja2.ext.with_")
extracting messages from pgadmin/templates/security/login_user.html (extensions="jinja2.ext.autoescape,jinja2.ext.with_")
extracting messages from pgadmin/templates/security/messages.html (extensions="jinja2.ext.autoescape,jinja2.ext.with_")
extracting messages from pgadmin/templates/security/panel.html (extensions="jinja2.ext.autoescape,jinja2.ext.with_")
extracting messages from pgadmin/templates/security/reset_password.html (extensions="jinja2.ext.autoescape,jinja2.ext.with_")
extracting messages from pgadmin/templates/security/watermark.html (extensions="jinja2.ext.autoescape,jinja2.ext.with_")
extracting messages from pgadmin/test/__init__.py
extracting messages from pgadmin/test/hooks.py
extracting messages from pgadmin/test/views.py
extracting messages from pgadmin/utils/__init__.py
extracting messages from pgadmin/utils/views.py
writing PO template file to pgadmin/messages.pot

Once the template has been updated, it needs to be merged into the existing message catalogues, for example: 

(pgadmin4)piranha:web dpage$ pybabel update -i pgadmin/messages.pot -d pgadmin/translations
updating catalog 'pgadmin/translations/fr/LC_MESSAGES/messages.po' based on 'pgadmin/messages.pot'

Finally, the message catalogues can be compiled for use: 

(pgadmin4)piranha:web dpage$ pybabel compile -d pgadmin/translations
compiling catalog 'pgadmin/translations/fr/LC_MESSAGES/messages.po' to 'pgadmin/translations/fr/LC_MESSAGES/messages.mo'

Adding a new Language

Adding a new language is simple. First, add the language name and identifier to web/config.py : 

# Languages we support in the UI
LANGUAGES = {
    'en': 'English',
    'fr': 'Français'
}

Then, create the new message catalogue from the web directory in the source tree, in the Python virtual environment used for pgAdmin: 

(pgadmin4)piranha:web dpage$ pybabel init -i pgadmin/messages.pot -d pgadmin/translations -l fr

This will initialise a new catalogue for a French translation.