[bug] settings.local.toml tree overrides settings.toml

Describe the bug If I define a conf variable “A.B.C” in one file and another conf variable “A.cousin.D” in another file, then “A.B.C” is erased.

To Reproduce Steps to reproduce the behavior:

1. Having the following folder structure

Project structure

$ ls -alh
total 24K
drwxrwxr-x   2 user group 4,0K Jan 15 18:34 ./
drwxr-xr-x 109 user group 4,0K Jan 15 17:31 ../
-rw-rw-r--   1 user group   75 Jan 15 18:27 dynaconf_test.py
-rw-rw-r--   1 user group   16 Jan 15 18:34 requirements.txt
-rw-rw-r--   1 user group   45 Jan 15 18:28 settings.local.toml
-rw-rw-r--   1 user group   40 Jan 15 18:27 settings.toml

1. Having the following config files:

Config files

$ echo $ENV_FOR_DYNACONF

and

/path/settings.toml

[default]

[development.A.B]
  C = "1"

/path/settings.local.toml

[default]

[development.A.cousin]
  D = "2"

/path/requirements.txt

dynaconf==v2.2.2

1. Having the following app code:

Code

/path/dynaconf_test.py

from dynaconf import settings

print(settings.get('A').get('B').get('C'))

1. Executing under the following environment:

Execution

$ python3 --version
Python 3.6.9

$ python3 -m pip install --user --upgrade pip
Requirement already up-to-date: ...
$ python3 -m pip install --user --upgrade virtualenv
Requirement already up-to-date:
$ python3 -m virtualenv -p python3 venv
Already using interpreter /usr/bin/python3
Using base prefix '/usr'
[...]
Installing setuptools, pip, wheel...
done.

$ source venv/bin/activate
$ python3 -m pip install --quiet -r requirements.txt

Expected behavior Same as if I remove settings.local.toml or merge the two file together.

$ python dynaconf_test.py
1

Actual behavior

$ python dynaconf_test.py
Traceback (most recent call last):
  File "dynaconf_test.py", line 3, in <module>
    print(settings.get('A').get('B').get('C'))
AttributeError: 'NoneType' object has no attribute 'get'

Debug output

Debug Output

# export `DEBUG_LEVEL_FOR_DYNACONF=DEBUG` reproduce your problem and paste the output here
2020-01-15:18:44:51,460 DEBUG    [base.py:86 - _read] toml_loader: /path/settings.toml
2020-01-15:18:44:51,460 DEBUG    [base.py:159 - _read] toml_loader: settings.toml[default]{}
2020-01-15:18:44:51,460 DEBUG    [base.py:159 - _read] toml_loader: settings.toml[development]{'A': {'B': {'C': '1'}}}
2020-01-15:18:44:51,460 DEBUG    [base.py:86 - _read] toml_loader: /path/settings.local.toml
2020-01-15:18:44:51,460 DEBUG    [base.py:159 - _read] toml_loader: settings.local.toml[default]{}
2020-01-15:18:44:51,460 DEBUG    [base.py:159 - _read] toml_loader: settings.local.toml[development]{'A': {'cousin': {'D': '2'}}}
2020-01-15:18:44:51,461 DEBUG    [base.py:902 - execute_loaders] Dynaconf executing: dynaconf.loaders.env_loader
2020-01-15:18:44:51,461 DEBUG    [base.py:905 - execute_loaders] Loaded Files: ['/path/settings.toml', '/path/settings.local.toml']
2020-01-15:18:44:51,461 DEBUG    [base.py:129 - _setup] Lazy Settings _setup ...
Traceback (most recent call last):
  File "dynaconf_test.py", line 3, in <module>
    print(settings.get('A').get('B').get('C'))
AttributeError: 'NoneType' object has no attribute 'get'

Environment (please complete the following information):

• OS: Linux Mint 19 (based on Ubuntu Bionic Beaver)
• Dynaconf Version: 2.2.2
• Frameworks in use: None

Additional context If I remove the file settings.local.toml then it works fine:

$ rm settings.local.toml
$ python dynaconf_test.py
1

[rochacbruno]

This is not a bug!

To have data merged it is needed to explicitly set a merge strategy

It can be a global

settings = Dynaconf(
    settings_file="settings.toml",
    environments=True,
    merge_enabled=True  # this enabled global merge of all files
)

Or a local direct in the settings.local.toml file.

# to explicitly merge a file into existing data it should contain merge token
dynaconf_merge = true

[default]

[development.A.cousin]
D = "2"

[rochacbruno]

And documentation is on https://www.dynaconf.com/merging/#local-configuration-files-and-merging-to-existing-data