Continues the pattern of using custom Ecto types to create rich domain objects
and avoid primitive obsession. Adds two new custom types following the
established pattern from IPAddress.
## MacAddress Custom Type
Provides structured MAC address handling with:
- Multiple input format support (colon, hyphen, dot-separated, compact)
- Normalization to colon-separated lowercase (canonical format)
- SNMP binary format conversion (6-byte binary)
- Format conversion helpers (:colon, :hyphen, :dot, :compact)
- Comprehensive validation and error handling
### Supported Formats
- Colon: `00:11:22:33:44:55`
- Hyphen: `00-11-22-33-44-55`
- Dot (Cisco): `0011.2233.4455`
- Compact: `001122334455`
- SNMP binary: `<<0, 17, 34, 51, 68, 85>>`
All formats normalize to lowercase colon-separated format for consistency.
## SnmpOid Custom Type
Provides structured SNMP OID handling with:
- OID format validation (numeric and named)
- Normalization to dotted-decimal with leading dot
- OID resolution via SnmpKit (named → numeric)
- Helper functions (parent, child_of?, append)
- Integer list representation support
### Supported Formats
- Dotted-decimal: `.1.3.6.1.2.1.1.1.0`
- Numeric (no leading dot): `1.3.6.1.2.1.1.1.0`
- Named OID: `sysDescr.0` (with automatic resolution)
- Integer list: `[1, 3, 6, 1, 2, 1, 1, 1, 0]`
## Benefits
- **Type Safety**: Structured data with validation at cast time
- **Normalization**: Consistent storage format regardless of input
- **Rich API**: Helper functions for common operations
- **Zero Migration Cost**: No database changes needed
- **Better Errors**: Clear validation errors instead of DB constraint violations
- **Domain Modeling**: Code works with %MacAddress{} and %SnmpOid{} instead of strings
## Database Storage
Both types store as VARCHAR in the database:
- MacAddress: VARCHAR(17) - colon-separated format
- SnmpOid: VARCHAR(255) - dotted-decimal format with leading dot
## Test Coverage
Added comprehensive test suites:
- MacAddress: 47 tests covering all formats, roundtrips, edge cases
- SnmpOid: 49 tests covering OID operations, validation, helpers
- All 96 tests passing ✅
## Usage Example
```elixir
# Before (primitive obsession)
field :mac_address, :string
field :sensor_oid, :string
# After (rich domain types)
field :mac_address, Towerops.EctoTypes.MacAddress
field :sensor_oid, Towerops.EctoTypes.SnmpOid
# Usage
changeset
|> cast(attrs, [:mac_address, :sensor_oid])
# Validation happens automatically in cast/1
```
Files:
- lib/towerops/ecto_types/mac_address.ex (330 lines)
- lib/towerops/ecto_types/snmp_oid.ex (340 lines)
- test/towerops/ecto_types/mac_address_test.exs (380 lines)
- test/towerops/ecto_types/snmp_oid_test.exs (390 lines)