Rules in Deply

Rules in Deply define how different layers in your architecture can interact with each other. This document explains the different types of rules and how to use them effectively.

Rule Types

Layer Dependency Rules

Control which layers can depend on other layers:

ruleset:
  views:
    disallow_layer_dependencies:
      - models

Function Decorator Rules

Enforce the use of specific decorators on functions:

ruleset:
  tasks:
    enforce_function_decorator_usage:
      - type: function_decorator_name_regex
        decorator_name_regex: "app.task"

Class Inheritance Rules

Ensure classes inherit from specific base classes:

ruleset:
  models:
    enforce_inheritance:
      - type: bool
        any_of:
          - type: class_inherits
            base_class: "django.db.models.Model"
          - type: class_inherits
            base_class: "django.contrib.auth.models.AbstractUser"

Rule Configuration

Rules are defined in the ruleset section of your deply.yaml configuration file:

deply:
  ruleset:
    layer_name:
      rule_type:
        - rule_configuration

Common Rule Patterns

Preventing Direct Model Access

ruleset:
  views:
    disallow_layer_dependencies:
      - models
  controllers:
    disallow_layer_dependencies:
      - models

Enforcing Service Layer Pattern

ruleset:
  views:
    disallow_layer_dependencies:
      - models
      - repositories
    allow_layer_dependencies:
      - services

Ensuring Task Decorators

ruleset:
  tasks:
    enforce_function_decorator_usage:
      - type: function_decorator_name_regex
        decorator_name_regex: "app.task"

Best Practices

1. Start with basic layer dependency rules
2. Add more specific rules as needed
3. Document the reasoning behind complex rules
4. Review and update rules regularly
5. Use rules to enforce team conventions

Rule Violations

When rules are violated, Deply will report them in the following format:

/path/to/file.py:line_number - Layer 'layer_name' is not allowed to depend on layer 'other_layer'

For more information about configuring rules, please refer to the Configuration Guide.