Custom conflict resolver

When importing dump data into local DB, some rows may refer to the same object (e.g. two Task rows with hte same value of "name" column). This class contains default logic to resolve such merging conflicts (implemented for all currently present DBs).

To change this default behavior, you can write your own coflict resolver class:

1. Add a new Python module next to this module (e.g. my_conflict_resolver)

2. This module must contain a class (e.g. MyMergeConflictResolver) that inherits from either BaseMergeConflictResolver or default resolver DefaultMergeConflictResolver (also in this directory)

   from .base_merge_conflict_resolver import BaseMergeConflictResolver
   
   class CustomMergeConflictResolver(BaseMergeConflictResolver):
       default_strategy_name = "..."
       strategies_config = {...}

3. To use this newly created class, specify its name in import command: mephisto db import ... --conflict-resolver MyMergeConflictResolver

The easiest place to start customization is to modify strategies_config property, and perhaps default_strategy_name value (see DefaultMergeConflictResolver as an example).

NOTE: All available providers must be present in strategies_config. Table names (under each provider key) are optional, and if missing, default_strategy_name will be used for all conflicts related to this table.

4. There is an example of a working custom conflict resolver in module mephisto/tools/db_data_porter/conflict_resolvers/example_merge_conflict_resolver.py. You can launch it like this:

mephisto db import ... --conflict-resolver ExampleMergeConflictResolver