Develop Reference

Python flask server to retrieve certain records

I have this following python code for a Flask server. I am trying to have this part of the code list all my vehicles that match the horsepower that I put in through my browser. I want it to return all the car names that match the horsepower, but what I have doesn't seem to be working? It returns nothing. I know the issue is somewhere in the "for" statement, but I don't know how to fix it.
This is my first time doing something like this and I've been trying multiple things for hours. I can't figure it out. Could you please help?
from flask import Flask
from flask import request
import os, json
app = Flask(__name__, static_folder='flask')
#app.route('/HORSEPOWER')
def horsepower():
horsepower = request.args.get('horsepower')
message = "<h3>HORSEPOWER "+str(horsepower)+"</h3>"
path = os.getcwd() + "/data/vehicles.json"
with open(path) as f:
data = json.load(f)
for record in data:
horsepower=int(record["Horsepower"])
if horsepower == record:
car=record["Car"]
return message

The following example should meet your expectations.
from flask import Flask
from flask import request
import os, json
app = Flask(__name__)
#app.route('/horsepower')
def horsepower():
# The type of the URL parameters are automatically converted to integer.
horsepower = request.args.get('horsepower', type=int)
# Read the file which is located in the data folder relative to the
# application root directory.
path = os.path.join(app.root_path, 'data', 'vehicles.json')
with open(path) as f:
data = json.load(f)
# A list of names of the data sets is created,
# the performance of which corresponds to the parameter passed.
cars = [record['Car'] for record in data if horsepower == int(record["Horsepower"])]
# The result is then output separated by commas.
return f'''
<h3>HORSEPOWER {horsepower}</h3>
<p>{','.join(cars)}<p>
'''
There are many different ways of writing the loop. I used a short variant in the example. In more detail, you can use these as well.
cars = []
for record in data:
if horsepower == int(record['Horsepower']):
cars.append(record['Car'])
As a tip:
Pay attention to when you overwrite the value of a variable by using the same name.

Process an input Excel file and serialize its rows

I have to solve an exercise, but I can't solve one error.
I don't have so much knowledge about Boo language, sorry.
My code is:
public class Item (IIDataReaderLoadable):
Sequence as long
Code as string
Description as string
Weight as decimal
Id as Guid
def LoadFromReader(reader as IDataReader):
Sequence = long.Parse(reader[0].ToString());
Code = reader[1].ToString();
Weight = decimal.Parse(reader[2].ToString());
Description = reader[3].ToString();
Id = Guid.Parse(reader[4].ToString());
TableName as string:
get:
return "Hoja1$"
operation read_MasterData_etlexcel:
log = ProcessContext.GetLogger()
file = ProcessContext.InputFile
log.Info("Reading $file")
for Data in EntityReader[of Item].Read(file):
yield Row.FromObject(Data)
operation print_etlexcel:
log = ProcessContext.GetLogger()
for row in rows:
log.Info(row.ToString())
yield row
def serialize_row(it as Object, id as Guid):
serializer = XmlSerializer(typeof(Item))
writer = FileStream("output" + id.ToString() +".xml", FileMode.Create);
serializer.Serialize(writer, it);
writer.Close();
serialize_row(Item, Item.Id)
process process_owners_etlexcel:
read_MasterData_etlexcel()
print_etlexcel()
When I execute it in a command window I get the next error:
2018-05-14 14:18:44.0479 [Error] [Mss.Etl.DSLLoader.EtlSetup] Cannot execute ./e
xcelfile/import.boo BCE0000: C:\Program Files\Mecalux\GnaService2015\excelfile\i
mport.boo(57,30): BCE0020: Boo.Lang.Compiler.CompilerError: An instance of type
'Mss.Item' is required to access non static member 'Id'.
I want to read an Excel file that contains some columns and I have to créate a boo script that recover the content of my Excel file, then I have to map each row from the Excel file into an object of you my class Ítem, and serialize the object in a XML file
Thanks

The bug is on this line:
serialize_row(Item, Item.Id)
The Item.Id field is a member field not a static field, which means you need an instance. It looks like you're calling it there as as a static so its blowing up. I'm not sure what the solution is because you have a couple of macros there that are not defined in the code example so I'm not sure what they're doing but I would think you either need to remove that line or pass in a member id or a random one.
I would have to guess this is the solution:
item = Item()
serialize_row(item, item.Id)

How to create random entries in database with python

I need to create random entries with a given sql-schema in sql with the help of python programming language.
Is there a simple way to do that or do I have to write own generators?

You could use Wikipedia as a data source. Select categories that are relevant to your schema and pick random articles from those categories.
This code accesses CatScan using requests for convenience. Maybe there is a library that can do the same (return pages in a Wikipedia category), but writing this short piece of code was easier than finding one.
choice selects a random element from a list.
from random import choice
from requests import post
def title(page):
return page['a']['title'].split('(')[0].replace('_', ' ').strip()
def category(name, depth=0):
url = 'https://tools.wmflabs.org/catscan2/catscan2.php'
payload = {
'categories': name,
'depth': depth,
'format': 'json',
'doit': 'Do it!',
}
category = post(url, data=payload).json()['*'][0]['a']['*']
return [title(page) for page in category]
first = category('Italian masculine given names')
last = category('Surnames of Italian origin')
work = category('Organized crime members by role')
for i in range(10):
print(*map(choice, (first, last, work)), sep=',')
The result:
$ python random_data.py | column -t -s,
Santino Comolli Boss
Constantino Furlan Made man
Ernesto Forlán Consigliere
Silvestro Gherardi Informant
Adelmo Mancuso Bagman
Giuliano Paganelli Made man
Renato Barberis Capobastone
Roberto Comollo Consigliere
Dario Speroni Consigliere
Gastone Pestalozzi Underboss

You could try a recently launched Python package called pydbgen.
Here is a article about it.
Introducing pydbgen: A random dataframe/database table generator
For example, this generate a .DB file which can be used with MySQL or SQLite. The resulting database table was opened in DB Browser for SQLite and looks like following,
myDB.gen_table(db_file='Testdb.DB',table_name='People',
fields=['name','city','street_address','email'])
As you can see, the db file name, the table name, and the fields can be specified.

You can also use faker.
just pip install faker
Just go through documentation and check it out

Store a list of dictionaries in GAE

I have a list of about 20 objects and for each object I return a list of 10 dictionaries.
I am trying to store the list of 10 dictionaries for each object in the list on GAE; I do not think I am writing the code correctly to store this information to GAE.
Here is what I have:
Before my main request handler I have this class:
class Tw(db.Model):
tags = db.ListProperty()
ip = db.StringProperty()
In my main request handler I have the following:
for city in lst_of_cities: # this is the list of 20 objects
dict_info = hw12.twitter(city) # this is the function to get the list of 10 dictionaries for each object in the list
datastore = Tw() # this is the class defined for db.model
datastore.tags.append(dict_info) #
datastore.ip = self.request.remote_addr
datastore.put()
data = Data.gql("") #data entities we need to fetch
I am not sure if this code is write at all. If anyone could please help it would be much appreciated.

Welcome to Stack Overflow!
I see a few issues:
Dictionaries are not supported value types for App Engine properties.
You're only storing the last entity; the rest are discarded.
You're using a ListProperty, but instead of appending each element of dict_info, you're doing a single append of the entire list.
Since you can't store a raw dictionary inside a property, you need to serialize it to some other format, like JSON or pickle. Here's a revised example using pickle:
from google.appengine.ext import db
import pickle
class Tw(db.Model):
tags = db.BlobProperty()
ip = db.StringProperty()
entities = []
for city in lst_of_cities:
dict_info = hw12.twitter(city)
entity = Tw()
entity.tags = db.Blob(pickle.dumps(dict_info))
entity.ip = self.request.remote_addr
entities.append(entity)
db.put(entities)
When you fetch the entity later, you can retrieve your list of dictionaries with pickle.loads(entity.tags).

When I deal with data types that are not directly supported by Google App Engine like dictionaries or custom data type, I usually adopt the handy PickleProperty.
from google.appengine.ext import db
import pickle
class PickleProperty(db.Property):
def get_value_for_datastore(self, model_instance):
value = getattr(model_instance, self.name, None)
return pickle.dumps(value)
def make_value_from_datastore(self, value):
return pickle.loads(value)
Once declared the PickleProperty class in your commons.py module, you can use it to store your custom data with something like this:
from google.appengine.ext import db
from commons import PickleProperty
class Tw(db.Model):
tags = PickleProperty()
ip = db.StringProperty()
entities = []
for city in lst_of_cities:
dict_info = hw12.twitter(city)
entity = Tw()
entity.tags = dict_info
entity.ip = self.request.remote_addr
entities.append(entity)
db.put(entities)
To retrieve the data back go with:
entity.tags

Since this was written, the App Engine has pushed out their experimental "ndb" Python database model, which contains in particular the JsonProperty, something that pretty well directly implements what you want.
Now, you need to be running the Python 2.7 version of the App Engine, which is still not quite ready for production, but it all seems pretty stable these days, GvR himself seems to be writing a lot of the code which bodes well for the code quality, and I'm intending to use this in production sometime this year...

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.