A relative sqlalchemy path to a sqlite database can be written as:
sqlite:///folder/db_file.db
And an absolute one as:
sqlite:////home/user/folder/db_file.db
Is it possible to write a path relative to home? Like this:
sqlite:///~/folder/db_file.db
Or even better, can the path contain environment variables?
sqlite:////${MY_FOLDER}/db_file.db
This is the context of an alembic.ini file. So if the previous objectives are not possible directly, may I be able to cheat using variable substitution?
[alembic]
script_location = db_versions
sqlalchemy.url = sqlite:///%(MY_FOLDER)s.db
...
I have gone around this issue by modifying the values in the config object just after env.py imports it:
# this is the Alembic Config object, which provides
# access to the values within the .ini file in use.
config = context.config
# import my custom configuration
from my_app import MY_DB_URI
# overwrite the desired value
config.set_main_option("sqlalchemy.url", MY_DB_URI)
Now config.get_main_option("sqlalchemy.url") returns the MY_DB_URI you wanted.
As others have pointed out, one key is 3 slashes for relative, 4 for absolute.
But it took for me than just that...
Had trouble with just a string, I had to do this:
db_dir = "../../database/db.sqlite"
print(f'os.path.abspath(db_dir): {str(os.path.abspath(db_dir))}')
SQLALCHEMY_DATABASE_URI = "sqlite:///" + os.path.abspath(db_dir) # works
# SQLALCHEMY_DATABASE_URI = "sqlite:///" + db_dir # fails
From the alembic documentation (emphasis mine):
sqlalchemy.url - A URL to connect to the database via SQLAlchemy. This configuration value is only used if the env.py file calls upon them; in the “generic” template, the call to config.get_main_option("sqlalchemy.url") in the run_migrations_offline() function and the call to engine_from_config(prefix="sqlalchemy.") in the run_migrations_online() function are where this key is referenced. If the SQLAlchemy URL should come from some other source, such as from environment variables or a global registry, or if the migration environment makes use of multiple database URLs, the developer is encouraged to alter the env.py file to use whatever methods are appropriate in order to acquire the database URL or URLs.
So for this case, the sqlalchemy url format can be circunvented and generated by python itself.
===Update: Using org.reflections:reflections:0.9.11
Looking to use the following line to pull a list of class names from Kotlin source...
Reflections.getSubTypesOf(Any::class.java)
However I receive a message that Kotlin class files aren't being seen when I run the following script...
val classLoader = URLClassLoader(this.getDirectoryUrls(), null)
println("retrieved class loader")
val config = getConfig(classLoader)
println("retrieved source config")
val reflections = Reflections(config)
println("retrieved reflections")
// For 3 paths: Reflections took 3 ms to scan 3 urls, producing 0 keys and 0 values
=== Update: The 3 urls added by "getDirectoryUrls()" are directories containing kotlin class source files.
Below is my config... ideas?
private fun getConfig(classLoader: ClassLoader): ConfigurationBuilder {
val config = ConfigurationBuilder().setUrls(ClasspathHelper.forClassLoader(classLoader))
// .setScanners(SubTypesScanner(false), ResourcesScanner())
if (!packagePath.isNullOrBlank()){
System.out.println("looking in package [$packagePath]")
config.filterInputsBy(FilterBuilder().include(FilterBuilder.prefix(packagePath)))
}
config.addClassLoader(classLoader)
config.setScanners(SubTypesScanner(), TypeAnnotationsScanner())
return config
}
Setting SubTypesScanner(false) seems to be required to get any types with getSubTypesOf(Any::class.java) (that parameter itself stands for excludeObjectClass). Looking at the bytecode of Kotlin classes you immediately see, that they are actually looking the same as Java classes. There is no Any-superclass there. Note that Kotlins Any is actually also in other means very similar to Javas Object (but not the same, check also the following answer to 'does Any == Object'). So, we need to include the Object-class when scanning for subtypes of Any (i.e. excludeObjectClass=false).
Another problem could be the setup of your URL array. I just used the following to setup the reflections util:
val reflections = Reflections(ConfigurationBuilder()
.addUrls(ClasspathHelper.forPackage("my.test.package"))
.setScanners(TypeAnnotationsScanner(), SubTypesScanner(false)))
which will resolve all matching subtypes and will return subtypes also for Any.
reflections.getSubTypesOf(MyCustomSuperType::class.java).forEach(::println)
reflections.getSubTypesOf(Any::class.java).forEach(::println)
Analysing further: you mention "Kotlin class source files"... if that means you are pointing to the directory containing the .kt-files, then that is probably your problem. Try to use the directory which contains the .class-files instead. Moreover, ensure that the classes are on the classpath.
Maybe you know already, maybe not? Note also that if you have a (classes) directory, say /sample/directory, which is on the classpath and which contains a package, say org.example (which corresponds to the folder structure org/example or full path /sample/directory/org/example) then you must ensure that you add an URL similar to the following:
YourClass::class.java.classLoader.getResource("")
and not:
YourClass::class.java.classLoader.getResource("org.example")
// nor:
YourClass::class.java.classLoader.getResource("org/example")
You basically require the "base" directory (in the example /sample/directory or from the view of the classloader just "")) where to lookup the packages and not the package itself. If you would supply one of the latter URLs, only classes that are in the default package (within /sample/directory/org/example) would actually be found, which however is a rather uncommon setup.
Preface: in ez4 i remember there was a tpl function to read ini settings, we used to use this to pass specific locations or id's with which we could then render certain content.
In ezplatform I am now doing the same thing but by using the PreContentViewListener (in the PreContentViewListener read a yml file and pass into the view as params), but this doesn't feel like the correct way as the PreContentViewListener doesn't always get triggered, in custom controllers for example.
Question
Is there a native way to read yaml files from within twig templates? After searching the docs and available packagists i cannot find anything :/
If your needs are simple (i.e. reading container parameters), you can also use eZ Publish config resolver component which is available in any Twig template with ezpublish.configResolver.
You can specify a siteaccess aware parameter in format <namespace>.<scope>.<param_name>, like this:
parameters:
app.default.param.name: 'Default param value'
app.eng.param.name: 'English param value'
app.cro.param.name: 'Croatian param value'
where default, eng and cro are different eZ Publish scopes.
You can then use the config resolver to fetch the parameter in current scope with:
{{ ezpublish.configResolver.parameter('param.name', 'app') }}
If you have Legacy Bridge installed, this even falls back to legacy INI settings if no Symfony container parameter exists:
{{ ezpublish.configResolver.parameter('SiteSettings.SiteName', 'site') }}
Disclaimer: Some say that using config resolver is bad practice, but for simpler usecases it is okay, IMO.
Have a look to our CjwPublishToolsBundle.
https://github.com/cjw-network/CjwPublishToolsBundle
https://github.com/cjw-network/CjwPublishToolsBundle/blob/master/Services/TwigConfigFunctionsService.php
Here we have 2 wrapper twig functions
{{cjw_config_resolver_get_parameter ( 'yamlvariablename', 'namespace default ezsettings') }}
=> ezpublish siteaccessmatching
{{cjw_config_get_parameter( 'mailer_transport' )}}
=> core symfony yaml reader without siteaccess
You could do a lot of things in eZ 4 and not always really good for your application design. ezini was able to read the configuration from the template but now in eZ Platform and by extension Symfony you need to respect more common patterns. IMO the view should not be that smart.
Then injecting variables to the view from a listener (PreContentViewListener or your own) is not a bad idea.
You can also use the Twig Globals that could allow you to do 2 global things:
inject variables (1)
inject a service (2)
Look here: https://symfony.com/doc/current/templating/global_variables.html
(2): please don't inject the service container globally it is bad
(1): I don't remember if the Twig Globals are Site Access aware, if not injecting your own service (2) to manage access to the config might be better.
And finally, I think that the use case is not a common one:
we used to use this to pass specific locations or id's with which we could then render certain content.
Most of the time it is a bad idea to pass ids coming from the configuration to render something, it is much better to organize the content structure to let you pull the location you want using the PHP API. (no id in configuration no hassle with dev, stage, preprod and prod architecture)
I'm using Flow to help author a JS project. If I want to provide a libdef file to supplement it do I need to create it manually, or am I able to execute some magic command that I'm not aware of yet which will generate the lib def for me?
Something like $ flow-typed doyourmagic would be nice.
EDIT:
Found this https://stackoverflow.com/a/38906578/192999
Which says:
There's two things:
If the file is owned by you (i.e. not a third party lib inside node_modules or such), then you can create a *.js.flow file next to it that documents its exports.
If the file is not owned by you (i.e. third party lib inside node_modules or such), then you can create a libdef file inside flow-typed/name-of-library.js
For .js.flow files
you write the definitions like this:
// #flow
declare module.exports: { ... }
For libdef files you write the definitions like this:
declare module "my-third-party-library" { declare module.exports: {... } }
For my question I fall into the "is owned by you" camp.
I guess I'm confused as to:
How I write these files.
How/where I publish these files to package it up for another project to reference.
Also, why do I need to create the .js.flow file manually? Can this not be magically generated? Perhaps that's the intention going forward but not implemented yet.
I found a nice guide showing how to package flow code together with the compiled code. So:
You do not have to write your own libdefs, you can use the entire flow source code. If you want a definition with only the type declarations, you can look into flow gen-flow-files, although that is still experimental and might fail.
You can package them as *.js.flow and the flow checker will automatically pick those up when you import your library.
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In my endless quest in over-complicating simple stuff, I am researching the most 'Pythonic' way to provide global configuration variables inside the typical 'config.py' found in Python egg packages.
The traditional way (aah, good ol' #define!) is as follows:
MYSQL_PORT = 3306
MYSQL_DATABASE = 'mydb'
MYSQL_DATABASE_TABLES = ['tb_users', 'tb_groups']
Therefore global variables are imported in one of the following ways:
from config import *
dbname = MYSQL_DATABASE
for table in MYSQL_DATABASE_TABLES:
print table
or:
import config
dbname = config.MYSQL_DATABASE
assert(isinstance(config.MYSQL_PORT, int))
It makes sense, but sometimes can be a little messy, especially when you're trying to remember the names of certain variables. Besides, providing a 'configuration' object, with variables as attributes, might be more flexible. So, taking a lead from bpython config.py file, I came up with:
class Struct(object):
def __init__(self, *args):
self.__header__ = str(args[0]) if args else None
def __repr__(self):
if self.__header__ is None:
return super(Struct, self).__repr__()
return self.__header__
def next(self):
""" Fake iteration functionality.
"""
raise StopIteration
def __iter__(self):
""" Fake iteration functionality.
We skip magic attribues and Structs, and return the rest.
"""
ks = self.__dict__.keys()
for k in ks:
if not k.startswith('__') and not isinstance(k, Struct):
yield getattr(self, k)
def __len__(self):
""" Don't count magic attributes or Structs.
"""
ks = self.__dict__.keys()
return len([k for k in ks if not k.startswith('__')\
and not isinstance(k, Struct)])
and a 'config.py' that imports the class and reads as follows:
from _config import Struct as Section
mysql = Section("MySQL specific configuration")
mysql.user = 'root'
mysql.pass = 'secret'
mysql.host = 'localhost'
mysql.port = 3306
mysql.database = 'mydb'
mysql.tables = Section("Tables for 'mydb'")
mysql.tables.users = 'tb_users'
mysql.tables.groups = 'tb_groups'
and is used in this way:
from sqlalchemy import MetaData, Table
import config as CONFIG
assert(isinstance(CONFIG.mysql.port, int))
mdata = MetaData(
"mysql://%s:%s#%s:%d/%s" % (
CONFIG.mysql.user,
CONFIG.mysql.pass,
CONFIG.mysql.host,
CONFIG.mysql.port,
CONFIG.mysql.database,
)
)
tables = []
for name in CONFIG.mysql.tables:
tables.append(Table(name, mdata, autoload=True))
Which seems a more readable, expressive and flexible way of storing and fetching global variables inside a package.
Lamest idea ever? What is the best practice for coping with these situations? What is your way of storing and fetching global names and variables inside your package?
How about just using the built-in types like this:
config = {
"mysql": {
"user": "root",
"pass": "secret",
"tables": {
"users": "tb_users"
}
# etc
}
}
You'd access the values as follows:
config["mysql"]["tables"]["users"]
If you are willing to sacrifice the potential to compute expressions inside your config tree, you could use YAML and end up with a more readable config file like this:
mysql:
- user: root
- pass: secret
- tables:
- users: tb_users
and use a library like PyYAML to conventiently parse and access the config file
I like this solution for small applications:
class App:
__conf = {
"username": "",
"password": "",
"MYSQL_PORT": 3306,
"MYSQL_DATABASE": 'mydb',
"MYSQL_DATABASE_TABLES": ['tb_users', 'tb_groups']
}
__setters = ["username", "password"]
#staticmethod
def config(name):
return App.__conf[name]
#staticmethod
def set(name, value):
if name in App.__setters:
App.__conf[name] = value
else:
raise NameError("Name not accepted in set() method")
And then usage is:
if __name__ == "__main__":
# from config import App
App.config("MYSQL_PORT") # return 3306
App.set("username", "hi") # set new username value
App.config("username") # return "hi"
App.set("MYSQL_PORT", "abc") # this raises NameError
.. you should like it because:
uses class variables (no object to pass around/ no singleton required),
uses encapsulated built-in types and looks like (is) a method call on App,
has control over individual config immutability, mutable globals are the worst kind of globals.
promotes conventional and well named access / readability in your source code
is a simple class but enforces structured access, an alternative is to use #property, but that requires more variable handling code per item and is object-based.
requires minimal changes to add new config items and set its mutability.
--Edit--:
For large applications, storing values in a YAML (i.e. properties) file and reading that in as immutable data is a better approach (i.e. blubb/ohaal's answer).
For small applications, this solution above is simpler.
How about using classes?
# config.py
class MYSQL:
PORT = 3306
DATABASE = 'mydb'
DATABASE_TABLES = ['tb_users', 'tb_groups']
# main.py
from config import MYSQL
print(MYSQL.PORT) # 3306
Let's be honest, we should probably consider using a Python Software Foundation maintained library:
https://docs.python.org/3/library/configparser.html
Config example: (ini format, but JSON available)
[DEFAULT]
ServerAliveInterval = 45
Compression = yes
CompressionLevel = 9
ForwardX11 = yes
[bitbucket.org]
User = hg
[topsecret.server.com]
Port = 50022
ForwardX11 = no
Code example:
>>> import configparser
>>> config = configparser.ConfigParser()
>>> config.read('example.ini')
>>> config['DEFAULT']['Compression']
'yes'
>>> config['DEFAULT'].getboolean('MyCompression', fallback=True) # get_or_else
Making it globally-accessible:
import configpaser
class App:
__conf = None
#staticmethod
def config():
if App.__conf is None: # Read only once, lazy.
App.__conf = configparser.ConfigParser()
App.__conf.read('example.ini')
return App.__conf
if __name__ == '__main__':
App.config()['DEFAULT']['MYSQL_PORT']
# or, better:
App.config().get(section='DEFAULT', option='MYSQL_PORT', fallback=3306)
....
Downsides:
Uncontrolled global mutable state.
A small variation on Husky's idea that I use. Make a file called 'globals' (or whatever you like) and then define multiple classes in it, as such:
#globals.py
class dbinfo : # for database globals
username = 'abcd'
password = 'xyz'
class runtime :
debug = False
output = 'stdio'
Then, if you have two code files c1.py and c2.py, both can have at the top
import globals as gl
Now all code can access and set values, as such:
gl.runtime.debug = False
print(gl.dbinfo.username)
People forget classes exist, even if no object is ever instantiated that is a member of that class. And variables in a class that aren't preceded by 'self.' are shared across all instances of the class, even if there are none. Once 'debug' is changed by any code, all other code sees the change.
By importing it as gl, you can have multiple such files and variables that lets you access and set values across code files, functions, etc., but with no danger of namespace collision.
This lacks some of the clever error checking of other approaches, but is simple and easy to follow.
Similar to blubb's answer. I suggest building them with lambda functions to reduce code. Like this:
User = lambda passwd, hair, name: {'password':passwd, 'hair':hair, 'name':name}
#Col Username Password Hair Color Real Name
config = {'st3v3' : User('password', 'blonde', 'Steve Booker'),
'blubb' : User('12345678', 'black', 'Bubb Ohaal'),
'suprM' : User('kryptonite', 'black', 'Clark Kent'),
#...
}
#...
config['st3v3']['password'] #> password
config['blubb']['hair'] #> black
This does smell like you may want to make a class, though.
Or, as MarkM noted, you could use namedtuple
from collections import namedtuple
#...
User = namedtuple('User', ['password', 'hair', 'name']}
#Col Username Password Hair Color Real Name
config = {'st3v3' : User('password', 'blonde', 'Steve Booker'),
'blubb' : User('12345678', 'black', 'Bubb Ohaal'),
'suprM' : User('kryptonite', 'black', 'Clark Kent'),
#...
}
#...
config['st3v3'].password #> passwd
config['blubb'].hair #> black
I did that once. Ultimately I found my simplified basicconfig.py adequate for my needs. You can pass in a namespace with other objects for it to reference if you need to. You can also pass in additional defaults from your code. It also maps attribute and mapping style syntax to the same configuration object.
please check out the IPython configuration system, implemented via traitlets for the type enforcement you are doing manually.
Cut and pasted here to comply with SO guidelines for not just dropping links as the content of links changes over time.
traitlets documentation
Here are the main requirements we wanted our configuration system to have:
Support for hierarchical configuration information.
Full integration with command line option parsers. Often, you want to read a configuration file, but then override some of the values with command line options. Our configuration system automates this process and allows each command line option to be linked to a particular attribute in the configuration hierarchy that it will override.
Configuration files that are themselves valid Python code. This accomplishes many things. First, it becomes possible to put logic in your configuration files that sets attributes based on your operating system, network setup, Python version, etc. Second, Python has a super simple syntax for accessing hierarchical data structures, namely regular attribute access (Foo.Bar.Bam.name). Third, using Python makes it easy for users to import configuration attributes from one configuration file to another.
Fourth, even though Python is dynamically typed, it does have types that can be checked at runtime. Thus, a 1 in a config file is the integer ‘1’, while a '1' is a string.
A fully automated method for getting the configuration information to the classes that need it at runtime. Writing code that walks a configuration hierarchy to extract a particular attribute is painful. When you have complex configuration information with hundreds of attributes, this makes you want to cry.
Type checking and validation that doesn’t require the entire configuration hierarchy to be specified statically before runtime. Python is a very dynamic language and you don’t always know everything that needs to be configured when a program starts.
To acheive this they basically define 3 object classes and their relations to each other:
1) Configuration - basically a ChainMap / basic dict with some enhancements for merging.
2) Configurable - base class to subclass all things you'd wish to configure.
3) Application - object that is instantiated to perform a specific application function, or your main application for single purpose software.
In their words:
Application: Application
An application is a process that does a specific job. The most obvious application is the ipython command line program. Each application reads one or more configuration files and a single set of command line options and then produces a master configuration object for the application. This configuration object is then passed to the configurable objects that the application creates. These configurable objects implement the actual logic of the application and know how to configure themselves given the configuration object.
Applications always have a log attribute that is a configured Logger. This allows centralized logging configuration per-application.
Configurable: Configurable
A configurable is a regular Python class that serves as a base class for all main classes in an application. The Configurable base class is lightweight and only does one things.
This Configurable is a subclass of HasTraits that knows how to configure itself. Class level traits with the metadata config=True become values that can be configured from the command line and configuration files.
Developers create Configurable subclasses that implement all of the logic in the application. Each of these subclasses has its own configuration information that controls how instances are created.