DEPLOY SPRINT - Ticket 01 - Implement max_models_by_field and unique constraints

[b-rad-c]

DEPLOY SPRINT - Ticket 01 - Implement max_models_by_field and unique constraints

Branch: improve-sosh-net-ui

Overview

Implement max_models_by_field in the model auth spec, similar to max_models_per_user. This allows limiting the number of models a user can create where a specific field value is the same — e.g., "only 1 reaction per user per post".

Also implement the unique field-level constraint so that the DB enforces only one row with a given value per column (e.g., one username per profile table).

Background

The updated sosh-net.yaml on improve-sosh-net-ui defines:

reaction:
  auth:
    require_login: true
    max_models_by_field:
      post_id: 1  # only allow one reaction per user per post

And for profile:

username:
  type: str
  unique: true

Implementation

max_models_by_field

1. src/mspec/core.py — In load_generator_spec, initialise max_models_by_field to {} in the auth block alongside max_models_per_user

2. src/mapp/module/model/db.py — db_model_create — After the existing max_models_per_user check, iterate max_models_by_field:

   for field_name, max_count in model_spec['auth']['max_models_by_field'].items():
       if max_count >= 0:
           field_value = getattr(obj, field_name)
           count = ctx.db.cursor.execute(
               f'SELECT COUNT(*) FROM {model_snake_case} WHERE user_id = ? AND "{field_name}" = ?',
               (user['value']['id'], field_value)
           ).fetchone()[0]
           if count >= max_count:
               raise MappUserError('MAX_MODELS_BY_FIELD_EXCEEDED',
                   f'Maximum models ({max_count}) for field {field_name} exceeded.')

unique field constraint

1. src/mapp/module/model/db.py — db_model_create_table — Append UNIQUE to the column definition string for any non-list field with unique: true in the field spec

Tests

• Add a model to src/mspec/data/generator/model-type-testing.yaml with max_models_by_field set; verify a second model with the same field value returns HTTP 400
• Add a field with unique: true to the test yaml; verify duplicate values are rejected with a DB constraint error
• Update src/mapp/test.py to cover the MAX_MODELS_BY_FIELD_EXCEEDED error case (pattern: existing max_models_per_user test at line ~309)

Documentation

• Update docs/LINGO_MAPP_SPEC.md:
  • Document auth.max_models_by_field under the auth section
  • Document the unique field attribute under the fields section

References

• Existing max_models_per_user implementation: src/mapp/module/model/db.py:107
• db_model_create_table for unique constraint: src/mapp/module/model/db.py:19
• Spec loading: src/mspec/core.py:376