Utility Functions

Frappe Framework comes with various utility functions to handle common operations for managing site-specific DateTime management, date and currency formatting, PDF generation, and much more.

These utility methods can be imported from the frappe.utils module (and its nested modules like frappe.utils.logger and frappe.utils.data) in any Python file of your Frappe App. This list is not at all exhaustive, you can take a peek at the Framework codebase to see what's available.

now

now()

Returns the current datetime in the format yyyy-mm-dd hh:mm:ss

from frappe.utils import now

now() # '2021-05-25 06:38:52.242515'

getdate

getdate(string_date=None)

Converts string_date (yyyy-mm-dd) to datetime.date object. If no input is provided, current date is returned. Throws an exception if string_date is an invalid date string.

from frappe.utils import getdate

getdate() # datetime.date(2021, 5, 25)
getdate('2000-03-18') # datetime.date(2000, 3, 18)

today

today()

Returns current date in the format yyyy-mm-dd.

from frappe.utils import today

today() # '2021-05-25'

add\to\date

add_to_date(date, years=0, months=0, weeks=0, days=0, hours=0, minutes=0, seconds=0, as_string=False, as_datetime=False)

`date`: A string representation or `datetime` object, uses the current `datetime` if `None` is passed
`as_string`: Return as string
`as_datetime`: If `as_string` is True and `as_datetime` is also True, returns a `datetime` string otherwise just the `date` string.

This function can be quite handy for doing date/datetime deltas, for instance, adding or substracting certain number of days from a particular date/datetime.

from datetime import datetime # from python std library
from frappe.utils import add_to_date

today = datetime.now().strftime('%Y-%m-%d')
print(today) # '2021-05-21'

after_10_days = add_to_date(datetime.now(), days=10, as_string=True)
print(after_10_days) # '2021-05-31'

add_to_date(datetime.now(), months=2) # datetime.datetime(2021, 7, 21, 15, 31, 18, 119999)
add_to_date(datetime.now(), days=10, as_string=True, as_datetime=True) # '2021-05-31 15:30:23.757661'
add_to_date(None, years=6) # datetime.datetime(2027, 5, 21, 15, 32, 31, 652089)

pretty_date

pretty_date(iso_datetime)

Takes an ISO time and returns a string representing how long ago the date represents. Very common in communication applications like instant messengers.

from frappe.utils import pretty_date, now, add_to_date

pretty_date(now()) # 'just now'

# Some example outputs:

# 1 hour ago
# 20 minutes ago
# 1 week ago
# 5 years ago

format_duration

format_duration(seconds, hide_days=False)

Converts the given duration value in seconds (float) to duration format.

from frappe.utils import format_duration

format_duration(50) # '50s'
format_duration(10000) # '2h 46m 40s'
format_duration(1000000) # '11d 13h 46m 40s'

# Convert days to hours
format_duration(1000000, hide_days=True) # '277h 46m 40s'

comma_and

comma_and(some_list, add_quotes=True)

Given a list or tuple some_list, returns a string of the format 1st item, 2nd item, .... and last item. This function uses frappe._, so you don't have to worry about the translations for the word and. If add_quotes is False, returns the items without quotes, with quotes otherwise. If the type of some_list passed as an argument is something other than a list or tuple, it (some_list) is returned as it is.

from frappe.utils import comma_and

comma_and([1, 2, 3]) # "'1', '2' and '3'"
comma_and(['Apple', 'Ball', 'Cat'], add_quotes=False) # 'Apple, Ball and Cat'
comma_and('abcd') # 'abcd'

There is also a comma_or function which is similar to comma_and except the separator, which is or in the case of comma_or.

money\in\words

money_in_words(number, main_currency=None, fraction_currency=None)

`number`: A floating point money amount
`main_currency`: Uses this as the main currency. If not given, tries to fetch from default settings or uses `INR` if not found there.

This function returns string in words with currency and fraction currency.

from frappe.utils import money_in_words

money_in_words(900) # 'INR Nine Hundred and Fifty Paisa only.'
money_in_words(900.50) # 'INR Nine Hundred and Fifty Paisa only.'
money_in_words(900.50, 'USD') # 'USD Nine Hundred and Fifty Centavo only.'
money_in_words(900.50, 'USD', 'Cents') # 'USD Nine Hundred and Fifty Cents only.'

validate\json\string

validate_json_string(string)

Raises frappe.ValidationError if the given string is a valid JSON (JavaScript Object Notation) string. You can use a try-except block to handle a call to this function as shown the code snippet below.

import frappe
from frappe.utils import validate_json_string

# No Exception thrown
validate_json_string('[]')
validate_json_string('[{}]')
validate_json_string('[{"player": "one", "score": 199}]')

try:
 # Throws frappe.ValidationError
 validate_json_string('invalid json')
except frappe.ValidationError:
 print('Not a valid JSON string')

random_string

random_string(length)

This function generates a random string containing length number of characters. This can be useful for cryptographic or secret generation for some cases.

from frappe.utils import random_string

random_string(40) # 'mcrLCrlvkUdkaOe8m5xMI8IwDB8lszwJsWtZFveQ'
random_string(6) # 'htrB4L'
random_string(6) #'HNRirG'

unique

unique(seq)

seq: An iterable / Sequence

This function returns a list of elements of the given sequence after removing the duplicates. Also, preserves the order, unlike: list(set(seq)).

from frappe.utils import unique

unique([1, 2, 3, 1, 1, 1]) # [1, 2, 3]
unique('abcda') # ['a', 'b', 'c', 'd']
unique(('Apple', 'Apple', 'Banana', 'Apple')) # ['Apple', 'Banana']

get_pdf

get_pdf(html, options=None, output=None)

`html`: HTML string to render
`options`: An optional `dict` for configuration
`output`: A optional `PdfFileWriter` object.

This function uses pdfkit and pyPDF2 modules to generate PDF files from HTML. If output is provided, appends the generated pages to this object and returns it, otherwise returns a byte stream of the PDF.

For instance, generating and returning a PDF as response to a web request:

import frappe
from frappe.utils.pdf import get_pdf

@frappe.whitelist(allow_guest=True)
def generate_invoice():
 cart = [{
 'Samsung Galaxy S20': 10,
 'iPhone 13': 80
 }]

 html = 'Invoice from Star Electronics e-Store!
======================================

'

 # Add items to PDF HTML
 html += ''
 for item, qty in cart.items():
 html += f'2. {item} - {qty}
'
 html += '
'

 # Attaching PDF to response
 frappe.local.response.filename = 'invoice.pdf'
 frappe.local.response.filecontent = get_pdf(html)
 frappe.local.response.type = 'pdf'

get_abbr

get_abbr(string, max_len=2)

Returns an abbrivated (initials only) version of the given string with a maximum of max_len letters. It is extensively used in Frappe Framework and ERPNext to generate thumbnail or placeholder images.

from frappe.utils import get_abbr

get_abbr('Gavin') # 'G'
get_abbr('Coca Cola Company') # 'CC'
get_abbr('Mohammad Hussain Nagaria', max_len=3) # 'MHN'

validate_url

validate_url(txt, throw=False, valid_schemes=None)

`txt`: A string to check validity
`throw`: Weather to throw an exception if `txt` does not represent a valid URL, `False` by default
`valid_schemes`: A string or an iterable (list, tuple or set). If provided, checks the given URL's scheme against this.

This utility function can be used to check if a string represents a valid URL address.

from frappe.utils import validate_url

validate_url('google') # False
validate_url('https://google.com') # True
validate_url('https://google.com', throw=True) # throws ValidationError

validate\email\address

validate_email_address(email_str, throw=False)

Returns a string containing the email address or comma-separated list of valid email addresses present in the given email_str. If throw is True, frappe.InvalidEmailAddressError is thrown in case of no valid email address in present in the given string else an empty string is returned.

from frappe.utils import validate_email_address

# Single valid email address
validate_email_address('rushabh@erpnext.com') # 'rushabh@erpnext.com'
validate_email_address('other text, rushabh@erpnext.com, some other text') # 'rushabh@erpnext.com'

# Multiple valid email address
validate_email_address(
 'some text, rushabh@erpnext.com, some other text, faris@erpnext.com, yet another no-emailic phrase.'
) # 'rushabh@erpnext.com, faris@erpnext.com'

# Invalid email address
validate_email_address('some other text') # ''

validate\phone\number

validate_phone_number(phone_number, throw=False)

Returns True if phone_number (string) is a valid phone number. If phone_number is invalid and throw is True, frappe.InvalidPhoneNumberError is thrown.

from frappe.utils import validate_phone_number

# Valid phone numbers
validate_phone_number('753858375') # True
validate_phone_number('+91-75385837') # True

# Invalid phone numbers
validate_phone_number('invalid') # False
validate_phone_number('87345%%', throw=True) # InvalidPhoneNumberError

frappe.cache()

cache()

Returns the redis connection, which is an instance of class RedisWrapper which is inherited from the redis.Redis class. You can use this connection to use the Redis cache to store/retrieve key-value pairs.

import frappe

cache = frappe.cache()

cache.set('name', 'frappe') # True
cache.get('name') # b'frappe'

frappe.sendmail()

sendmail(recipients=[], sender="", subject="No Subject", message="No Message", as_markdown=False, template=None, args=None, **kwargs)

`recipients`: List of recipients
`sender`: Email sender. Default is current user or default outgoing account
`subject`: Email Subject
`message`: (or `content`) Email Content
`as_markdown`: Convert content markdown to HTML
`template`: Name of html template (jinja) from templates/emails folder
`args`: Arguments for rendering the template

For most cases, the above arguments are sufficient but there are many other keyword arguments that can be passed to this function. To see all the keyword arguments, please have a look the implementation of this function (frappe/__init__.py).

This function can be used to send email using user's default Email Account or global default Email Account.

import frappe

recipients = [
 'gavin@erpnext.com',
 'hussain@erpnext.com'
]

frappe.sendmail(
 recipients=recipients,
 subject=frappe._('Birthday Reminder'),
 template='birthday_reminder',
 args=dict(
 reminder_text=reminder_text,
 birthday_persons=birthday_persons,
 message=message,
 ),
 header=_('Birthday Reminder 🎂')
)

Sample Jinja template file:





 {% for person in birthday_persons %}
 {% if person.image %}
 ![]({{ person.image }} "{{ person.name }}")
 {% endif %}
 {% endfor %}


{{ reminder_text }}
{{ message }}

Attaching Files

You can easily attach files to your email by passing a list of attachments to the sendmail function:

frappe.sendmail(
 ["faris@frappe.io", "hussain@frappe.io"],
 message="## hello, *bro*"
 attachments=[{"file_url": "/files/hello.png"}],
 as_markdown=True
)

Notice how attachments are a list of dictionaries having a key file_url. You can find this file_url in a File document's file_url field.

filelock

File lock can be used to synchronize processes to avoid race conditions.

Example: Writing to a file can cause race condition if multiple writers are trying to write to a file. So we create a named lock so processes can see the lock and wait until it's avialable for writing. 

from frappe.utils.synchronization import filelock

def update_important_config(config, file):
 with filelock("config_name"):
 json.dumps(config, file)
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