API Docs¶

Flask extension to dynamically assemble your Flask application from packages.

Flask-Registry is initialized like this:

>>> from flask import Flask
>>> from flask_registry import Registry, ListRegistry
>>> app = Flask('myapp')
>>> r = Registry(app=app)

A simple usage example of ListRegistry looks like this:

>>> app.extensions['registry']['my.namespace'] = ListRegistry()
>>> len(app.extensions['registry'])
1
>>> app.extensions['registry']['my.namespace'].register("something")
>>> app.extensions['registry']['my.namespace'].register("something else")
>>> len(app.extensions['registry']['my.namespace'])
2
>>> for obj in app.extensions['registry']['my.namespace']:
...     print(obj)
something
something else

class flask_registry.Registry(app=None)¶

Bases: _abcoll.MutableMapping

Flask extension.

Initialization of the extension:

>>> from flask import Flask
>>> from flask_registry import Registry
>>> app = Flask('myapp')
>>> r = Registry(app)
>>> app.extensions['registry']
<Registry ()>

or alternatively using the factory pattern:

>>> app = Flask('myapp')
>>> r = Registry()
>>> r.init_app(app)
>>> r
<Registry ()>

init_app(app)¶

Initialize a Flask application.

Only one Registry per application is allowed.

Parameters:	app (flask.Flask) – Flask application
Raises:	flask_registry.RegistryError – if the registry is already initialized

class flask_registry.RegistryProxy(namespace, registry_class, *args, **kwargs)¶

Bases: werkzeug.local.LocalProxy

Lazy proxy object to a registry in the current_app

Allows you to define a registry in your local module without needing to initialize it first. Once accessed the first time, the registry will be initialized in the current_app, thus you must be working in either the Flask application context or request context.

>>> from flask import Flask
>>> app = Flask('myapp')
>>> from flask_registry import Registry, RegistryProxy, RegistryBase
>>> r = Registry(app=app)
>>> proxy = RegistryProxy('myns', RegistryBase)
>>> 'myns' in app.extensions['registry']
False
>>> with app.app_context():
...     print(proxy.namespace)
...
myns
>>> 'myns' in app.extensions['registry']
True

Parameters:	namespace – Namespace for registry registry_class – The registry class - i.e. a sublcass of `RegistryBase`. args – Arguments passed to `registry_class` on initialization. kwargs – Keyword arguments passed to `registry_class` on initialization.

class flask_registry.RegistryError¶

Bases: exceptions.Exception

Exception class raised for user errors.

e.g. creating two registries in the same namespace)

Registry base module.

class flask_registry.base.RegistryBase¶

Bases: object

Abstract base class for all registries.

Each subclass must implement the register() method. Each subclass may implement the unregister() method.

Once a registry is registered in the Flask application, the namespace under which it is available is injected into it self.

Please see flask_registry.registries.core for simple examples of subclasses.

namespace¶: Namespace. Used only by the Flask extension to inject the namespace under which this instance is registered in the Flask application. Defaults to None if not registered in a Flask application.

register(*args, **kwargs)¶: Abstract method which MUST be overwritten by subclasses. A subclass does not need to take the same number of arguments as the abstract base class.

unregister(*args, **kwargs)¶: Abstract method which MAY be overwritten by subclasses. A subclass does not need to take the same number of arguments as the abstract base class.

Core registries.

Core Registries¶

The core registries are useful to use as subclasses for other more advanced registries. The provide the basic functionality for list and dict style registries, as well as simple import path and module style registries.

class flask_registry.registries.core.ListRegistry¶

Bases: flask_registry.base.RegistryBase, _abcoll.Sequence

Basic registry that just keeps a list of objects.

Provides normal list-style access to the registry:

>>> from flask import Flask
>>> from flask_registry import Registry, ListRegistry
>>> app = Flask('myapp')
>>> r = Registry(app=app)
>>> r['myns'] = ListRegistry()
>>> r['myns'].register("something")
>>> len(r['myns'])
1
>>> r['myns'][0]
'something'
>>> "something" in r['myns']
True
>>> for obj in r['myns']:
...     print(obj)
something

register(item)¶

Register a new object

Parameters:	item – Object to register

unregister(item)¶

Unregister an existing object. Raises a ValueError in case object does not exists. If the same object was registered twice, only the first registered object will be unregister.

Parameters:	item – Object to unregister

class flask_registry.registries.core.DictRegistry¶

Bases: flask_registry.base.RegistryBase, _abcoll.MutableMapping

Basic registry that just keeps a key, value pairs.

Provides normal dict-style access to the registry:

>>> from flask import Flask
>>> from flask_registry import Registry, DictRegistry
>>> app = Flask('myapp')
>>> r = Registry(app=app)
>>> r['myns'] = DictRegistry()
>>> r['myns'].register("mykey", "something")
>>> len(r['myns'])
1
>>> r['myns']["mykey"]
'something'
>>> "mykey" in r['myns']
True
>>> for k, v in r['myns'].items():
...     print("%s: %s" % (k,v))
mykey: something

register(key, value)¶

Register a new object under a given key.

Parameters:	key – Key to register object under item – Object to register

unregister(key)¶: Unregister an object under a given key. Raises KeyError in case the given key doesn’t exists.

class flask_registry.registries.core.SingletonRegistry¶

Bases: flask_registry.base.RegistryBase

Basic registry that just keeps a single object.

>>> from flask import Flask
>>> from flask_registry import Registry, SingletonRegistry
>>> app = Flask('myapp')
>>> r = Registry(app=app)
>>> r['singleton'] = SingletonRegistry()
>>> r['singleton'].register("test string")
>>> r['singleton'].get()
'test string'
>>> r['singleton'].register("another string")
Traceback (most recent call last):
    ...
RegistryError: Object already registered.
>>> r['singleton'].unregister()
>>> r['singleton'].get() is None
True
>>> r['singleton'].unregister()
Traceback (most recent call last):
    ...
RegistryError: No object to unregister.

get()¶: Get the registered object

register(obj)¶

Register a new singleton object

Parameters:	obj – The object to register

unregister()¶: Unregister the singleton object

class flask_registry.registries.core.ImportPathRegistry(initial=None, exclude=None, load_modules=False)¶

Bases: flask_registry.registries.core.ListRegistry

Registry of Python import paths.

Supports simple discovery of modules without loading them.

>>> from flask import Flask
>>> from flask_registry import Registry, ImportPathRegistry
>>> app = Flask('myapp')
>>> r = Registry(app=app)
>>> r['myns'] = ImportPathRegistry(initial=[
... 'flask_registry.registries.*',
... 'flask_registry'])
>>> for imp_path in r['myns']:
...     print(imp_path)
flask_registry.registries.appdiscovery
flask_registry.registries.core
flask_registry.registries.modulediscovery
flask_registry.registries.pkgresources
flask_registry

When using star imports it is sometimes useful to exclude certain imports:

>>> r['myns2'] = ImportPathRegistry(
... initial=['flask_registry.registries.*',     ],
... exclude=['flask_registry.registries.core']
... )
>>> for imp_path in r['myns2']:
...     print(imp_path)
flask_registry.registries.appdiscovery
flask_registry.registries.modulediscovery
flask_registry.registries.pkgresources

Parameters:	initial – List of initial import paths. exclude – A list of import paths to not register. Useful together with star imports (`''`). Defaults to `[]`. load_modules* – Load the modules instead of just registering the import path. Defaults to `False`.

register(import_path)¶

Register a new import path.

Parameters:	import_path – A full Python import path (e.g. `somepackge.somemodule`) or Python star import path to find all modules inside a package (e.g. `somepackge.*`).

unregister(*args, **kwargs)¶: It is not possible to unregister import paths.

class flask_registry.registries.core.ModuleRegistry(with_setup=True)¶

Bases: flask_registry.registries.core.ListRegistry

Registry for Python modules with setup and teardown functionality.

Each module may provide a setup() and teardown() function which will be called when the module is registered. The name of the methods can be customized by subclassing and setting the class attributes setup_func_name and teardown_func_name.

Any extra arguments and keyword arguments to register and unregister is passed to the setup and teardown functions.

Example:

import mod

registry = ModuleRegistry(with_setup=True)
registry.register(mod, arg1, arg2, kw1=...)
# Will call mod.setup(arg1, arg2, kw1=...)

Parameters:	with_setup – Call setup/teardown function when registering/unregistering modules. Defaults to `True`.

register(module, *args, **kwargs)¶

TODO.

Parameters:	module – Module to register. args – Argument passed to the module setup function. kwargs – Keyword argument passed to the module setup function.

setup_func_name = 'setup'¶: Name of setup function. Defaults to setup.

teardown_func_name = 'teardown'¶: Name of teardown function. Defaults to teardown.

unregister(module, *args, **kwargs)¶

TODO.

Parameters:	module – Module to unregister. args – Argument passed to the module teardown function. kwargs – Keyword argument passed to the module teardown function.

Application discovery registries.

They provide discovery functionality useful for dynamically constructing Flask applications based on configuration variables. This allows a developer to package config, blueprints and extensions into isolated and reusable packages which a framework can dynamically install into a Flask application.

Such a package (named registry_module) could look like and it is located in tests directory:

registry_module.views – contains blueprints which should be registered on the application object.

registry_module.mockext – contains a setup_app() method which be used to install any Flask extensions on the application object.

registry_module.config – contains configuration variables specific for this module.

Following is a simplified example of a Flask application factory, that will load config, extensions and blueprints:

>>> from flask import Flask, Blueprint
>>> from flask_registry import Registry, PackageRegistry
>>> from flask_registry import ExtensionRegistry
>>> from flask_registry import ConfigurationRegistry
>>> from flask_registry import BlueprintAutoDiscoveryRegistry
>>> class Config(object):
...     PACKAGES = ['registry_module']
...     EXTENSIONS = ['registry_module.mockext']
...     USER_CFG = True
>>> def create_app(config):
...     app = Flask('myapp')
...     app.config.from_object(config)
...     r = Registry(app=app)
...     r['packages'] = PackageRegistry(app)
...     r['extensions'] = ExtensionRegistry(app)
...     r['config'] = ConfigurationRegistry(app)
...     r['blueprints'] = BlueprintAutoDiscoveryRegistry(app=app)
...     return app
>>> config = Config()
>>> app = create_app(config)

Packages¶

The config variable PACKAGES specifies the list of Python packages, which ConfigurationRegistry and BlueprintAutoDiscoveryRegistry will search for config.py and views.py modules inside.

>>> for pkg in app.extensions['registry']['packages']:
...     print(pkg)
registry_module

Extensions¶

The config variable EXTENSIONS specifies the list of Python packages, which the ExtensionRegistry will load and call setup_app(app) on, to dynamically initialize Flask extensions.

>>> for pkg in app.extensions['registry']['extensions']:
...     print(pkg)
registry_module.mockext

Configuration¶

The ConfigurationRegistry will merge any package defined config, with the application config without overwriting already set variables in the application config:

>>> config.USER_CFG
True
>>> import registry_module.config
>>> registry_module.config.USER_CFG
False
>>> app.config['USER_CFG']
True

Blueprints¶

The BlueprintAutoDiscoveryRegistry will search for blueprints defined inside a views module in each package defined in PACKAGES. It will also register the discovered blueprints on the Flask application. Each views module should define either a single blueprint in the variable blueprint and/or multiple blueprints in the variable blueprints:

>>> from registry_module import views
>>> isinstance(views.blueprint, Blueprint)
True
>>> len(views.blueprints)
2
>>> for k in sorted(app.blueprints.keys()):
...     print(k)
test
test1
test2

class flask_registry.registries.appdiscovery.PackageRegistry(app)¶

Bases: flask_registry.registries.core.ImportPathRegistry

Specialized ImportPathRegistry that takes the initial list of import paths from the PACKAGES configuration variable in the application.

Parameters:	app – The Flask application object from which includes a `PACKAGES` variable in it’s configuration.

class flask_registry.registries.appdiscovery.ExtensionRegistry(app)¶

Bases: flask_registry.registries.core.ListRegistry

Flask extensions registry.

Loads all extensions specified by EXTENSIONS configuration variable. The registry will look for a setup_app function in the extension and call it if it exists.

Example configuration:

EXTENSIONS = [
    'invenio.ext.debug_toolbar',
    'invenio.ext.menu:MenuAlchemy',
]

Parameters:	app – Flask application to get configuration from.

register(app, ext_name)¶

Register a Flask extensions and call setup_app() on it.

Parameters:	app – Flask application object ext_name – An import path (e.g. a package, module, object) which when loaded has an method `setup_app()`.

unregister()¶: It is not possible to unregister configuration.

class flask_registry.registries.appdiscovery.ConfigurationRegistry(app, registry_namespace=None)¶

Bases: flask_registry.registries.modulediscovery.ModuleDiscoveryRegistry

Specialized ModuleDiscoveryRegistry that search for config modules in a list of Python packages and merge them into the Flask application config without overwriting already set variables.

Parameters:	app – A Flask application registry_namespace – The registry namespace of an `ImportPathRegistry` with a list Python packages to search for `config` modules in. Defaults to `packages`.

register(new_object)¶

Register a new config module.

Parameters:	new_object – The configuration module. `app.config.from_object()` will be called on it.

unregister(*args, **kwargs)¶: It is not possible to unregister configuration.

class flask_registry.registries.appdiscovery.BlueprintAutoDiscoveryRegistry(module_name=None, app=None, with_setup=False, silent=False)¶

Bases: flask_registry.registries.modulediscovery.ModuleAutoDiscoveryRegistry

Specialized ModuleAutoDiscoveryRegistry that search for views modules in a list of Python packages and register blueprints found inside them.

Blueprints are loaded by searching for a variable blueprints (list of Blueprint instances) or blueprint (a Blueprint instance). If found, the blueprint will be registered on the Flask application.

A blueprint URL prefix can be overwritten using the BLUEPRINTS_URL_PREFIXES variable in the application configuration:

BLUEPRINTS_URL_PREFIXES = {
    '<blueprint name>': '<new url prefix>',
    # ...
}

The module discovery registries.

They provide discovery functionality useful for searching a list of Python packages for a specific module name, and afterwards registering the module. This is used to e.g. load and register Flask blueprints by BlueprintAutoDiscoveryRegistry.

Assume e.g. we want to discover the helpers module from the tests package. First we initialize the registry:

>>> from flask import Flask
>>> from flask_registry import Registry, ModuleDiscoveryRegistry
>>> from flask_registry import ImportPathRegistry
>>> app = Flask('myapp')
>>> r = Registry(app=app)

We then create the list of packages to search through using an ImportPathRegistry:

>>> r['mypackages'] = ImportPathRegistry(initial=['registry_module'])

Then, initialize the ModuleDiscoveryRegistry and run the discovery:

>>> r['mydiscoveredmodules'] = ModuleDiscoveryRegistry(
...     'helpers', registry_namespace='mypackages')
>>> len(r['mydiscoveredmodules'])
0
>>> r['mydiscoveredmodules'].discover(app=app)
>>> len(r['mydiscoveredmodules'])
1

Lazy discovery¶

Using RegistryProxy you may lazily discover modules. Above example using lazy loading looks like this:

>>> from flask_registry import RegistryProxy
>>> app = Flask('myapp')
>>> r = Registry(app=app)
>>> pkg_proxy = RegistryProxy('mypackages', ImportPathRegistry,
...     initial=['registry_module'])
>>> mod_proxy = RegistryProxy('mydiscoveredmodules',
...     ModuleDiscoveryRegistry,
...     'helpers',
...     registry_namespace=pkg_proxy)
>>> 'mypackages' in r
False
>>> 'mydiscoveredmodules' in r
False
>>> with app.app_context():
...     mod_proxy.discover(app=app)
>>> 'mypackages' in r
True
>>> 'mydiscoveredmodules' in r
True

class flask_registry.registries.modulediscovery.ModuleDiscoveryRegistry(module_name, registry_namespace=None, with_setup=False, silent=False)¶

Bases: flask_registry.registries.core.ModuleRegistry

Specialized ModuleRegistry that will search a list of Python packages in an ImportPathRegistry or ModuleRegistry for a specific module name. By default the list of Python packages is read from the packages registry namespace.

Packages may be excluded during the discovery using a configuration variables constructed according to the following pattern:

<NAMESPACE>_<MODULE_NAME>_EXCLUDE

where <NAMESPACE> should be replaced by the registry_namepsace, and <MOUDLE_NAME> should be replaced with module_name. Example: PACKAGES_VIEWS_EXCLUDE. All namespaces are capitalized and have dots replaced with underscores.

Subclasses of ModuleDiscoveryRegistry may overwrite the internal _discover_module() method to provide specialized discovery (see e.g. BlueprintAutoDiscoveryRegistry).

Parameters:

module_name – Name of module to search for in packages.
registry_namespace – The registry namespace of an ImportPathRegistry or ModuleRegistry with a list Python packages to search for module_name modules in. Alternatively to a registry namespace an instance of a RegistryProxy or Registry may also be used. Defaults to packages.
with_setup – Call setup and teardown function on discovered modules. Defaults to False (see ModuleRegistry).
silent – if set to True import errors are ignored. Defaults to False.

discover(app=None)¶

Perform module discovery.

It does so by iterating over the list of Python packages in the order they are specified.

Parameters:	app – Flask application object from where the list of Python packages is loaded (from the `registry_namespace`). Defaults to `current_app` if not specified (thus requires you are working in the Flask application context).

class flask_registry.registries.modulediscovery.ModuleAutoDiscoveryRegistry(module_name, app=None, registry_namespace=None, with_setup=False, silent=False)¶

Bases: flask_registry.registries.modulediscovery.ModuleDiscoveryRegistry

Specialized ModuleDiscoveryRegistry that will discover modules immediately on initialization.

Parameters:

module_name – Name of module to search for in packages.
app – Flask application object
registry_namespace – The registry namespace of an ImportPathRegistry or ModuleRegistry with a list Python packages to search for module_name modules in. Alternatively to a registry namespace an instance of a RegistryProxy or Registry may also be used. Defaults to packages.
with_setup – Call setup and teardown function on discovered modules. Defaults to False (see ModuleRegistry).
silent – if set to True import errors are ignored. Defaults to False.

Package Resources¶

Package resource registries may be used to discover e.g. package resources as well as loading entry points.

Entry points¶

setuptools entry points are a simple way for packages to “advertise” Python objects, so that frameworks can search for these entry points. setup.py files for instance allows you to specify console_scripts entry points, which will install scripts into system path for you.

The EntryPointRegistry allows you to easily register these entry points into your Flask application:

>>> from flask import Flask
>>> from flask_registry import Registry, EntryPointRegistry
>>> app = Flask('myapp')
>>> r = Registry(app=app)
>>> r['scripts'] = EntryPointRegistry('console_scripts')
>>> 'easy_install' in r['scripts']
True

Entry points are specified in you setup.py, e.g.:

setup(
    # ...
    entry_points={
        'flask_registry.test_entry': [
            'testcase = flask_registry:RegistryBase',
        ]
    },
    # ...
)

>>> r['entrypoints'] = EntryPointRegistry(
...     'flask_registry.test_entry', load=True)
>>> 'testcase' in r['entrypoints']
True
>>> from flask_registry import RegistryBase
>>> r['entrypoints']['testcase'][0] == RegistryBase
True

See http://pythonhosted.org/setuptools/pkg_resources.html#entry-points for more information on entry points.

Resource files¶

The PkgResourcesDirDiscoveryRegistry will search a list of Python packages for a specific resource directory and register all files found in the directories.

Assume e.g. a package tests have a directory resources with one file in it called testresource.cfg. This file can be discovered in the following manner:

>>> import os
>>> app = Flask('myapp')
>>> r = Registry(app=app)
>>> from flask_registry import ImportPathRegistry
>>> from flask_registry import PkgResourcesDirDiscoveryRegistry
>>> r['packages'] = ImportPathRegistry(initial=['registry_module'])
>>> r['res'] = PkgResourcesDirDiscoveryRegistry('resources', app=app)
>>> os.path.basename(r['res'][0]) == 'testresource.cfg'
True

class flask_registry.registries.pkgresources.EntryPointRegistry(entry_point_ns, load=True, initial=None, exclude=None, unique=False)¶

Bases: flask_registry.registries.core.DictRegistry

Entry point registry. Based on DictRegistry with keys being the entry point group, and the value being a list of objects referenced by the entry points.

Parameters:	entry_point_ns – Entry point namespace load – if False, entry point will not be loaded. Defaults to `True`. initial – List of initial names. If `None` it defaults to all. exclude – A list of names to not register. Useful together with initial equals to `None`. Defaults to `[]`. unique – Allow only unique options in entry point group if `True`.

register(entry_point)¶

Register a new entry point

Parameters:	entry_point – The entry point

class flask_registry.registries.pkgresources.PkgResourcesDirDiscoveryRegistry(module_name, app=None, registry_namespace=None, with_setup=False, silent=False)¶

Bases: flask_registry.registries.modulediscovery.ModuleAutoDiscoveryRegistry

Specialized ModuleAutoDiscoveryRegistry that will search a list of Python packages in an ImportPathRegistry or ModuleRegistry for a specific resource directory and register all files found in the directories. By default the list of Python packages is read from the packages registry namespace.

API Docs¶

Core Registries¶

Packages¶

Extensions¶

Configuration¶

Blueprints¶

Lazy discovery¶

Package Resources¶

Entry points¶

Resource files¶

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