Let the user create a custom format using a string - python-3.x

Question

I'd like a user to be able to create a custom format in QtWidgets.QPlainTextEdit() and it would format the string and split out the results in another QtWidgets.QPlainTextEdit().
For example:
movie = {
"Title":"The Shawshank Redemption",
"Year":"1994",
"Rated":"R",
"Released":"14 Oct 1994",
"Runtime":"142 min",
"Genre":"Drama",
"Director":"Frank Darabont",
"Writer":"Stephen King (short story \"Rita Hayworth and Shawshank Redemption\"),Frank Darabont (screenplay)",
"Actors":"Tim Robbins, Morgan Freeman, Bob Gunton, William Sadler",
"Plot":"Two imprisoned men bond over a number of years, finding solace and eventual redemption through acts of common decency.",
"Language":"English",
"Country":"USA",
"Awards":"Nominated for 7 Oscars. Another 21 wins & 36 nominations.",
"Poster":"https://m.media-amazon.com/images/M/MV5BMDFkYTc0MGEtZmNhMC00ZDIzLWFmNTEtODM1ZmRlYWMwMWFmXkEyXkFqcGdeQXVyMTMxODk2OTU#._V1_SX300.jpg",
"Ratings": [
{
"Source":"Internet Movie Database",
"Value":"9.3/10"
},
{
"Source":"Rotten Tomatoes",
"Value":"91%"
},
{
"Source":"Metacritic",
"Value":"80/100"
}
],
"Metascore":"80",
"imdbRating":"9.3",
"imdbVotes":"2,367,380",
"imdbID":"tt0111161",
"Type":"movie",
"DVD":"15 Aug 2008",
"BoxOffice":"$28,699,976",
"Production":"Columbia Pictures, Castle Rock Entertainment",
"Website":"N/A"
}
custom_format = '[ {Title} | ⌚ {Runtime} | ⭐ {Genre} | 📅 {Released} | {Rated} ]'.format(Title=movie['Title'], Runtime=movie['Runtime'], Genre=movie['Genre'],Released=movie['Released'],Rated=movie['Rated'])
print(custom_format)
This code above, would easily print [ The Shawshank Redemption | ⌚ 142 min | ⭐ Drama | 📅 14 Oct 1994 | R ].
However, if I change this code from:
custom_format = '[ {Title} | ⌚ {Runtime} | ⭐ {Genre} | 📅 {Released} | {Rated} ]'.format(Title=movie['Title'], Runtime=movie['Runtime'], Genre=movie['Genre'],Released=movie['Released'],Rated=movie['Rated'])
To:
custom_format = "'[ {Title} | ⌚ {Runtime} | ⭐ {Genre} | 📅 {Released} | {Rated} ]'.format(Title=movie['Title'], Runtime=movie['Runtime'], Genre=movie['Genre'],Released=movie['Released'],Rated=movie['Rated'])"
Notice, that the whole thing is wrapped in "". Therefor its a string. Now doing this will not print out the format that I want.
The reason I wrapped it in "" is because when I add my original custom_format into a QtWidgets.QPlainTextEdit(), it converts it into a string it wont format later on.
So my original idea was, the user creates a custom format for themselves in a QtWidgets.QPlainTextEdit(). Then I copy that format, open a new window wher the movie json variable is contained and paste the format into another QtWidgets.QPlainTextEdit() where it would hopefuly show it formatted correctly.
Any help on this would be appreciated.
ADDITIONAL INFORMATION:
User creates their format inside QtWidgets.QPlainTextEdit().
Then the user clicks Test Format which should display [ The Shawshank Redemption | ⌚ 142 min | ⭐ Drama | 📅 14 Oct 1994 | R ] but instead it displays

Answer 1

Trying to use the full format command would require an eval(), which is normally considered not only bad practice, but also a serious security issue, especially when the input argument is completely set by the user.
Since the fields are known, I see little point in providing the whole format line, and it is better to parse the format string looking for keywords, then use keyword lookup to create the output.
class Formatter(QtWidgets.QWidget):
def __init__(self):
super().__init__()
layout = QtWidgets.QVBoxLayout(self)
self.formatBase = QtWidgets.QPlainTextEdit(
'[ {Title} | ⌚ {Runtime} | ⭐ {Genre} | 📅 {Released} | {Rated} ]')
self.formatOutput = QtWidgets.QPlainTextEdit()
layout.addWidget(self.formatBase)
layout.addWidget(self.formatOutput)
self.formatBase.textChanged.connect(self.processFormat)
self.processFormat()
def processFormat(self):
format_str = self.formatBase.toPlainText()
# escape double braces
clean = re.sub('{{', '', re.sub('}}', '', format_str))
# capture keyword arguments
tokens = re.split(r'\{(.*?)\}', clean)
keywords = tokens[1::2]
try:
# build the dictionary with given arguments, unrecognized keywords
# are just printed back in the {key} form, in order let the
# user know that the key wasn't valid;
values = {k:movie.get(k, '{{{}}}'.format(k)) for k in keywords}
self.formatOutput.setPlainText(format_str.format(**values))
except (ValueError, KeyError):
# exception for unmatching braces
pass