flask_script.py

# -*- coding: utf-8 -*-
from __future__ import absolute_import
from __future__ import with_statement

import os
import sys
import code
import string
import getpass
import inspect
import warnings

import argparse

from flask import Flask, _request_ctx_stack

__all__ = ["Command", "Shell", "Server", "Manager", "Option",
           "prompt", "prompt_pass", "prompt_bool", "prompt_choices"]


def prompt(name, default=None):

    """
    Grab user input from command line.

    :param name: prompt text
    :param default: default value if no input provided.
    """

    prompt = name + (default and ' [%s]' % default or '')
    prompt += name.endswith('?') and ' ' or ': '
    while True:
        rv = raw_input(prompt)
        if rv:
            return rv
        if default is not None:
            return default


def prompt_pass(name, default=None):

    """
    Grabs hidden (password) input from command line.

    :param name: prompt text
    :param default: default value if no input provided.
    """

    prompt = name + (default and ' [%s]' % default or '')
    prompt += name.endswith('?') and ' ' or ': '
    while True:
        rv = getpass.getpass(prompt)
        if rv:
            return rv
        if default is not None:
            return default


def prompt_bool(name, default=False, yes_choices=None, no_choices=None):

    """
    Grabs user input from command line and converts to boolean
    value.

    :param name: prompt text
    :param default: default value if no input provided.
    :param yes_choices: default 'y', 'yes', '1', 'on', 'true', 't'
    :param no_choices: default 'n', 'no', '0', 'off', 'false', 'f'
    """

    yes_choices = yes_choices or ('y', 'yes', '1', 'on', 'true', 't')
    no_choices = no_choices or ('n', 'no', '0', 'off', 'false', 'f')

    while True:
        rv = prompt(name + '?', default and yes_choices[0] or no_choices[0])
        if not rv:
            return default
        if rv.lower() in yes_choices:
            return True
        elif rv.lower() in no_choices:
            return False


def prompt_choices(name, choices, default=None, resolve=string.lower,
                   no_choice=('none',)):

    """
    Grabs user input from command line from set of provided choices.

    :param name: prompt text
    :param choices: list or tuple of available choices. Choices may be
                    single strings or (key, value) tuples.
    :param default: default value if no input provided.
    :param no_choice: acceptable list of strings for "null choice"
    """

    _choices = []
    options = []

    for choice in choices:
        if isinstance(choice, basestring):
            options.append(choice)
        else:
            options.append("%s [%s]" % (choice[1], choice[0]))
            choice = choice[0]
        _choices.append(choice)

    while True:
        rv = prompt(name + '? - (%s)' % ', '.join(options), default)
        if not rv:
            return default
        rv = resolve(rv)
        if rv in no_choice:
            return None
        if rv in _choices:
            return rv


class Option(object):

    """
    Stores positional and optional arguments for `ArgumentParser.add_argument
    <http://argparse.googlecode.com/svn/trunk/doc/add_argument.html>`_.

    :param name_or_flags: Either a name or a list of option strings,
                          e.g. foo or -f, --foo
    :param action: The basic type of action to be taken when this argument
                   is encountered at the command-line.
    :param nargs: The number of command-line arguments that should be consumed.
    :param const: A constant value required by some action and nargs selections.
    :param default: The value produced if the argument is absent from
                    the command-line.
    :param type: The type to which the command-line arg should be converted.
    :param choices: A container of the allowable values for the argument.
    :param required: Whether or not the command-line option may be omitted
                     (optionals only).
    :param help: A brief description of what the argument does.
    :param metavar: A name for the argument in usage messages.
    :param dest: The name of the attribute to be added to the object
                 returned by parse_args().
    """

    def __init__(self, *args, **kwargs):
        self.args = args
        self.kwargs = kwargs


class Command(object):

    """
    Base class for creating commands.
    """

    option_list = []

    @property
    def description(self):
        description = self.__doc__ or ''
        return description.strip()

    def add_option(self, option):

        """
        Adds Option to option list.
        """

        self.option_list.append(option)

    def get_options(self):

        """
        By default, returns self.option_list.Override if you
        need to do instance-specific configuration.
        """

        return self.option_list

    def create_parser(self, prog):
        parser = argparse.ArgumentParser(prog=prog,
                                         description=self.description)

        for option in self.get_options():
            parser.add_argument(*option.args, **option.kwargs)

        return parser

    def handle(self, app, *args, **kwargs):
        """
        Handles the command with given app. Default behaviour is to call within
        a test request context.
        """
        with app.test_request_context():
            return self.run(*args, **kwargs)

    def run(self):

        """
        Runs a command. This must be implemented by the subclass. Should take
        arguments as configured by the Command options.
        """

        raise NotImplementedError

    def prompt(self, name, default=None):
        warnings.warn_explicit(
            "Command.prompt is deprecated, use prompt() function instead")

        prompt(name, default)

    def prompt_pass(self, name, default=None):
        warnings.warn_explicit(
            "Command.prompt_pass is deprecated, use prompt_pass() function "
            "instead")

        prompt_pass(name, default)

    def prompt_bool(self, name, default=False):
        warnings.warn_explicit(
            "Command.prompt_bool is deprecated, use prompt_bool() function "
            "instead")

        prompt_bool(name, default)

    def prompt_choices(self, name, choices, default=None):
        warnings.warn_explicit(
            "Command.choices is deprecated, use prompt_choices() function "
            "instead")

        prompt_choices(name, choices, default)


class Shell(Command):
    """
    Runs a Python shell inside Flask application context.

    :param banner: banner appearing at top of shell when started
    :param make_context: a callable returning a dict of variables
                         used in the shell namespace. By default
                         returns a dict consisting of just the app.
    :param use_ipython: use IPython shell if available, ignore if not.
                        The IPython shell can be turned off in command
                        line by passing the **--no-ipython** flag.
    """

    banner = ''

    description = 'Runs a Python shell inside Flask application context.'

    def __init__(self, banner=None, make_context=None, use_ipython=True):

        self.banner = banner or self.banner
        self.use_ipython = use_ipython

        if make_context is None:
            make_context = lambda: dict(app=_request_ctx_stack.top.app)

        self.make_context = make_context

    def get_options(self):

        return (
            Option('--no-ipython',
                action="store_true",
                dest='no_ipython',
                default=not(self.use_ipython)),
        )

    def get_context(self):

        """
        Returns a dict of context variables added to the shell namespace.
        """

        return self.make_context()

    def run(self, no_ipython):

        """
        Runs the shell. Unless no_ipython is True or use_python is False
        then runs IPython shell if that is installed.
        """

        context = self.get_context()
        if not no_ipython:
            try:
                import IPython
                try:
                    sh = IPython.Shell.IPShellEmbed(banner=self.banner)
                except AttributeError:
                    sh = IPython.frontend.terminal.embed.InteractiveShellEmbed(banner1=self.banner)
                sh(global_ns=dict(), local_ns=context)
                return
            except ImportError:
                pass

        code.interact(self.banner, local=context)


class Server(Command):

    """
    Runs the Flask development server i.e. app.run()

    :param host: server host
    :param port: server port
    :param use_debugger: if False, will no longer use Werkzeug debugger.
                         This can be overriden in the command line
                         by passing the **-d** flag.
    :param use_reloader: if False, will no longer use auto-reloader.
                         This can be overriden in the command line by
                         passing the **-r** flag.
    :param threaded: should the process handle each request in a separate
                     thread?
    :param processes: number of processes to spawn
    :param options: :func:`werkzeug.run_simple` options.
    """

    description = 'Runs the Flask development server i.e. app.run()'

    def __init__(self, host='127.0.0.1', port=5000, use_debugger=True,
                 use_reloader=True, threaded=False, processes=1, **options):

        self.port = port
        self.host = host
        self.use_debugger = use_debugger
        self.use_reloader = use_reloader
        self.server_options = options
        self.threaded = threaded
        self.processes = processes

    def get_options(self):

        options = (
            Option('-t', '--host',
                   dest='host',
                   default=self.host),

            Option('-p', '--port',
                   dest='port',
                   type=int,
                   default=self.port),

            Option('--threaded',
                   dest='threaded',
                   action='store_true',
                   default=self.threaded),

            Option('--processes',
                   dest='processes',
                   type=int,
                   default=self.processes),
        )

        if self.use_debugger:
            options += (Option('-d', '--no-debug',
                               action='store_false',
                               dest='use_debugger',
                               default=self.use_debugger),)

        else:
            options += (Option('-d', '--debug',
                               action='store_true',
                               dest='use_debugger',
                               default=self.use_debugger),)

        if self.use_reloader:
            options += (Option('-r', '--no-reload',
                               action='store_false',
                               dest='use_reloader',
                               default=self.use_reloader),)

        else:
            options += (Option('-r', '--reload',
                               action='store_true',
                               dest='use_reloader',
                               default=self.use_reloader),)

        return options

    def handle(self, app, host, port, use_debugger, use_reloader,
               threaded, processes):
        # we don't need to run the server in request context
        # so just run it directly

        app.run(host=host,
                port=port,
                debug=use_debugger,
                use_debugger=use_debugger,
                use_reloader=use_reloader,
                threaded=threaded,
                processes=processes,
                **self.server_options)


class InvalidCommand(Exception):
    pass


class Manager(object):

    """
    Controller class for handling a set of commands.

    Typical usage::

        class Print(Command):

            def run(self):
                print "hello"

        app = Flask(__name__)

        manager = Manager(app)
        manager.add_command("print", Print())

        if __name__ == "__main__":
            manager.run()

    On command line::

        python manage.py print
        > hello

    :param app: Flask instance or callable returning a Flask instance.
    :param with_default_commands: load commands **runserver** and **shell**
                                  by default.
    """

    def __init__(self, app, with_default_commands=True, usage=None):

        self.app = app

        self._commands = dict()
        self._options = list()

        if with_default_commands:
            self.add_default_commands()

        self.usage = usage

    def add_default_commands(self):
        """
        Adds the shell and runserver default commands. To override these
        simply add your own equivalents using add_command or decorators.
        """

        self.add_command("shell", Shell())
        self.add_command("runserver", Server())

    def create_app(self, **kwargs):

        if isinstance(self.app, Flask):
            return self.app

        return self.app(**kwargs)

    def create_parser(self, prog):

        """
        Creates an ArgumentParser instance from options returned
        by get_options(), and a subparser for the given command.
        """

        prog = os.path.basename(prog)
        parser = argparse.ArgumentParser(prog=prog)
        for option in self.get_options():
            parser.add_argument(*option.args, **option.kwargs)

        return parser

    def get_options(self):
        return self._options

    def add_option(self, *args, **kwargs):
        """
        Adds an application-wide option. This is useful if you want to set
        variables applying to the application setup, rather than individual
        commands.

        For this to work, the manager must be initialized with a factory
        function rather than an instance. Otherwise any options you set will
        be ignored.

        The arguments are then passed to your function, e.g.::

            def create_app(config=None):
                app = Flask(__name__)
                if config:
                    app.config.from_pyfile(config)

                return app

            manager = Manager(create_app)
            manager.add_option("-c", "--config", dest="config", required=False)

        and are evoked like this::

            > python manage.py -c dev.cfg mycommand

        Any manager options passed in the command line will not be passed to
        the command.

        Arguments for this function are the same as for the Option class.
        """

        self._options.append(Option(*args, **kwargs))

    def command(self, func):
        """
        Adds a command function to the registry.

        :param func: command function.Arguments depend on the
                     options.

        """

        args, varargs, keywords, defaults = inspect.getargspec(func)

        options = []

        # first arg is always "app" : ignore

        defaults = defaults or []
        kwargs = dict(zip(*[reversed(l) for l in (args, defaults)]))

        for arg in args:
            if arg in kwargs:

                default = kwargs[arg]

                if isinstance(default, bool):
                    options.append(Option('-%s' % arg[0],
                                          '--%s' % arg,
                                          action="store_true",
                                          dest=arg,
                                          required=False,
                                          default=default))
                else:
                    options.append(Option('-%s' % arg[0],
                                          '--%s' % arg,
                                          dest=arg,
                                          type=unicode,
                                          required=False,
                                          default=default))

            else:
                options.append(Option(arg, type=unicode))

        command = Command()
        command.run = func
        command.__doc__ = func.__doc__
        command.option_list = options

        self.add_command(func.__name__, command)

        return func

    def shell(self, func):
        """
        Decorator that wraps function in shell command. This is equivalent to::

            def _make_context(app):
                return dict(app=app)

            manager.add_command("shell", Shell(make_context=_make_context))

        The decorated function should take a single "app" argument, and return
        a dict.

        For more sophisticated usage use the Shell class.
        """

        self.add_command('shell', Shell(make_context=func))

        return func

    def option(self, *args, **kwargs):

        """
        Decorator to add an option to a function. Automatically registers the
        function - do not use together with ``@command``. You can add as many
        ``@option`` calls as you like, for example::

            @option('-n', '--name', dest='name')
            @option('-u', '--url', dest='url')
            def hello(name, url):
                print "hello", name, url

        Takes the same arguments as the ``Option`` constructor.
        """

        option = Option(*args, **kwargs)

        def decorate(func):
            name = func.__name__

            if name not in self._commands:

                command = Command()
                command.run = func
                command.__doc__ = func.__doc__
                command.option_list = []

                self.add_command(name, command)

            self._commands[name].option_list.append(option)
            return func
        return decorate

    def add_command(self, name, command):

        """
        Adds command to registry.

        :param command: Command instance
        """

        self._commands[name] = command

    def get_usage(self):

        """
        Returns string consisting of all commands and their
        descriptions.
        """
        pad = max(map(len, self._commands.iterkeys())) + 2
        format = '  %%- %ds%%s' % pad

        rv = []

        if self.usage:
            rv.append(self.usage)

        for name, command in sorted(self._commands.iteritems()):
            usage = name
            description = command.description or ''
            usage = format % (name, description)
            rv.append(usage)

        return "\n".join(rv)

    def print_usage(self):

        """
        Prints result of get_usage()
        """

        print self.get_usage()

    def handle(self, prog, name, args=None):

        args = list(args or [])

        try:
            command = self._commands[name]
        except KeyError:
            raise InvalidCommand, "Command %s not found" % name

        help_args = ('-h', '--help')

        # remove -h from args if present, and add to remaining args
        app_args = [a for a in args if a not in help_args]

        app_parser = self.create_parser(prog)
        app_namespace, remaining_args = app_parser.parse_known_args(app_args)
        app = self.create_app(**app_namespace.__dict__)

        for arg in help_args:
            if arg in args:
                remaining_args.append(arg)

        command_parser = command.create_parser(prog + " " + name)
        if getattr(command, 'capture_all_args', False):
            command_namespace, unparsed_args = \
                command_parser.parse_known_args(remaining_args)
            positional_args = [unparsed_args]
        else:
            command_namespace = command_parser.parse_args(remaining_args)
            positional_args = []

        return command.handle(app, *positional_args, **command_namespace.__dict__)

    def run(self, commands=None, default_command=None):

        """
        Prepares manager to receive command line input. Usually run
        inside "if __name__ == "__main__" block in a Python script.

        :param commands: optional dict of commands. Appended to any commands
                         added using add_command().

        :param default_command: name of default command to run if no
                                arguments passed.
        """

        if commands:
            self._commands.update(commands)

        try:

            try:
                command = sys.argv[1]
            except IndexError:
                command = default_command

            if command is None:
                raise InvalidCommand, "Please provide a command"

            result = self.handle(sys.argv[0], command, sys.argv[2:])

            sys.exit(result or 0)

        except InvalidCommand, e:
            print e
            self.print_usage()

        sys.exit(1)