merge nested dictionary and list of dictionaries, python

Question

I would like to combine two nested dictionaries that have a slight structure (one is a list of dictionaries and the other one is a nested dictionary). I would very much appreciate your help!

GPP_projects =
[{'CompanyId': 61149,
  'Id': 44},
 {'CompanyId': 61307,
  'Id': 45}]

GPP_companies = 
{61149: {
  'Name': 'xyz',
  'CompanyId': 61149},
 61307: {
  'Name': 'abc',
  'CompanyId': 61307}}

#wanted outcome
GPP_combined =
[{'CompanyId': 61149,
  'Id': 44,
  'Name': 'xyz'}
 {'CompanyId': 61307,
  'Id': 45,
  'Name': 'abc'}}]

Answer 1

You could use a pandas approach or you could simply do the following

GPP_combined = [{**data, **GPP_companies.get(data['CompanyId'], {})} for data  in GPP_projects]

This will check if there is CompanyId in the GPP_companies dict, if so it will add it in. If there are no id in there GPP_companies it returns an empty dict which will do nothing.

Depending on what you want to do in the following cases:

• no CompanyId in GPP_companies ?
• if there are errors in GPP_companies which means {**a, **b} will over write valid fields in GPP_projects

output

GPP_projects =[{'CompanyId': 61149,
  'Id': 44},
 {'CompanyId': 61307,
  'Id': 45,}]

GPP_companies = {61149: {
  'Name': 'xyz',
  'CompanyId': 61149},
 61307: {
  'Name': 'abc',
  'CompanyId': 61307}}

#wanted outcome
GPP_combined =[{'CompanyId': 61149,
  'Id': 44,
  'Name': 'xyz'},
 {'CompanyId': 61307,
  'Id': 45,
  'Name': 'abc'}]

GPP_combined = [
{**data, **GPP_companies.get(data["CompanyId"], {})} 
for data in GPP_projects
]
"""
>> GPP_combined

[{'CompanyId': 61149, 'Id': 44, 'Name': 'xyz'},
 {'CompanyId': 61307, 'Id': 45, 'Name': 'abc'}]
"""

for python 2.7

for data in GPP_projects:
    company_id = data['CompanyId']
    company_obj = GPP_companies.get(company_id)
    if company_rec:
         data['Name'] = company_obj['Name']
         

This modified GPP_projects or you can do a copy to ensure that you are not modifying GPP_projects.