format string based on conditions - python-3.x

Question

I am trying to create a mail body template dynamically based on some conditions.
body = """ New product has created by {user}
This can be viewed by clicking here {link}
Logs is here {link2}
"""
I need to format this string based on some conditions, like:
if 'user' in params:
body.format(user='username')
if 'link' in params:
body.format(link='new link')
if 'link2' in params:
body.format(link2='new link2')
I know I can do like below,
body.format(user='username',link='new link',link2='new link2')
But i have to do this based on the above conditions. Is there any way to achieve this in python.?
I have found this and this didn't
help me.
Thanks in advance.

Answer 1

Yeah, I said to use lambdas in my comment but defining a function would be better for expandability. Here's your code:
def format_template(*args):
user = 'default'
link = 'something'
link2 = 'something2'
if 'user' in args:
user = 'username'
elif 'link' in args:
link = 'link'
elif 'link2' in args:
link2 = 'link2'
body = f"""
New product has created by {user}
This can be viewed by clicking here {link}
Logs is here {link2}
"""
return body

Answer 2

What about something like this?
params.setdefault('user', 'unknown user')
params.setdefault('link', 'unknown link')
params.setdefault('link2', 'unknown log link')
body = """ New product has created by {user}
This can be viewed by clicking here {link}
Logs is here {link2}
""".format(**params)
Of course you can change the defaults ('unknown user', etc.) to whatever value you deem appropriate. If you're not allowed to modify params, you can also use params2=dict(params) and then operate on params2 instead.

Answer 3

What's wrong with the question you linked? This seems like it would work:
body = """ New product has created by {user}
This can be viewed by clicking here {link}
Logs is here {link2}
""".format(user='username' if 'user' in params else '???',
link='new link' if 'link' in params else '???',
link2='new link2' if 'link2' in params else '???')

Answer 4

You can try like this.
Here params is a dictionary so you can iterate over its items and do the replacement.
>>> def format(body, **params):
... for key, value in params.items():
... rep = "{" + key + "}"
... if rep in body:
... body = body.replace(rep, value)
... return body
...
>>>
>>> body = """ New product has created by {user}
... This can be viewed by clicking here {link}
... Logs is here {link2}
... """
>>>
>>> print(format(body, user='username'))
New product has created by username
This can be viewed by clicking here {link}
Logs is here {link2}
>>> print(format(body, link='new link'))
New product has created by {user}
This can be viewed by clicking here new link
Logs is here {link2}
>>> print(format(body, link2='new link2'))
New product has created by {user}
This can be viewed by clicking here {link}
Logs is here new link2
>>>
>>> print(format(body, link2='new link2', link="new link"))
New product has created by {user}
This can be viewed by clicking here new link
Logs is here new link2
>>> print(format(body, link2='new link2', link="new link", user="username"))
New product has created by username
This can be viewed by clicking here new link
Logs is here new link2
>>>