How to update YAML file with value coming from a matching key in another dictionary?

Question

I have a YAML file called input.yaml:

---
'001':
  name: Ben
  email: ben@test.com
'002':
  name: Lisa
  email: lisa@test.com
'003':
  name: Alex
  email: alex@test.com
.
.
.

I have a dictionary:

my_dict = {'001': '000-111-2222', '002': '000-111-2223', '003': '000-111-2224', ...}

I would like to have an updated file called output.yaml that looks like this:

---
'001':
  name: Ben
  email: ben@test.com
  phone: 000-111-2222
'002':
  name: Lisa
  email: lisa@test.com
  phone: 000-111-2223
'003':
  name: Alex
  email: alex@test.com
  phone: 000-111-2224
.
.
.

Note how the output file has the "phone" field added with the value coming from the dictionary value of the matching key.

How do I get such file? ... I have tried all sorts.

Answer 1

If you are concerned that the format of the file stays the same (and if there are comments that they should be preserved), you can do:

import ruamel.yaml

yaml = ruamel.yaml.YAML()
yaml.preserve_quotes = True
yaml.explicit_start = True

with open('input.yaml') as fp:
    data = yaml.load(fp)

my_dict = {
    '001': '000-111-2222',
    '002': '000-111-2223',
    '003': '000-111-2224',
}

for k in my_dict:
    data.setdefault(k, {})['phone'] = my_dict[k]

with open('output.yaml', 'w') as fp:
    yaml.dump(data, fp)

After which output.yaml contains:

---
'001':
  name: Ben
  email: ben@test.com
  phone: 000-111-2222
'002':
  name: Lisa
  email: lisa@test.com
  phone: 000-111-2223
'003':
  name: Alex
  email: alex@test.com
  phone: 000-111-2224

Notes:

1. The yaml.preserve_quotes = True is not really necessary, as for scalars that need quotes ( your strings starting with zero ) single quotes are the default, and there are no superfluous quotes in your input either.

2. I use data.setdefault(k, {})['phone'] instead of checking if data[k] exists as @Aaron suggested in his source. It will create an (empty) dict if the key k is not in data.

3. If you only want to update matching keys, then use the following in the for loop:

   try:
       data[k]['phone'] = my_dict[k]
   except KeyError:
       pass
   

4. You need yaml.explicit_start = True to get the --- at the document start. ruamel.yaml doesn't automatically preserve that. If you need the document end marker (...) as well use: yaml.explicit_end = True

5. If you want the phone number to appear between name and email, then use:

   data.setdefault(k, {}).insert(1, 'phone', my_dict[k])
   

   which gives:

   ---
   '001':
     name: Ben
     phone: 000-111-2222
     email: ben@test.com
   '002':
     name: Lisa
     phone: 000-111-2223
     email: lisa@test.com
   '003':
     name: Alex
     phone: 000-111-2224
     email: alex@test.com
   

   (i.e. 0 means insert before the first key, 1 before the second key, etc.)

Answer 2

Aside from reading & writing to file, maybe this will point you in the right direction:

import yaml


document = """
---
'001':
  name: Ben
  email: ben@test.com
'002':
  name: Lisa
  email: lisa@test.com
'003':
  name: Alex
  email: alex@test.com
"""

phones = {'001': '000-111-2222', '002': '000-111-2223', '003': '000-111-2224'}

doc = yaml.safe_load(document)

for k, v in phones.items():
    # Might want to check that 'doc[k]' exists
    doc[k]['phone'] = v

print(yaml.safe_dump(doc, default_flow_style=False, explicit_start=True))

Output:

'001':
  email: ben@test.com
  name: Ben
  phone: 000-111-2222
'002':
  email: lisa@test.com
  name: Lisa
  phone: 000-111-2223
'003':
  email: alex@test.com
  name: Alex
  phone: 000-111-2224