Replace magic string 'public' with named constant

[sgaunet]

Problem

The string literal "public" is used as the default schema in multiple locations throughout main.go, creating a magic string constant that's duplicated and harder to maintain.

Locations:

• Line 146: schema := "public"
• Line 375: schema := "public" (approximately)
• Multiple tool handlers

Issues

1. Duplication: Same literal repeated in multiple places
2. Maintenance: If default changes, must update all locations
3. Unclear intent: Not obvious why "public" is special
4. Error-prone: Easy to typo or use inconsistent casing

Proposed Solution

Option 1: Define Constant in main.go

const (
    // DefaultSchema is the default PostgreSQL schema when none is specified
    DefaultSchema = "public"
)

// Usage in tool handlers
schema := args["schema"].(string)
if schema == "" {
    schema = DefaultSchema
}

Option 2: Define in App Package (Better)

Since this is PostgreSQL-specific knowledge, define it in the app package:

// internal/app/constants.go
package app

const (
    // DefaultSchema is the default PostgreSQL schema used when none is specified.
    // PostgreSQL creates a "public" schema by default in every database.
    DefaultSchema = "public"
)

Then use in main.go:

import "github.com/sgaunet/postgresql-mcp/internal/app"

// In tool handler
schema := args["schema"].(string)
if schema == "" {
    schema = app.DefaultSchema
}

Option 3: Add to App Config

If schema defaults should be configurable:

type AppConfig struct {
    DefaultSchema string
}

func NewWithConfig(client PostgreSQLClient, config AppConfig) *App {
    if config.DefaultSchema == "" {
        config.DefaultSchema = "public"
    }
    return &App{
        client:        client,
        defaultSchema: config.DefaultSchema,
    }
}

Recommended Approach

Use Option 2 (constant in app package) because:

• Keeps PostgreSQL-specific knowledge in the app layer
• Makes the constant reusable across packages
• Documents why "public" is the default
• Simple and doesn't require config changes

Other Magic Strings to Review

Search for other repeated string literals:

# Find repeated string literals
grep -r '"public"' --include="*.go"
grep -r '"postgres"' --include="*.go"
grep -r '"text"' --include="*.go"

Impact

• Severity: TRIVIAL
• Type: Code Quality, Refactoring
• Location: main.go (multiple locations)
• Benefits: Better maintainability, clearer intent

Checklist

• Create constant for default schema name
• Replace all hardcoded "public" strings with constant
• Add documentation explaining why "public" is the default
• Search for other magic strings that should be constants
• Update tests if needed
• Consider making schema default configurable in the future