2018-02-27T18:13:23Z

The Flask Mega-Tutorial Part XIII: I18n and L10n

This is the thirteenth installment of the Flask Mega-Tutorial series, in which I'm going to tell you how to expand Microblog to support multiple languages. As part of that effort you will also learn about creating your own CLI extensions to the flask command.

For your reference, below is a list of the articles in this series.

The topics of this chapter are Internationalization and Localization, commonly abbreviated I18n and L10n. To make my application friendly to people who do not speak English, I'm going to implement a translation workflow that, with the help of language translators, will allow me to offer the application to users in a choice of languages.

The GitHub links for this chapter are: Browse, Zip, Diff.

Introduction to Flask-Babel

As you can probably guess, there is a Flask extension that makes working with translations very easy. The extension is called Flask-Babel and is installed with pip:

(venv) $ pip install flask-babel

Flask-Babel is initialized like most other Flask extensions:

app/__init__.py: Flask-Babel instance.

# ...
from flask_babel import Babel

app = Flask(__name__)
# ...
babel = Babel(app)

As part of this chapter, I'm going to show you how to translate the application into Spanish, as I happen to speak that language. I could also work with translators that know other languages and support those as well. To keep track of the list of supported languages, I'm going to add a configuration variable:

config.py: Supported languages list.

class Config(object):
    # ...
    LANGUAGES = ['en', 'es']

I'm using two-letter language codes for this application, but if you need to be more specific, a country code can be added as well. For example, you could use en-US, en-GB and en-CA to support American, British and Canadian English as different languages.

The Babel instance provides a localeselector decorator. The decorated function is invoked for each request to select a language translation to use for that request:

app/__init__.py: Select best language.

from flask import request

# ...

@babel.localeselector
def get_locale():
    return request.accept_languages.best_match(app.config['LANGUAGES'])

Here I'm using an attribute of Flask's request object called accept_languages. This object provides a high-level interface to work with the Accept-Language header that clients send with a request. This header specifies the client language and locale preferences as a weighted list. The contents of this header can be configured in the browser's preferences page, with the default being usually imported from the language settings in the computer's operating system. Most people don't even know such a setting exists, but this is useful as users can provide a list of preferred languages, each with a weight. In case you are curious, here is an example of a complex Accept-Languages header:

Accept-Language: da, en-gb;q=0.8, en;q=0.7

This says that Danish (da) is the preferred language (with default weight = 1.0), followed by British English (en-GB) with a 0.8 weight, and as a last option generic English (en) with a 0.7 weight.

To select the best language, you need to compare the list of languages requested by the client against the languages the application supports, and using the client provided weights, find the best language. The logic to do this is somewhat complicated, but it is all encapsulated in the best_match() method, which takes the list of languages offered by the application as an argument and returns the best choice.

Marking Texts to Translate In Python Source Code

Okay, so now comes the bad news. The normal workflow when making an application available in multiple languages is to mark all the texts that need translations in the source code. After the texts are marked, Flask-Babel will scan all the files and extract those texts into a separate translation file using the gettext tool. Unfortunately this is a tedious task that needs to be done to enable translations.

I'm going to show you a few examples of this marking here, but you can get the complete set of changes from the download package for this chapter or the GitHub repository.

The way texts are marked for translation is by wrapping them in a function call that as a convention is called _(), just an underscore. The simplest cases are those where literal strings appear in the source code. Here is an example flash() statement:

from flask_babel import _
# ...
flash(_('Your post is now live!'))

The idea is that the _() function wraps the text in the base language (English in this case). This function will use the language selected by the get_locale() function to find the correct translation for a given client. The _() function then returns the translated text, which in this case will become the argument to flash().

Unfortunately not all cases are that simple. Consider this other flash() call from the application:

flash('User {} not found.'.format(username))

This text has a dynamic component that is inserted in the middle of the static text. The _() function has a syntax that supports this type of texts, but it is based on the older string substitution syntax:

flash(_('User %(username)s not found.', username=username))

There is an even harder case to handle. Some string literals are assigned outside of a request, usually when the application is starting up, so at the time these texts are evaluated there is no way to know what language to use. An example of this is the labels associated with form fields. The only solution to handle those texts is to find a way to delay the evaluation of the string until it is used, which is going to be under an actual request. Flask-Babel provides a lazy evaluation version of _() that is called lazy_gettext():

from flask_babel import lazy_gettext as _l

class LoginForm(FlaskForm):
    username = StringField(_l('Username'), validators=[DataRequired()])
    # ...

Here I'm importing this alternative translation function and renaming to to _l() so that it looks similar to the original _(). This new function wraps the text in a special object that triggers the translation to be performed later, when the string is used.

The Flask-Login extension flashes a message any time it redirects the user to the login page. This message is in English and comes from the extension itself. To make sure this message also gets translated, I'm going to override the default message and provide my own, wrapper with the _l() function for lazy processing:

login = LoginManager(app)
login.login_view = 'login'
login.login_message = _l('Please log in to access this page.')

Marking Texts to Translate In Templates

In the previous section you've seen how to mark translatable texts in Python source code, but that is only a part of this process, as template files also have text. The _() function is also available in templates, so the process is fairly similar. For example, consider this snippet of HTML from 404.html:

<h1>File Not Found</h1>

The translation enabled version becomes:

<h1>{{ _('File Not Found') }}</h1>

Note that here in addition to wrapping the text with _(), the {{ ... }} needs to be added, to force the _() to be evaluated instead of being considered a literal in the template.

For more complex phrases that have dynamic components, arguments can also be used:

<h1>{{ _('Hi, %(username)s!', username=current_user.username) }}</h1>

There is a particularly tricky case in _post.html that took me a while to figure out:

        {% set user_link %}
            <a href="{{ url_for('user', username=post.author.username) }}">
                {{ post.author.username }}
            </a>
        {% endset %}
        {{ _('%(username)s said %(when)s',
            username=user_link, when=moment(post.timestamp).fromNow()) }}

The problem here is that I wanted the username to be a link that points to the profile page of the user, not just the name, so I had to create an intermediate variable called user_link using the set and endset template directives, and then pass that as an argument to the translation function.

As I mentioned above, you can download a version of the application with all the translatable texts in Python source code and templates marked.

Extracting Text to Translate

Once you have the application with all the _() and _l() in place, you can use the pybabel command to extract them to a .pot file, which stands for portable object template. This is a text file that includes all the texts that were marked as needing translation. The purpose of this file is to serve as a template to create translation files for each language.

The extraction process needs a small configuration file that tells pybabel what files should be scanned for translatable texts. Below you can see the babel.cfg that I created for this application:

babel.cfg: PyBabel configuration file.

[python: app/**.py]
[jinja2: app/templates/**.html]
extensions=jinja2.ext.autoescape,jinja2.ext.with_

The first two lines define the filename patterns for Python and Jinja2 template files respectively. The third line defines two extensions provided by the Jinja2 template engine that help Flask-Babel properly parse template files.

To extract all the texts to the .pot file, you can use the following command:

(venv) $ pybabel extract -F babel.cfg -k _l -o messages.pot .

The pybabel extract command reads the configuration file given in the -F option, then scans all the code and template files in the directories that match the configured sources, starting from the directory given in the command (the current directory or . in this case). By default, pybabel will look for _() as a text marker, but I have also used the lazy version, which I imported as _l(), so I need to tell the tool to look for those too with the -k _l. The -o option provides the name of the output file.

I should note that the messages.pot file is not a file that needs to be incorporated into the project. This is a file that can be easily regenerated any time it is needed, simply by running the command above again. So there is no need to commit this file to source control.

Generating a Language Catalog

The next step in the process is to create a translation for each language that will be supported in addition to the base one, which in this case is English. I said I was going to start by adding Spanish (language code es), so this is the command that does that:

(venv) $ pybabel init -i messages.pot -d app/translations -l es
creating catalog app/translations/es/LC_MESSAGES/messages.po based on messages.pot

The pybabel init command takes the messages.pot file as input and writes a new language catalog to the directory given in the -d option for the language specified in the -l option. I'm going to be installing all the translations in the app/translations directory, because that is where Flask-Babel will expect translation files to be by default. The command will create a es subdirectory inside this directory for the Spanish data files. In particular, there will be a new file named app/translations/es/LC_MESSAGES/messages.po, that is where the translations need to be made.

If you want to support other languages, just repeat the above command with each of the language codes you want, so that each language gets its own repository with a messages.po file.

This messages.po file that created in each language repository uses a format that is the de facto standard for language translations, the format used by the gettext utility. Here are a few lines from the beginning of the Spanish messages.po:

# Spanish translations for PROJECT.
# Copyright (C) 2021 ORGANIZATION
# This file is distributed under the same license as the PROJECT project.
# FIRST AUTHOR <EMAIL@ADDRESS>, 2021.
#
msgid ""
msgstr ""
"Project-Id-Version: PROJECT VERSION\n"
"Report-Msgid-Bugs-To: EMAIL@ADDRESS\n"
"POT-Creation-Date: 2021-06-29 23:23-0700\n"
"PO-Revision-Date: 2021-06-29 23:25-0700\n"
"Last-Translator: FULL NAME <EMAIL@ADDRESS>\n"
"Language: es\n"
"Language-Team: es <LL@li.org>\n"
"Plural-Forms: nplurals=2; plural=(n != 1)\n"
"MIME-Version: 1.0\n"
"Content-Type: text/plain; charset=utf-8\n"
"Content-Transfer-Encoding: 8bit\n"
"Generated-By: Babel 2.5.1\n"

#: app/email.py:21
msgid "[Microblog] Reset Your Password"
msgstr ""

#: app/forms.py:12 app/forms.py:19 app/forms.py:50
msgid "Username"
msgstr ""

#: app/forms.py:13 app/forms.py:21 app/forms.py:43
msgid "Password"
msgstr ""

If you skip the header, you can see that what follows is a list of strings that were extracted from the _() and _l() calls. For each text, you get a reference to the location of the text in your application. Then the msgid line contains the text in the base language, and the msgstr line that follows contains an empty string. Those empty strings need to be edited to have the version of the text in the target language.

There are many translation applications that work with .po files. If you feel comfortable editing the text file, then that's sufficient, but if you are working with a large project it may be recommended to work with a specialized editor. The most popular translation application is the open-source poedit, which is available for all major operating systems. If you are familiar with vim, then the po.vim plugin gives some key mappings that make working with these files easier.

Below you can see a portion of the Spanish messages.po after I added the translations:

#: app/email.py:21
msgid "[Microblog] Reset Your Password"
msgstr "[Microblog] Nueva Contraseña"

#: app/forms.py:12 app/forms.py:19 app/forms.py:50
msgid "Username"
msgstr "Nombre de usuario"

#: app/forms.py:13 app/forms.py:21 app/forms.py:43
msgid "Password"
msgstr "Contraseña"

The download package for this chapter also contains this file with all the translations in place, so that you don't have to worry about that part for this application.

The messages.po file is a sort of source file for translations. When you want to start using these translated texts, this file needs to be compiled into a format that is efficient to be used by the application at run-time. To compile all the translations for the application, you can use the pybabel compile command as follows:

(venv) $ pybabel compile -d app/translations
compiling catalog app/translations/es/LC_MESSAGES/messages.po to
app/translations/es/LC_MESSAGES/messages.mo

This operation adds a messages.mo file next to messages.po in each language repository. The .mo file is the file that Flask-Babel will use to load translations for the application.

After you create the messages.mo file for Spanish or any other languages you added to the project, these languages are ready to be used in the application. If you want to see how the application looks in Spanish, you can edit the language configuration in your web browser to have Spanish as the preferred language. For Chrome, this is the Advanced part of the Settings page:

Chrome Language Options

If you prefer not to change your browser settings, the other alternative is to force a language by making the localeselector function always return it. For Spanish, this would be how you would do it:

app/__init__.py: Select best language.

@babel.localeselector
def get_locale():
    # return request.accept_languages.best_match(app.config['LANGUAGES'])
    return 'es'

Running the application with the browser configured for Spanish, or the localeselector function returning es will make all the texts appear in Spanish when you use the application.

Updating the Translations

One common situation when working with translations is that you may want to start using a translation file even if it is incomplete. That is totally fine, you can compile an incomplete messages.po file and any translations that are available will be used, while any missing ones will use the base language. You can then continue working on the translations and compile again to update the messages.mo file as you make progress.

Another common scenario occurs if you missed some texts when you added the _() wrappers. In this case you are going to see that those texts that you missed are going to remain in English, because Flask-Babel knows nothing about them. In this situation you'll want to add the _() or _l() wrappers when you detect texts that don't have them, and then do an update procedure, which involves two steps:

(venv) $ pybabel extract -F babel.cfg -k _l -o messages.pot .
(venv) $ pybabel update -i messages.pot -d app/translations

The extract command is identical to the one I issued earlier, but now it will generate a new version of messages.pot with all the previous texts plus anything new that you recently wrapped with _() or _l(). The update call takes the new messages.pot file and merges it into all the messages.po files associated with the project. This is going to be an intelligent merge, in which any existing texts will be left alone, while only entries that were added or removed in messages.pot will be affected.

After the messages.po are updated, you can go ahead and translate any new tests, then compile the messages one more time to make them available to the application.

Translating Dates and Times

Now I have a complete Spanish translation for all the texts in Python code and templates, but if you run the application in Spanish and are a good observer, you will notice that there are still a few things that appear in English. I'm referring to the timestamps generated by Flask-Moment and moment.js, which obviously have not been included in the translation effort because none of the texts generated by these packages are part of the source code or templates of the application.

The moment.js library does support localization and internationalization, so all I need to do is configure the proper language. Flask-Babel returns the selected language and locale for a given request via the get_locale() function, so what I'm going to do is add the locale to the g object, so that I can then access it from the base template:

app/routes.py: Store selected language in flask.g.

# ...
from flask import g
from flask_babel import get_locale

# ...

@app.before_request
def before_request():
    # ...
    g.locale = str(get_locale())

The get_locale() function from Flask-Babel returns a locale object, but I just want to have the language code, which can be obtained by converting the object to a string. Now that I have g.locale, I can access it from the base template to configure moment.js with the correct language:

app/templates/base.html: Set locale for moment.js.

...
{% block scripts %}
    {{ super() }}
    {{ moment.include_moment() }}
    {{ moment.lang(g.locale) }}
{% endblock %}

And now all dates and times should appear in the same language as the text. Below you can see how the application looks in Spanish:

Microblog in Español

At this point, all texts except those that were provided by the user in blog posts or profile descriptions should be translatable into other languages.

Command-Line Enhancements

You will probably agree with me that the pybabel commands are a bit long and difficult to remember. I'm going to use this opportunity to show you how you can create custom commands that are integrated with the flask command. So far, you've seen me use flask run, flask shell, and several flask db sub-commands provided by the Flask-Migrate extension. It is actually easy to add application-specific commands to flask as well. So what I'm going to do now is create a few simple commands that trigger the pybabel commands with all the arguments that are specific to this application. The commands that I'm going to add are:

  • flask translate init LANG to add a new language
  • flask translate update to update all language repositories
  • flask translate compile to compile all language repositories

The babel export step is not going to be a command, because generating the messages.pot file is always a pre-requisite to running either the init or the update commands, so the implementation of these commands will generate the translation template file as a temporary file.

Flask relies on Click for all its command-line operations. Commands like translate, which are a root for several sub-commands are created via the app.cli.group() decorator. I'm going to put these commands in a new module called app/cli.py:

app/cli.py: Translate command group.

from app import app

@app.cli.group()
def translate():
    """Translation and localization commands."""
    pass

The name of the command comes from the name of the decorated function, and the help message comes from the docstring. Since this is a parent command that only exists to provide a base for the sub-commands, the function itself does not need to do anything.

The update and compile are easy to implement, because they do not take any arguments:

app/cli.py: Update and compile sub-commands.

import os

# ...

@translate.command()
def update():
    """Update all languages."""
    if os.system('pybabel extract -F babel.cfg -k _l -o messages.pot .'):
        raise RuntimeError('extract command failed')
    if os.system('pybabel update -i messages.pot -d app/translations'):
        raise RuntimeError('update command failed')
    os.remove('messages.pot')

@translate.command()
def compile():
    """Compile all languages."""
    if os.system('pybabel compile -d app/translations'):
        raise RuntimeError('compile command failed')

Note how the decorator from these functions is derived from the translate parent function. This may seem confusing, since translate() is a function, but it is the standard way in which Click builds groups of commands. Same as with the translate() function, the docstrings for these functions are used as help message in the --help output.

You can see that for all commands, I run them and make sure that the return value is zero, which implies that the command did not return any error. If the command errors, then I raise a RuntimeError, which will cause the script to stop. The update() function combines the extract and update steps in the same command, and if everything is successful, it deletes the messages.pot file after the update is complete, since this file can be easily regenerated when needed again.

The init command takes the new language code as an argument. Here is the implementation:

app/cli.py: Init sub-command.

import click

@translate.command()
@click.argument('lang')
def init(lang):
    """Initialize a new language."""
    if os.system('pybabel extract -F babel.cfg -k _l -o messages.pot .'):
        raise RuntimeError('extract command failed')
    if os.system(
            'pybabel init -i messages.pot -d app/translations -l ' + lang):
        raise RuntimeError('init command failed')
    os.remove('messages.pot')

This command uses the @click.argument decorator to define the language code. Click passes the value provided in the command to the handler function as an argument, and then I incorporate the argument into the init command.

The final step to enable these commands to work is to import them, so that the commands get registered. I decided to do this in the microblog.py file in the top-level directory:

microblog.py: Register command-line commands.

from app import cli

Here the only thing I need to do is import the new cli.py module, there is no need to do anything with it, as the import causes the command decorators to run and register the command.

At this point, running flask --help will list the translate command as an option. And flask translate --help will show the three sub-commands that I defined:

(venv) $ flask translate --help
Usage: flask translate [OPTIONS] COMMAND [ARGS]...

  Translation and localization commands.

Options:
  --help  Show this message and exit.

Commands:
  compile  Compile all languages.
  init     Initialize a new language.
  update   Update all languages.

So now, the workflow is much simpler and there is no need to remember long and complicated commands. To add a new language, you use:

(venv) $ flask translate init <language-code>

To update all the languages after making changes to the _() and _l() language markers:

(venv) $ flask translate update

And to compile all languages after updating the translation files:

(venv) $ flask translate compile

198 comments

  • #101 Hassan said 2020-01-14T00:21:16Z

    Hello, again.

    There is another issue with the interface concerning RLT website which is that the whole interface should be mirror-imaged, so the Brand should go to the Right-most side of the nav-bar and the link should go to the most left side part of the page. The whole page links main area and sidebar areas if present should be mirror-imaged as well. Does flask-bootstrap solve these issues? Should I add some metas to the html head tag to do such tasks? In Wordpress for instance the rtl.css achieves this purpose. I wonder how to do it in flask?.

    Thanks in advance.

  • #102 Miguel Grinberg said 2020-01-14T11:40:55Z

    @Hassan: Flask is not concerned with how your web pages look, and Flask-Babel is only concerned about translations. This project uses the Bootstrap CSS/JS library, and there are extensions for it that support right-to-left languages. You have to enhance your base template so that it supports the RTL mode, either using an extension, or implementing the CSS changes yourself.

  • #103 Xinyu said 2020-02-21T11:40:17Z

    Hi Miguel, Thank you for the excellent tutorial!

    Babel is apparently the standard method for internationalization for flask. But it is not trivial to use. It also impacts on building scripts (e.g. if you use container) and on adding (or not adding) files (.po, .mo, etc.) into repository.

    The "classic" method (also used in other program languages) is using key-value pairs. These pairs are saved in files for every language. For example, if you want to translate "username" into spanish, you just call, say, translate("username", "es"). You just implement the method "translate", which looks up the file, say, "language.es" and finds the key "username" and returns the string representing the word "username" in spanish. In the py and html files you don't write message directly, but use the key.

    So my question is, what is the advantages of babel over this "classic" method, which you don't need any extension?

  • #104 Miguel Grinberg said 2020-02-21T23:57:25Z

    @Xinyu: babel is a wrapper for gettext, which is a fairly well known standard translation utility for Unix systems that has been in use for about 30 years. In my view that is the classic way of doing translations. Using a dictionary is a homegrown solution that is not as flexible. For example, you would not get placeholders or pluralization if you use your own dictionaries.

  • #105 Taco Scheltema said 2020-02-27T12:42:00Z

    Hi Miguel, thanks for the great tutorial!

    I noticed that messages from flask-login aren't translated. I managed to find a solution for this: In the flask-login documentation there is a section on localization: https://flask-login.readthedocs.io/en/latest/#localization which mentions setting up a function. I've implemented the following:

    in forms.py I added from app import login

    in the LoginForm class I added login.localize_callback = _

    then in my messages.po file I added msgid "Please log in to access this page." msgstr "Log in om de inhoud van deze pagina te zien."

    which translates the message for me. The only thing I haven't worked out is how to prevent this from being commented out after an pybabel update. Any ideas?

  • #106 Miguel Grinberg said 2020-02-28T08:30:00Z

    @Taco: Yeah, to make it work properly you need to include those strings from Flask-Login in your code, so that they are found when babel generates the language dictionaries. Add them to a dummy python module in your project, for example.

  • #107 Tom said 2020-03-09T11:37:26Z

    Hi Miguel,

    I initialised the package, added the LANGUAGES to config.py and the localeselector to init.py. Then I tagged everything an generated a messages.po and it looked like yours, no errors. Now I set my browser to English (I'm translating from German to English), but it does not work, everything is still in German and working the exact same way as before. I'm clueless... Where could the problem be?

  • #108 Jimmy Lin said 2020-03-10T01:59:50Z

    I'm currently evaluating the best structure for managing I18N and besides detecting the user language, there is also an option to use URL parameters to set. Based on this Google article, they recommend using a URL param instead of auto-detection - https://support.google.com/webmasters/answer/182192?hl=en. I wonder what your thoughts are Miguel, and if you'd consider providing a tutorial for using locale-specific URLs?

  • #109 Miguel Grinberg said 2020-03-10T10:36:32Z

    @Tom: did you manually write all the translations in English? This isn't automatic, you have to have the translations manually done. In this tutorial I include Spanish translations for the entire application in addition to the original English texts. If you started with German, now you need to create an English translation.

  • #110 kristijan said 2020-03-10T11:28:14Z

    Thank you for the material and the knowledge you have .... thank you very much, I bought a few courses at home, which I paid $ 50 for but none of them are this good.

  • #111 Miguel Grinberg said 2020-03-10T11:37:02Z

    @kristijan: the solution you refer to isn't that different to mine. In my proposed solution I decide what language to use based on the value of the Accept-Language header. This other implementation uses a query string argument instead. In both cases information that is provided in the request object is used, so the changes to switch to query string are minimal and limited to a small change in the localeselector function.

  • #112 Mohit said 2020-04-23T22:29:00Z

    Thank you for the great tutorial. The best intro to Backend Development one can ask for. I have a query, I think we never explicitly mentioned to translate the error messages of form validators, but those messages are also being translated. If I'm correct, how is it happening? Is it something underneath the wtf.forms? Or If I'm wrong, where are we translating the text? I checked that we are not translating the flash messages in base.html Please Clarify.

  • #113 Miguel Grinberg said 2020-04-24T14:27:58Z

    @Mohit: The wtforms package has translations for a lot of languages. See https://github.com/wtforms/wtforms/tree/master/src/wtforms/locale.

  • #114 Thomas Altfather-Good said 2020-05-13T17:59:23Z

    The flask update and compile sequence results in fractured German unless I manually edit messages.po. Once I did that and reran compile "TAG said vor 19 Tagen" rendered correctly as "TAG sagte vor 19 Tagen". I assume this is kind of std behaviour. I suppose babel has some difficulty with verb declension (?)

  • #115 Miguel Grinberg said 2020-05-14T22:35:17Z

    @Thomas: Babel does not understand language at all, it relies on the translations created manually.

  • #116 Luisangel Marcia said 2020-06-04T04:38:23Z

    Hello Miguel, i have fixed with success my last error. I would like to know if you could know why would the flask commands with translate doesn't get me recognize trough terminal even if I had it implemented as you do. This is the error that shows me.

    [2020-06-03 22:37:52,994] INFO in init: Microblog startup Usage: flask [OPTIONS] COMMAND [ARGS]... Try 'flask --help' for help.

    Error: No such command 'translate'.

  • #117 Miguel Grinberg said 2020-06-04T09:29:50Z

    @Luisangel: do you have your FLASK_APP environment variable set?

  • #118 Joshua Muwanguzi said 2020-06-17T11:51:51Z

    hey Miguel, thanks so much for the course. Up until this point, I just realised we have an Emptyform class. Is it a new commit or it's just me who hadn't seen it. If it's, why are we using it? I also have an issue with my follow and unfollow functions, whenever I click either of them, I get 'type error, 'User' object is not subscriptable'. My program has been building fine until recently. What could be the problem now?

  • #119 Miguel Grinberg said 2020-06-22T23:10:17Z

    @Joshua: this was a recent improvement I've made. The EmptyForm class appears in Part 8, the Followers chapter.

  • #120 Guido said 2020-06-26T17:17:29Z

    Hi Miguel,

    thank you once again for the great tutorial. I would like to add more CLI commands - say, to add standard users like admin, demo, etc. How should I better create other CLI command group - in the same "register" function?

    Thanks a lot, Guido

    PS Some examples are here; https://flask.palletsprojects.com/en/1.1.x/cli/#custom-commands

  • #121 Miguel Grinberg said 2020-06-26T23:00:18Z

    @Guido: I don't understand what part you need help with. You can add any commands that you like, just follow the same structure I used here for the translation commands.

  • #122 Jesse said 2020-07-02T15:25:37Z

    Hi Miguel,

    I love the tutorial series, thanks for making it so clear. I'm getting an error after I enter the extract command for babel in my terminal the first time. It is referring to a tokenize error, but doesn't refer to any of my code files, so I'm not sure where I should go to look for any issues.

    My errror print out is as follows:

    extracting messages from app/init.py extracting messages from app/email.py extracting messages from app/errors.py extracting messages from app/forms.py extracting messages from app/models.py extracting messages from app/routes.py Traceback (most recent call last): File "/home/jesse/PycharmProjects/flask_app_2020/venv/bin/pybabel", line 8, in <module> sys.exit(main()) File "/home/jesse/PycharmProjects/flask_app_2020/venv/lib/python3.8/site-packages/babel/messages/frontend.py", line 929, in main return CommandLineInterface().run(sys.argv) File "/home/jesse/PycharmProjects/flask_app_2020/venv/lib/python3.8/site-packages/babel/messages/frontend.py", line 853, in run return cmdinst.run() File "/home/jesse/PycharmProjects/flask_app_2020/venv/lib/python3.8/site-packages/babel/messages/frontend.py", line 481, in run for filename, lineno, message, comments, context in extracted: File "/home/jesse/PycharmProjects/flask_app_2020/venv/lib/python3.8/site-packages/babel/messages/extract.py", line 149, in extract_from_dir for message_tuple in check_and_call_extract_file( File "/home/jesse/PycharmProjects/flask_app_2020/venv/lib/python3.8/site-packages/babel/messages/extract.py", line 207, in check_and_call_extract_file for message_tuple in extract_from_file( File "/home/jesse/PycharmProjects/flask_app_2020/venv/lib/python3.8/site-packages/babel/messages/extract.py", line 243, in extract_from_file return list(extract(method, fileobj, keywords, comment_tags, File "/home/jesse/PycharmProjects/flask_app_2020/venv/lib/python3.8/site-packages/babel/messages/extract.py", line 325, in extract for lineno, funcname, messages, comments in results: File "/home/jesse/PycharmProjects/flask_app_2020/venv/lib/python3.8/site-packages/babel/messages/extract.py", line 418, in extract_python for tok, value, (lineno, ), , _ in tokens: File "/usr/lib/python3.8/tokenize.py", line 521, in _tokenize raise TokenError("EOF in multi-line statement", (lnum, 0)) tokenize.TokenError: ('EOF in multi-line statement', (203, 0))

  • #123 Miguel Grinberg said 2020-07-02T21:53:02Z

    @Jesse: this is caused by having a syntax error in the code, I think. The message extraction does some parsing of the Python code so it errors if the code has errors. Based on the error I think you need to check line 203 of routes.py, where you'll find a missing quote, if I'm not mistaken.

  • #124 Filipe Bezerra said 2020-07-05T18:44:49Z

    I've following along with this mega tutorial day by day and I can't say enough how I'm grateful for your effort and commitment here with this tutorial and with the python community @MiguelGrinberg.

    By the way, my congratulations organizing the FlaskConf, thank you and to all others organizers.

    I had to make a change in my Config file to work with specific languages, so for anyone having trouble with that, here what I've done:

    class Config(object): #... LANGUAGES = ['en_US', 'es', 'pt_BR']

  • #125 Md. Tanvir Foysal said 2020-08-03T14:53:59Z

    (venv) G:\microblog>cat babel.cfg 'cat' is not recognized as an internal or external command, operable program or batch file.

    What is the problem Miguel?

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