Use format options and remain with a string that I can format later again?

Question

I was working on a project and encountered an interesting situation. I'm reading some data from a file and use them to format/complete a string like this.

#After I read the file I create an internal dictionary to use, so for brevity 
#I'll use an example of the retrieved data
film = {"name":"Gran Torino", "type":"Drama"}

movie = "{name} is a {genre} movie. The vote given by {person} is {stars}"
movie = movie.format(name=film["name"],genre=film["type"])

This obviously generate an error, this one:

Traceback (most recent call last):
File "movie.py", line 65, in <module>
    movie = movie.format(name=film["name"],genere=film["type"])
KeyError: 'person'

because some keys are missing. The missing one will be retrieved from user when he will input them. I already know some way to evade the error, like format everything after I retrieved the other data from the user input.
However, I'm curious about something:

Is there a way in Python, using .format()/f-strings/string Template, for formatting a string with some initial value and maintain some missed places a later second passage? In other words can I insert only certain value and later the missing one?

Pseudo-code of what I try to achieve

string = "{first} text {second} ... and so on {last}"
#apply one time format but only one some place-holders
result = string.format(first=value) #dosen't need to generate an error
print(result) # "value text {second} ... and so on {last}"

Like you can see what I want is to know if in the language there is a way of doing this procedure with the built-in formatting options and without create a new function for this.

Side note:

I already tried to use some other options like string Template but wasn't able to make it work. Moreover, I know that is possible first concatenate the data in my possession, later add a string part and format later like this:

first_part = film["name"] + " is a " + film["genre"] + " movie."
second_part = "The vote given by {person} is {stars}"
movie = first_part + second_part
#later when I have stars and person
movie.format(person=v1,stars=v2)

This works, but I would love to understand if I can use two times format() method instead.

Answer 1

You could write a function that constructs the string for you. By default, it will use "unknown" as a string if an information is missing:

def str_constructor(name="unknown", genre="unknown", person="unknown", stars="unknown"):
    movie = "{} is a {} movie. The vote given by {} is {}".format(name, genre, person, stars)
    return movie

film = {"name":"Gran Torino", "type":"Drama"}
str_constructor(name=film["name"], type=film["type"])

Update:

Now that I fully understand your desired outcome, I have another option. An intuitive option to this would be:

string = "{name} is a {genre} movie. The vote given by {person} is {stars}"
film = {"name":"Gran Torino", "type":"Drama"}
print string.format(**film)

But this will raise an error, since there are variables missing in your formatting-dictionary.

In this answer a solution is given by constructing an individual formatter. Try this:

from string import Formatter

class UnseenFormatter(Formatter):
    def get_value(self, key, args, kwds):
        if isinstance(key, str):
            try:
                return kwds[key]
            except KeyError:
                return key
        else:
            return Formatter.get_value(key, args, kwds)

string = "{name} is a {genre} movie. The vote given by {person} is {stars}"
film = {"name":"Gran Torino", "type":"Drama"}

fmt = UnseenFormatter()
print fmt.format(string, **film)

...and you get:

Gran Torino is a genre movie. The vote given by person is stars

Later you can update your film dictionary to deliver the rest of your result.