updateConnStrings.py

import json
import sys
#from pprint import pprint as pretty

# read json
def read_json(appSettingsFile):
    with open(appSettingsFile) as data_file:
        data = json.load(data_file)
#    pretty(data)
    return data

# write json
def write_json(data, appSettingsFile, depth=2):
    with open(appSettingsFile, 'w') as data_file:
        json.dump(data, data_file, indent=depth, sort_keys=False)

def validate_pattern(data, keyName):
    # validate that ConnString key exists
    if 'ConnectionStrings' not in data:
        raise KeyError('No ConnectionStrings in target file.')

    # validate if key name to lookup exists in ConnectionStrings dict
    if keyName not in data['ConnectionStrings']:
        raise KeyError('No ConnectionStrings key ' + keyName + ' in target file.')

def main(appSettingsFile: str, keyName: str, connectionStringValue: str):
    # read json into variable
    data = read_json(appSettingsFile)

    # validate_pattern(appSettingsFile,keyName)
    validate_pattern(data, keyName)

    # walk key/values in data object
    for k,v in data.items():
        # if doc contains ConnectionStrings update value based on key name
        if 'ConnectionStrings' in k:
            try:
                v[str(keyName)] = connectionStringValue.format(k)
                print("Connection string key " + keyName + " value updated.")
            except:
                print("Failed to update " + keyName + " connection string.")

    # update appsettings
    write_json(data, appSettingsFile)

# Map command line arguments to function arguments.
if __name__ == '__main__':
    main(*sys.argv[1:])