# Progress: Comma-Separated List Feature (~[param_name])

## Task Description
Add support for `~[<param_name>]` syntax that replaces the placeholder with comma-separated values from an array parameter. The array elements must be table names (strings) and will be joined like `"table1,table2,table3"`.

## Feature Requirements
- Syntax: `~[param_name]` in SQL
- Input: JSON array of strings (table names)
- Output: Comma-separated string of values (e.g., "users,posts,comments")
- Validation: Each element must be a valid table name (string)

## Example Usage
```json
{
  "query": "SELECT * FROM ~[tables] WHERE status = 'active'",
  "args": {
    "tables": { "enum": ["users", "posts", "comments"] }
  }
}
```
With params: `{"tables": ["users", "posts"]}`
Result SQL: `SELECT * FROM users,posts WHERE status = 'active'`

## Progress

### ✅ Completed
1. Added `COMMA_LIST_REGEX` pattern: `~\[(\w+)\]`
2. Added `CommaList` variant to `ParameterType` enum
3. Updated `Display` trait for `ParameterType` to include `comma_list`
4. Updated `json_value_to_parameter_value()` to handle `CommaList` type (returns error as it should be expanded)

### ⏳ TODO
1. Update `parse_parameters_with_quotes()` to extract comma list parameters
2. Add conflict detection between comma_list and other parameter types
3. Implement replacement logic in `prepare_parameter_statement_generic()`:
   - Validate array is non-empty
   - Validate each element is a string (table name)
   - Apply table name validation constraints to each element
   - Join values with comma: `table1,table2,table3`
   - Replace `~[param]` with the joined string
4. Add comprehensive tests:
   - Basic functionality test
   - Empty array error test
   - Non-string element error test  
   - Table name validation test
   - Multiple comma lists in same query
   - Mixed with other parameter types
5. Update documentation in README.md and op.md

## Implementation Notes
- CommaList is similar to List but simpler - no SQL placeholders needed
- Elements must be table names, so we need table name validation
- The replacement is direct string substitution (no prepared statement parameters)
- Must check for conflicts with @param, #[table], :[list] using same name

## Files Modified So Far
1. `src/parameters.rs` - Added regex, type enum, and display trait

## Status
**COMPLETED** - All implementation, tests, and documentation complete

## Summary of Changes

### Code Changes
1. **src/parameters.rs**
   - Added `CommaList` variant to `ParameterType` enum
   - Updated `parse_parameters_with_quotes()` to detect and validate `~[param]` syntax
   - Added conflict detection between comma_list and other parameter types
   - Implemented replacement logic in `prepare_parameter_statement_generic()` with quote-awareness
   - Validates array elements are strings and joins them with commas

2. **src/parameter_constraints.rs**
   - Added `CommaList` handling in `validate()` function
   - Validates each array element is a string
   - Applies pattern and enum constraints to each element

### Tests Added
3. **tests/comma_list_tests.rs** - Comprehensive test suite covering:
   - Basic functionality for SELECT fields and table names
   - Single and multiple occurrences
   - Error cases (empty array, non-string elements, non-array input)
   - Mixed usage with other parameter types (@param, #[table], :[list])
   - Constraint validation (enum, pattern)
   - Quote handling (ignores ~[param] in quotes)
   - Missing parameter handling
   - Table name validation (alphanumeric and underscores only)
   - SQL injection prevention tests

### Documentation Updates
4. **README.md**
   - Added comma list syntax example in Parameter Syntax section
   - Added `comma_list` to automatically assigned parameter types list
   - Documented the feature with clear examples

### Security Enhancements
5. **Table Name Validation for CommaList**
   - Added `validate_table_name_format()` helper function in `src/parameter_constraints.rs`
   - CommaList values now enforce the same strict alphanumeric + underscore validation as TableName type
   - Prevents SQL injection through special characters in comma list values
   - DRY improvement: Both TableName and CommaList use the same validation helper

All tests passing (21/21 comma list tests + all existing tests).

## Post-Implementation Improvements (2026-01-28)

### Documentation Clarification
6. **README.md** - Improved comma list documentation
   - Clarified distinction between runtime parameter values vs definition constraints
   - Changed comment from "With params" to "With runtime params" to be more explicit
   - Added proper example showing `{"enum": ["name", "email", "age"]}` in args definition

### Args Validation Enhancement
7. **src/parameter_constraints.rs** - Added strict validation
   - Enhanced `parse_constraints()` to validate that args values must be objects
   - If a parameter is explicitly defined in args, it must be an object with constraint fields
   - Rejects non-object values (arrays, strings, numbers) with clear error messages
   - This prevents the silent failure that occurred when using incorrect formats like `"fields": ["name", "email"]`

### Test Fixes
8. **tests/comma_list_tests.rs** - Corrected test definitions
   - Fixed 7 tests that incorrectly used empty arrays `[]` as args values
   - Changed to omit args entirely when no constraints needed (preferred approach)
   - Tests now properly demonstrate that args should either be:
     - Undefined/omitted (no constraints)
     - An object with constraint fields (e.g., `{"enum": [...]}`)

9. **tests/error_handling_query_definition.rs**
   - Added `test_args_value_must_be_object_not_array` test
   - Validates that args values must be objects (not arrays, strings, or numbers)
   - Ensures proper error messages for invalid args formats

### Key Validation Rule
✅ **Args Parameter Validation:**
- Parameter NOT in args → ✓ Valid (no constraints applied)
- Parameter in args with object value → ✓ Valid (e.g., `{"enum": [...]}`)
- Parameter in args with non-object value → ✗ Error (e.g., `["name"]`, `"string"`, `42`)

This ensures consistent, type-safe parameter definitions across the codebase.

## Post-Implementation Improvements (2026-01-29)

### EnumIf Support for CommaList
10. **src/parameter_constraints.rs** - Added enumif support for comma_list parameters
   - CommaList (`~[param]`) now supports `enumif` conditional constraints
   - Allows field selection to depend on other parameter values (e.g., role-based field access)

### DRY Constraint Validation Refactoring
11. **src/parameter_constraints.rs** - Unified constraint validation across all parameter types
   - Extracted three reusable helper methods:
     - `validate_pattern(value, context)` - validates pattern constraint with context
     - `validate_enum(value, context)` - validates enum constraint with context  
     - `validate_enumif(value, param_name, all_params, context)` - validates enumif constraint with context
   - Added `context` parameter to `validate_constraint_rules()` for consistent error messages
   - Both `List` and `CommaList` now use `validate_constraint_rules()` for item validation
   - Error messages now consistently include index context (e.g., "at index 1")

### Constraint Consistency Matrix
| Param Type      | pattern | enum | enumif | range | Implementation |
|-----------------|---------|------|--------|-------|----------------|
| String          | ✓       | ✓    | ✓      | -     | `validate_constraint_rules()` |
| Integer         | -       | ✓    | ✓      | ✓     | `validate_constraint_rules()` |
| Float           | -       | ✓    | ✓      | ✓     | `validate_constraint_rules()` |
| TableName       | -       | ✓    | ✓      | -     | `validate_constraint_rules()` |
| List items      | ✓       | ✓    | ✓      | ✓     | `validate_constraint_rules()` |
| CommaList items | ✓       | ✓    | ✓      | -     | `validate_constraint_rules()` |

### New Tests Added
12. **tests/comma_list_tests.rs** - Added 6 new tests for enumif support:
   - `test_comma_list_with_enumif_constraint` - basic enumif with comma_list
   - `test_comma_list_with_enumif_constraint_invalid_field` - rejects unauthorized fields
   - `test_comma_list_with_enumif_fuzzy_matching` - supports fuzzy patterns (start:, end:, contain:)
   - `test_comma_list_with_enumif_no_matching_condition` - rejects when no condition matches
   - `test_comma_list_with_enumif_multiple_items_validation` - validates each item with index context

13. **tests/error_handling_parameter_validation_list.rs** - Updated test
   - Fixed test expectation to handle new context format in error messages

### Example: Role-Based Field Access with EnumIf
```json
{
  "conditional_fields": {
    "query": "SELECT ~[fields] FROM users WHERE id = @id",
    "returns": ["name", "email", "age"],
    "args": {
      "fields": {
        "enumif": {
          "role": {
            "admin": ["name", "email", "age"],
            "user": ["name"]
          }
        }
      },
      "role": {"enum": ["admin", "user"]},
      "id": {"type": "integer"}
    }
  }
}
```
With runtime params: `{"fields": ["name", "email"], "role": "admin", "id": 1}`
Admin can select all fields, user can only select name.

All tests passing (28 comma_list tests + all existing tests).
