Develop Reference

How do I configure multiple dictionary keys in a yaml file in Python?

I am trying to use a yaml file to store dictionary keys so I can parse various json payloads.
I have the following yaml file loaded into a variable called 'cfg':
my_table: metadata
When I run:
for i in json['resources']:
print(i[cfg['my_table']])
I can see all values from my json's ['metadata'] keys just fine.
However, I would like to see all values from the ['metadata']['guid'] keys that exist under ['resources']. So when I change my yaml file to:
my_table: metadata, guid
It doesn't work. I've also tried these variations:
my_table: ['metadata', 'guid'] #tried ''.join("['{0}']".format(a) for a in cfg['my_table']) which gives me what I want, but when I shove this inside i[], I get a key error
my_table: ['metadata']['guid'] #yaml file doesn't parse properly
Any ideas?

So you want to store dictionary keys in a yaml file?
Just do
# keys.yaml
my_table: [metadata, guid]
And then in your python file
keys = yaml.safe_load('keys.yaml')['my_table']
for obj in json['resources']: # don't call it json, that's a package name
print(obj[keys[0]][keys[1]])
For a variable number of keys (not only two) do it like so:
def recursive_getitem(obj, keys):
if len(keys) == 0:
return obj
return recursive_getitem(obj[keys[0]], keys[1:])
and then do
for obj in json['resources']:
print(recursive_getitem(obj, keys))
To answer your second question in the comments, you need to use a nested list
# keys.yaml
my_table:
- [metadata, guid]
- [entity, name]
.
# py file
keys = yaml.safe_load('keys.yaml')['my_table']
for obj in json['resources']: # don't call it json, that's a package name
print(obj[keys[0][0]][keys[0][1]])
print(obj[keys[1][0]][keys[1][1]])

Python- how can I set the value for params from another file

I am new to Python. I have to edit some test I have.
I have a file which inclused all the details for a test I have to execute. The file name for example is "test 1"
In this file there are few global params:
LINK_IP_ADDR = "10.8.22.89"
STABILITY_SLEEP = 5
MAIN_STATE_SLEEP = 30
For making the tests automaticly and generic I want to set the the value from the params from another python file (for example config_file). How should I do it?

You should probably use configuration files for this. The ConfigParser package would do the job.
If you want a quick and dirty version, the following could be for you.
In your 'test files', write the following:
class Params:
LINK_IP_ADDR = "10.8.22.89"
STABILITY_SLEEP = 5
MAIN_STATE_SLEEP = 30
Then in your main program you import the parameters you want and just use them:
from test1 import Params
# from test2 import Params
print Params.LINK_IP_ADDR
You can then switch your import statements to the file you want to use. I would use a normal .ini file with different sections though.

Here is a quick n' dirty way from a plain file:
params = dict()
with open('config_file') as f:
for line in f:
param, value = line.split("=")
params[param.strip()] = value.strip()
print(params)
config_file:
LINK_IP_ADDR = "10.8.22.89"
STABILITY_SLEEP = 5
MAIN_STATE_SLEEP = 30

for config file i used .yaml file. This format stores your config like json or python-dict. U can store complex structure (array, hashmap, ...) very good
config.yaml
LINK_IP_ADDR: 10.8.22.89
STABILITY_SLEEP: 5
MAIN_STATE_SLEEP: 30
another.py
import yaml
configs = yaml.safe_load(file("path_to_config.yaml"))
# to use you configs:
configs['LINK_IP_ADDR']
#.....

Python argparser. List of dict in INI

I have a following list in my python module:
couples = [("somekey1", "somevalue1"), ("somekey2", "somevalue2"), ("somekey3", "somevalue3"),....]
I am storing configurations for my app in "configs.ini" and i use configparser tor read it.
I checked documentation for configparser and didn't find how can i read my list from file.
UPD:
Does anybody know how i can read following list from my configs or maybe exists another way to store it in file ?
UPD2: it is list of logins and password.May it can help.

I'm not sure I understand this correctly but if you want to create a config file to easily read a list like you've shown then create a section in your configs.ini
[section]
key = value
key2 = value2
key3 = value3
and then
>> config = ConfigParser.RawConfigParser()
>> config.read('configs.ini')
>> items = config.items('section')
>> items
[('key', 'value'), ('key2', 'value2'), ('key3', 'value3')]
which is basically what you say you need.
If on the other hand what you are saying is that your config file contains:
[section]
couples = [("somekey1", "somevalue1"), ("somekey2", "somevalue2"), ("somekey3", "somevalue3")]
what you could do is extend the config parser like for example so:
class MyConfigParser(ConfigParser.RawConfigParser):
def get_list_of_tups(self, section, option):
value = self.get(section, option)
import re
couples = re.finditer('\("([a-z0-9]*)", "([a-z0-9]*)"\)', value)
return [(c.group(1), c.group(2)) for c in couples]
and then your new parser can get fetch your list for you:
>> my_config = MyConfigParser()
>> my_config.read('example.cfg')
>> couples = my_config.get_list_of_tups('section', 'couples')
>> couples
[('somekey1', 'somevalue1'), ('somekey2', 'somevalue2'), ('somekey3', 'somevalue3')]
The second situation is just making things hard for yourself I think.

You can use the pickle module to dump and load your list to a file.
To dump your list:
import pickle
couples = [("somekey1", "somevalue1"), ("somekey2", "somevalue2"), ("somekey3", "somevalue3"),....]
pickle.dump(couples, open("save.p", "wb"))
To load your list:
couples = pickle.load(open("save.p", "rb"))

What you're looking for is probably the configparser module. Check out these links for more details:
1) How to read and write INI file with Python3?
2) http://docs.python.org/2.7/library/configparser.html#examples

Split "dict" definition up between files

I'd like to define the contents of a large dictionary object up between files. I'm wondering if this is possible in python.
Ideally, this is what I'd like to do:
Main File: (dict_object_main.py)
# File name: dict_object_main.py
import dict_object_sub1
import dict_object_sub2
dict_object = {}
def doSomeStuffWithTheDictObject:
...
return
1st File that adds a lot of stuff to "dict_object": (dict_object_sub1.py)
# File name: dict_object_sub1.py
from dict_object_main import dict_object
dict_object['sub1'] ={
'property1':'value1'
...
,'property9999':'value9999'
}
2nd File that adds a lot of stuff to "dict_object": (dict_object_sub2.py)
# File name: dict_object_sub2.py
from dict_object_main import dict_object
dict_object['sub2'] ={
'property1':'value1'
...
,'property9999':'value9999'
}
I have something similar set up in javascript. Is it ok to do it this way in Python or should I be doing it differently?
Thanks!

Edit: The first part to my previous answer was wrong. The lesson I learned is don't have circular dependencies. The following is correct:
Another option is to try this in the main file:
from dict_object_sub1 import dict_object_sub1
from dict_object_sub2 import dict_object_sub2
dict_object = {}
dict_object.update(dict_object_sub1)
dict_object.update(dict_object_sub2)
Then in both of the sub files do something like this:
# dict_object_sub1.py
dict_object_sub1 = {...}

You may want to use the update method instead.
# Same for dict_object_sub1.py or dict_object_sub2.py
from dict_object_main import dict_object
dict_object.update({
'prop1': 'val1',
# ...
})
Note:
I don't think it makes much sense to split the declaration out on two different files. The final memory occupied by the dictionary will be exactly the same in both cases.
Edit:
As daveydave400 pointed out in his answer, the importing order is wrong too.
You need at least 3 distinct files (or doing the updates in the importing module):
A dict_declare.py file, where you declare your dictionary:
dict_object = {}
A file for each partial dictionary declaration:
from dict_object import dict_object
dict_object.update({
'prop1': 'val1',
# ...
})
Your main file:
from dict_declare import dict_object
import dict_object_sub<n>
# ... repeat
def doSomeStuffWithTheDictObject:
...
return

Properties file in python (similar to Java Properties)

Given the following format (.properties or .ini):
propertyName1=propertyValue1
propertyName2=propertyValue2
...
propertyNameN=propertyValueN
For Java there is the Properties class that offers functionality to parse / interact with the above format.
Is there something similar in python's standard library (2.x) ?
If not, what other alternatives do I have ?

I was able to get this to work with ConfigParser, no one showed any examples on how to do this, so here is a simple python reader of a property file and example of the property file. Note that the extension is still .properties, but I had to add a section header similar to what you see in .ini files... a bit of a bastardization, but it works.
The python file: PythonPropertyReader.py
#!/usr/bin/python
import ConfigParser
config = ConfigParser.RawConfigParser()
config.read('ConfigFile.properties')
print config.get('DatabaseSection', 'database.dbname');
The property file: ConfigFile.properties
[DatabaseSection]
database.dbname=unitTest
database.user=root
database.password=
For more functionality, read: https://docs.python.org/2/library/configparser.html

For .ini files there is the configparser module that provides a format compatible with .ini files.
Anyway there's nothing available for parsing complete .properties files, when I have to do that I simply use jython (I'm talking about scripting).

I know that this is a very old question, but I need it just now and I decided to implement my own solution, a pure python solution, that covers most uses cases (not all):
def load_properties(filepath, sep='=', comment_char='#'):
"""
Read the file passed as parameter as a properties file.
"""
props = {}
with open(filepath, "rt") as f:
for line in f:
l = line.strip()
if l and not l.startswith(comment_char):
key_value = l.split(sep)
key = key_value[0].strip()
value = sep.join(key_value[1:]).strip().strip('"')
props[key] = value
return props
You can change the sep to ':' to parse files with format:
key : value
The code parses correctly lines like:
url = "http://my-host.com"
name = Paul = Pablo
# This comment line will be ignored
You'll get a dict with:
{"url": "http://my-host.com", "name": "Paul = Pablo" }

A java properties file is often valid python code as well. You could rename your myconfig.properties file to myconfig.py. Then just import your file, like this
import myconfig
and access the properties directly
print myconfig.propertyName1

if you don't have multi line properties and a very simple need, a few lines of code can solve it for you:
File t.properties:
a=b
c=d
e=f
Python code:
with open("t.properties") as f:
l = [line.split("=") for line in f.readlines()]
d = {key.strip(): value.strip() for key, value in l}

If you have an option of file formats I suggest using .ini and Python's ConfigParser as mentioned. If you need compatibility with Java .properties files I have written a library for it called jprops. We were using pyjavaproperties, but after encountering various limitations I ended up implementing my own. It has full support for the .properties format, including unicode support and better support for escape sequences. Jprops can also parse any file-like object while pyjavaproperties only works with real files on disk.

This is not exactly properties but Python does have a nice library for parsing configuration files. Also see this recipe: A python replacement for java.util.Properties.

i have used this, this library is very useful
from pyjavaproperties import Properties
p = Properties()
p.load(open('test.properties'))
p.list()
print(p)
print(p.items())
print(p['name3'])
p['name3'] = 'changed = value'

Here is link to my project: https://sourceforge.net/projects/pyproperties/. It is a library with methods for working with *.properties files for Python 3.x.
But it is not based on java.util.Properties

This is a one-to-one replacement of java.util.Propeties
From the doc:
def __parse(self, lines):
""" Parse a list of lines and create
an internal property dictionary """
# Every line in the file must consist of either a comment
# or a key-value pair. A key-value pair is a line consisting
# of a key which is a combination of non-white space characters
# The separator character between key-value pairs is a '=',
# ':' or a whitespace character not including the newline.
# If the '=' or ':' characters are found, in the line, even
# keys containing whitespace chars are allowed.
# A line with only a key according to the rules above is also
# fine. In such case, the value is considered as the empty string.
# In order to include characters '=' or ':' in a key or value,
# they have to be properly escaped using the backslash character.
# Some examples of valid key-value pairs:
#
# key value
# key=value
# key:value
# key value1,value2,value3
# key value1,value2,value3 \
# value4, value5
# key
# This key= this value
# key = value1 value2 value3
# Any line that starts with a '#' is considerered a comment
# and skipped. Also any trailing or preceding whitespaces
# are removed from the key/value.
# This is a line parser. It parses the
# contents like by line.

You can use a file-like object in ConfigParser.RawConfigParser.readfp defined here -> https://docs.python.org/2/library/configparser.html#ConfigParser.RawConfigParser.readfp
Define a class that overrides readline that adds a section name before the actual contents of your properties file.
I've packaged it into the class that returns a dict of all the properties defined.
import ConfigParser
class PropertiesReader(object):
def __init__(self, properties_file_name):
self.name = properties_file_name
self.main_section = 'main'
# Add dummy section on top
self.lines = [ '[%s]\n' % self.main_section ]
with open(properties_file_name) as f:
self.lines.extend(f.readlines())
# This makes sure that iterator in readfp stops
self.lines.append('')
def readline(self):
return self.lines.pop(0)
def read_properties(self):
config = ConfigParser.RawConfigParser()
# Without next line the property names will be lowercased
config.optionxform = str
config.readfp(self)
return dict(config.items(self.main_section))
if __name__ == '__main__':
print PropertiesReader('/path/to/file.properties').read_properties()

If you need to read all values from a section in properties file in a simple manner:
Your config.properties file layout :
[SECTION_NAME]
key1 = value1
key2 = value2
You code:
import configparser
config = configparser.RawConfigParser()
config.read('path_to_config.properties file')
details_dict = dict(config.items('SECTION_NAME'))
This will give you a dictionary where keys are same as in config file and their corresponding values.
details_dict is :
{'key1':'value1', 'key2':'value2'}
Now to get key1's value :
details_dict['key1']
Putting it all in a method which reads that section from config file only once(the first time the method is called during a program run).
def get_config_dict():
if not hasattr(get_config_dict, 'config_dict'):
get_config_dict.config_dict = dict(config.items('SECTION_NAME'))
return get_config_dict.config_dict
Now call the above function and get the required key's value :
config_details = get_config_dict()
key_1_value = config_details['key1']
-------------------------------------------------------------
Extending the approach mentioned above, reading section by section automatically and then accessing by section name followed by key name.
def get_config_section():
if not hasattr(get_config_section, 'section_dict'):
get_config_section.section_dict = dict()
for section in config.sections():
get_config_section.section_dict[section] =
dict(config.items(section))
return get_config_section.section_dict
To access:
config_dict = get_config_section()
port = config_dict['DB']['port']
(here 'DB' is a section name in config file
and 'port' is a key under section 'DB'.)

create a dictionary in your python module and store everything into it and access it, for example:
dict = {
'portalPath' : 'www.xyx.com',
'elementID': 'submit'}
Now to access it you can simply do:
submitButton = driver.find_element_by_id(dict['elementID'])

My Java ini files didn't have section headers and I wanted a dict as a result. So i simply injected an "[ini]" section and let the default config library do its job.
Take a version.ini fie of the eclipse IDE .metadata directory as an example:
#Mon Dec 20 07:35:29 CET 2021
org.eclipse.core.runtime=2
org.eclipse.platform=4.19.0.v20210303-1800
# 'injected' ini section
[ini]
#Mon Dec 20 07:35:29 CET 2021
org.eclipse.core.runtime=2
org.eclipse.platform=4.19.0.v20210303-1800
The result is converted to a dict:
from configparser import ConfigParser
#staticmethod
def readPropertyFile(path):
# https://stackoverflow.com/questions/3595363/properties-file-in-python-similar-to-java-properties
config = ConfigParser()
s_config= open(path, 'r').read()
s_config="[ini]\n%s" % s_config
# https://stackoverflow.com/a/36841741/1497139
config.read_string(s_config)
items=config.items('ini')
itemDict={}
for key,value in items:
itemDict[key]=value
return itemDict

This is what I'm doing in my project: I just create another .py file called properties.py which includes all common variables/properties I used in the project, and in any file need to refer to these variables, put
from properties import *(or anything you need)
Used this method to keep svn peace when I was changing dev locations frequently and some common variables were quite relative to local environment. Works fine for me but not sure this method would be suggested for formal dev environment etc.

import json
f=open('test.json')
x=json.load(f)
f.close()
print(x)
Contents of test.json:
{"host": "127.0.0.1", "user": "jms"}

I have created a python module that is almost similar to the Properties class of Java ( Actually it is like the PropertyPlaceholderConfigurer in spring which lets you use ${variable-reference} to refer to already defined property )
EDIT : You may install this package by running the command(currently tested for python 3).
pip install property
The project is hosted on GitHub
Example : ( Detailed documentation can be found here )
Let's say you have the following properties defined in my_file.properties file
foo = I am awesome
bar = ${chocolate}-bar
chocolate = fudge
Code to load the above properties
from properties.p import Property
prop = Property()
# Simply load it into a dictionary
dic_prop = prop.load_property_files('my_file.properties')

Below 2 lines of code shows how to use Python List Comprehension to load 'java style' property file.
split_properties=[line.split("=") for line in open('/<path_to_property_file>)]
properties={key: value for key,value in split_properties }
Please have a look at below post for details
https://ilearnonlinesite.wordpress.com/2017/07/24/reading-property-file-in-python-using-comprehension-and-generators/

you can use parameter "fromfile_prefix_chars" with argparse to read from config file as below---
temp.py
parser = argparse.ArgumentParser(fromfile_prefix_chars='#')
parser.add_argument('--a')
parser.add_argument('--b')
args = parser.parse_args()
print(args.a)
print(args.b)
config file
--a
hello
--b
hello dear
Run command
python temp.py "#config"

You could use - https://pypi.org/project/property/
eg - my_file.properties
foo = I am awesome
bar = ${chocolate}-bar
chocolate = fudge
long = a very long property that is described in the property file which takes up \
multiple lines can be defined by the escape character as it is done here
url=example.com/api?auth_token=xyz
user_dir=${HOME}/test
unresolved = ${HOME}/files/${id}/${bar}/
fname_template = /opt/myapp/{arch}/ext/{objid}.dat
Code
from properties.p import Property
## set use_env to evaluate properties from shell / os environment
prop = Property(use_env = True)
dic_prop = prop.load_property_files('my_file.properties')
## Read multiple files
## dic_prop = prop.load_property_files('file1', 'file2')
print(dic_prop)
# Output
# {'foo': 'I am awesome', 'bar': 'fudge-bar', 'chocolate': 'fudge',
# 'long': 'a very long property that is described in the property file which takes up multiple lines
# can be defined by the escape character as it is done here', 'url': 'example.com/api?auth_token=xyz',
# 'user_dir': '/home/user/test',
# 'unresolved': '/home/user/files/${id}/fudge-bar/',
# 'fname_template': '/opt/myapp/{arch}/ext/{objid}.dat'}

I did this using ConfigParser as follows. The code assumes that there is a file called config.prop in the same directory where BaseTest is placed:
config.prop
[CredentialSection]
app.name=MyAppName
BaseTest.py:
import unittest
import ConfigParser
class BaseTest(unittest.TestCase):
def setUp(self):
__SECTION = 'CredentialSection'
config = ConfigParser.ConfigParser()
config.readfp(open('config.prop'))
self.__app_name = config.get(__SECTION, 'app.name')
def test1(self):
print self.__app_name % This should print: MyAppName

This is what i had written to parse file and set it as env variables which skips comments and non key value lines added switches to specify
hg:d
-h or --help print usage summary
-c Specify char that identifies comment
-s Separator between key and value in prop file
and specify properties file that needs to be parsed eg : python
EnvParamSet.py -c # -s = env.properties
import pipes
import sys , getopt
import os.path
class Parsing :
def __init__(self , seprator , commentChar , propFile):
self.seprator = seprator
self.commentChar = commentChar
self.propFile = propFile
def parseProp(self):
prop = open(self.propFile,'rU')
for line in prop :
if line.startswith(self.commentChar)==False and line.find(self.seprator) != -1 :
keyValue = line.split(self.seprator)
key = keyValue[0].strip()
value = keyValue[1].strip()
print("export %s=%s" % (str (key),pipes.quote(str(value))))
class EnvParamSet:
def main (argv):
seprator = '='
comment = '#'
if len(argv) is 0:
print "Please Specify properties file to be parsed "
sys.exit()
propFile=argv[-1]
try :
opts, args = getopt.getopt(argv, "hs:c:f:", ["help", "seprator=","comment=", "file="])
except getopt.GetoptError,e:
print str(e)
print " possible arguments -s <key value sperator > -c < comment char > <file> \n Try -h or --help "
sys.exit(2)
if os.path.isfile(args[0])==False:
print "File doesnt exist "
sys.exit()
for opt , arg in opts :
if opt in ("-h" , "--help"):
print " hg:d \n -h or --help print usage summary \n -c Specify char that idetifes comment \n -s Sperator between key and value in prop file \n specify file "
sys.exit()
elif opt in ("-s" , "--seprator"):
seprator = arg
elif opt in ("-c" , "--comment"):
comment = arg
p = Parsing( seprator, comment , propFile)
p.parseProp()
if __name__ == "__main__":
main(sys.argv[1:])

Lightbend has released the Typesafe Config library, which parses properties files and also some JSON-based extensions. Lightbend's library is only for the JVM, but it seems to be widely adopted and there are now ports in many languages, including Python: https://github.com/chimpler/pyhocon

You can use the following function, which is the modified code of #mvallebr. It respects the properties file comments, ignores empty new lines, and allows retrieving a single key value.
def getProperties(propertiesFile ="/home/memin/.config/customMemin/conf.properties", key=''):
"""
Reads a .properties file and returns the key value pairs as dictionary.
if key value is specified, then it will return its value alone.
"""
with open(propertiesFile) as f:
l = [line.strip().split("=") for line in f.readlines() if not line.startswith('#') and line.strip()]
d = {key.strip(): value.strip() for key, value in l}
if key:
return d[key]
else:
return d

this works for me.
from pyjavaproperties import Properties
p = Properties()
p.load(open('test.properties'))
p.list()
print p
print p.items()
print p['name3']

I followed configparser approach and it worked quite well for me. Created one PropertyReader file and used config parser there to ready property to corresponding to each section.
**Used Python 2.7
Content of PropertyReader.py file:
#!/usr/bin/python
import ConfigParser
class PropertyReader:
def readProperty(self, strSection, strKey):
config = ConfigParser.RawConfigParser()
config.read('ConfigFile.properties')
strValue = config.get(strSection,strKey);
print "Value captured for "+strKey+" :"+strValue
return strValue
Content of read schema file:
from PropertyReader import *
class ReadSchema:
print PropertyReader().readProperty('source1_section','source_name1')
print PropertyReader().readProperty('source2_section','sn2_sc1_tb')
Content of .properties file:
[source1_section]
source_name1:module1
sn1_schema:schema1,schema2,schema3
sn1_sc1_tb:employee,department,location
sn1_sc2_tb:student,college,country
[source2_section]
source_name1:module2
sn2_schema:schema4,schema5,schema6
sn2_sc1_tb:employee,department,location
sn2_sc2_tb:student,college,country

You can try the python-dotenv library. This library reads key-value pairs from a .env (so not exactly a .properties file though) file and can set them as environment variables.
Here's a sample usage from the official documentation:
from dotenv import load_dotenv
load_dotenv() # take environment variables from .env.
# Code of your application, which uses environment variables (e.g. from `os.environ` or
# `os.getenv`) as if they came from the actual environment.