domain.validators.registry

src.domain.validators.registry

Validation Rules Registry (F8.4).

Single source of truth for all validation rules with self-enforcing compliance tests.

This registry follows the same architectural pattern as: - F7.7: Domain Events Registry (metadata-driven, auto-wiring) - F8.1: Provider Registry (single source of truth, 100% coverage) - F8.3: Rate Limit Registry Compliance (self-enforcing validation)

Pattern: Registry Pattern with metadata catalog and helper functions.

Reference

• docs/architecture/validation-registry-architecture.md
• docs/architecture/registry-pattern-architecture.md

Classes

ValidationCategory

Bases: str, Enum

Categories for validation rules.

Used to group validators by their domain purpose.

Source code in src/domain/validators/registry.py

class ValidationCategory(str, Enum):
    """Categories for validation rules.

    Used to group validators by their domain purpose.
    """

    AUTHENTICATION = "authentication"  # Email, Password, Tokens
    API_PARAMETERS = "api_parameters"  # UUIDs, booleans, filters (future)
    PROVIDER_DATA = "provider_data"  # Provider-specific validation (future)
    DOMAIN_VALUES = "domain_values"  # Money, dates, etc. (future)

ValidationRuleMetadata dataclass

Metadata for a single validation rule.

Contains all information needed to use a validator: function, constraints, documentation, and examples.

Attributes:

Name	Type	Description
rule_name	str	Unique identifier for the rule (e.g., 'email', 'password').
validator_function	Callable[[str], str]	Callable that validates input and returns validated value.
field_constraints	dict[str, int | str]	Pydantic Field constraints (min_length, max_length, pattern).
description	str	Human-readable description of validation requirements.
examples	list[str]	List of valid example values.
category	ValidationCategory	Category for grouping (AUTHENTICATION, API_PARAMETERS, etc.).

Example

metadata = ValidationRuleMetadata( ... rule_name="email", ... validator_function=validate_email, ... field_constraints={"min_length": 5, "max_length": 255}, ... description="Email address with format validation", ... examples=["user@example.com"], ... category=ValidationCategory.AUTHENTICATION, ... )

Source code in src/domain/validators/registry.py

@dataclass(frozen=True, kw_only=True)
class ValidationRuleMetadata:
    """Metadata for a single validation rule.

    Contains all information needed to use a validator: function, constraints,
    documentation, and examples.

    Attributes:
        rule_name: Unique identifier for the rule (e.g., 'email', 'password').
        validator_function: Callable that validates input and returns validated value.
        field_constraints: Pydantic Field constraints (min_length, max_length, pattern).
        description: Human-readable description of validation requirements.
        examples: List of valid example values.
        category: Category for grouping (AUTHENTICATION, API_PARAMETERS, etc.).

    Example:
        >>> metadata = ValidationRuleMetadata(
        ...     rule_name="email",
        ...     validator_function=validate_email,
        ...     field_constraints={"min_length": 5, "max_length": 255},
        ...     description="Email address with format validation",
        ...     examples=["user@example.com"],
        ...     category=ValidationCategory.AUTHENTICATION,
        ... )
    """

    rule_name: str
    validator_function: Callable[[str], str]
    field_constraints: dict[str, int | str]
    description: str
    examples: list[str]
    category: ValidationCategory

Functions

get_validation_rule

get_validation_rule(
    rule_name: str,
) -> ValidationRuleMetadata | None

Get validation rule metadata by name.

Parameters:

Name	Type	Description	Default
rule_name	str	Name of the validation rule (e.g., 'email', 'password').	required

Returns:

Type	Description
ValidationRuleMetadata | None	ValidationRuleMetadata if found, None otherwise.

Example

rule = get_validation_rule("email") if rule: ... validated = rule.validator_function("user@example.com")

Source code in src/domain/validators/registry.py

def get_validation_rule(rule_name: str) -> ValidationRuleMetadata | None:
    """Get validation rule metadata by name.

    Args:
        rule_name: Name of the validation rule (e.g., 'email', 'password').

    Returns:
        ValidationRuleMetadata if found, None otherwise.

    Example:
        >>> rule = get_validation_rule("email")
        >>> if rule:
        ...     validated = rule.validator_function("user@example.com")
    """
    return VALIDATION_RULES_REGISTRY.get(rule_name)

get_all_validation_rules

get_all_validation_rules() -> list[ValidationRuleMetadata]

Get all validation rules in the registry.

Returns:

Type	Description
list[ValidationRuleMetadata]	List of all ValidationRuleMetadata objects.

Example

all_rules = get_all_validation_rules() print(f"Total rules: {len(all_rules)}")

Source code in src/domain/validators/registry.py

def get_all_validation_rules() -> list[ValidationRuleMetadata]:
    """Get all validation rules in the registry.

    Returns:
        List of all ValidationRuleMetadata objects.

    Example:
        >>> all_rules = get_all_validation_rules()
        >>> print(f"Total rules: {len(all_rules)}")
    """
    return list(VALIDATION_RULES_REGISTRY.values())

get_rules_by_category

get_rules_by_category(
    category: ValidationCategory,
) -> list[ValidationRuleMetadata]

Get all validation rules in a specific category.

Parameters:

Name	Type	Description	Default
category	ValidationCategory	Category to filter by (AUTHENTICATION, API_PARAMETERS, etc.).	required

Returns:

Type	Description
list[ValidationRuleMetadata]	List of ValidationRuleMetadata objects in the category.

Example

auth_rules = get_rules_by_category(ValidationCategory.AUTHENTICATION) print(f"Auth rules: {len(auth_rules)}")

Source code in src/domain/validators/registry.py

def get_rules_by_category(category: ValidationCategory) -> list[ValidationRuleMetadata]:
    """Get all validation rules in a specific category.

    Args:
        category: Category to filter by (AUTHENTICATION, API_PARAMETERS, etc.).

    Returns:
        List of ValidationRuleMetadata objects in the category.

    Example:
        >>> auth_rules = get_rules_by_category(ValidationCategory.AUTHENTICATION)
        >>> print(f"Auth rules: {len(auth_rules)}")
    """
    return [
        rule for rule in VALIDATION_RULES_REGISTRY.values() if rule.category == category
    ]

get_statistics

get_statistics() -> dict[str, int | dict[str, int]]

Get registry statistics.

Returns:

Type	Description
dict[str, int | dict[str, int]]	Dictionary with:
dict[str, int | dict[str, int]]	total_rules: Total number of rules
dict[str, int | dict[str, int]]	by_category: Count of rules per category

Example

stats = get_statistics() print(f"Total: {stats['total_rules']}") print(f"Auth: {stats['by_category']['authentication']}")

Source code in src/domain/validators/registry.py

def get_statistics() -> dict[str, int | dict[str, int]]:
    """Get registry statistics.

    Returns:
        Dictionary with:
        - total_rules: Total number of rules
        - by_category: Count of rules per category

    Example:
        >>> stats = get_statistics()
        >>> print(f"Total: {stats['total_rules']}")
        >>> print(f"Auth: {stats['by_category'][`'authentication'`]}")
    """
    rules = list(VALIDATION_RULES_REGISTRY.values())
    category_counts: dict[str, int] = {}

    for rule in rules:
        category_key = rule.category.value
        category_counts[category_key] = category_counts.get(category_key, 0) + 1

    return {
        "total_rules": len(rules),
        "by_category": category_counts,
    }