how to file.write() an empty string if dictionary produces a KeyError in python -

i have particular problem json files. following code reads json, , writes txt file. have shortened code readability, in real code hundereds of fields , write statements.

import os import json   def _getjson(filename):     """ returns list of dictionaries """     if not os.path.exists(filename): return []     open(filename, 'r') openfileobject:         data = json.loads(openfileobject.read())     return data  def writefile(filename, data):     """writes file"""     open(filename, 'w') f:         d in data:             f.write(d['field1'] + ' ' + d['field2'] + ' ' + d['field3'] + '\n')             ## lot more code here   def main():     filename = r'c:\input.json'     data = _getjson(filename)     outfile = r'c:\output.txt'     writefile(outfile, data)  if __name__ == '__main__':     main() 

the problem is, field not in json, , produces keyerror while can trap try: except keyerror. mean need put try around every field in writefile function.

is there way without changing f.write() statements, upon keyerror write empty string ? (so not have capture in hundereds of try blocks)

so dictionary problem, have no problem json itself. cannot control fields in input, 1 file may have field1 , field2. next have three, or one. json part works, missing fields, sometimes.

use dict.get:

f.write(d.get('field1', '') + ' ' +         d.get('field2', '') + ' ' +         d.get('field3', '') + '\n') 

get() returns value key, or given default or none.