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47 lines
1.6 KiB
Markdown
47 lines
1.6 KiB
Markdown
# Error Handling in DDD
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This document defines error handling principles that apply across all layers and languages.
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## Core Principles
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1. **No Silent Failures** - All errors must be explicitly handled or propagated
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2. **Layer-Specific Errors** - Each layer defines its own error types
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3. **Error Transformation** - Errors are transformed at layer boundaries
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4. **Proper Logging** - Original errors logged before transformation
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5. **Result Types Over Exceptions** - Prefer Result types (where supported) over exceptions
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## Language-Specific Implementation
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- **Java**: See [languages/java/error-handling.md](../languages/java/error-handling.md)
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- **Go**: Use error returns and custom error types
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## Error Hierarchy
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```
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Domain Errors (business rule violations)
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↓ transformed at boundary
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Application Errors (use case failures)
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↓ transformed at boundary
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Infrastructure Errors (technical failures)
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```
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## Logging Strategy
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- **ERROR**: Infrastructure failures (database down, network error)
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- **WARN**: Business rule violations (insufficient funds, invalid state)
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- **INFO**: Normal operations (order placed, account created)
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- **DEBUG**: Detailed flow information
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- **TRACE**: Original errors when transforming between layers
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## Exception Boundary
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**Infrastructure Layer** is the exception boundary:
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- Infrastructure catches external exceptions (SQL, HTTP, etc.)
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- Transforms to domain error types
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- Logs original exception at ERROR level
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- Returns domain error type
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**Domain and Application** layers:
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- Never throw exceptions (use Result types or errors)
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- Only work with domain/application error types
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- No try/catch blocks needed
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