EagerEye for VS Code

Real-time static analysis for detecting N+1 queries in Rails applications.

Catch N+1 queries before they hit production — right in your editor.

Table of Contents

• Features
• Installation
• Quick Start
• Detected Issues
• Commands
• Extension Settings
• How It Works
• Related
• License

Features

Real-time Analysis — Automatically analyzes Ruby files on save, highlighting potential N+1 issues instantly.

Problem Highlighting — Squiggly underlines show exactly where N+1 queries may occur in your code.

Quick Fixes — One-click fixes for common issues like replacing .pluck(:id) with .select(:id).

Status Bar Integration — See issue count at a glance in your VS Code status bar.

7 Detector Types — Comprehensive detection covering the most common N+1 patterns in Rails applications.

Installation

Prerequisites

Install the EagerEye gem:

gem install eager_eye

Or add to your Gemfile:

gem "eager_eye", group: :development

Install Extension

Option 1: Search for "EagerEye" in VS Code Extensions (Cmd+Shift+X / Ctrl+Shift+X)

Option 2: Install from VS Code Marketplace

Option 3: Command line:

code --install-extension hamzagedikkaya.eager-eye

Quick Start

1. Open a Rails project in VS Code
2. Open any Ruby file (controller, model, serializer, etc.)
3. Save the file — EagerEye automatically analyzes it
4. Issues appear as warnings with squiggly underlines
5. Hover over underlined code to see details and suggestions

Detected Issues

EagerEye detects 7 types of N+1 query patterns:

Quick Fixes

• Auto-fix generic N+1 queries where possible.
• Pluck to Select: Safely converts .pluck(:id) to .select(:id) inside where clauses.
  • Smart Safety: Only fixes safe patterns and ignores small collections (Info severity).

Severity Levels

• Error: Critical N+1 queries (e.g. .all.pluck).
• Warning: Standard N+1 queries.
• Info: Low impact issues or small collections.

Example Detection

# EagerEye will warn about this:
posts.each do |post|
  post.author.name      # ⚠️ N+1 query detected
  post.comments.count   # ⚠️ COUNT query for each post
end

# Suggested fix:
posts.includes(:author, :comments).each do |post|
  post.author.name      # ✓ No additional query
  post.comments.size    # ✓ No additional query
end

Commands

Access commands via Command Palette (Cmd+Shift+P / Ctrl+Shift+P):

Extension Settings

Configure EagerEye in VS Code settings (Cmd+, / Ctrl+,):

Example Configuration

{
  "eagerEye.enable": true,
  "eagerEye.analyzeOnSave": true,
  "eagerEye.excludePatterns": [
    "**/spec/**",
    "**/test/**",
    "**/vendor/**",
    "**/legacy/**"
  ],
  "eagerEye.enabledDetectors": [
    "loop_association",
    "serializer_nesting"
  ]
}

How It Works

EagerEye uses static analysis with AST (Abstract Syntax Tree) parsing to detect potential N+1 query patterns without running your code. This means:

• No test suite required — Works on any Ruby file
• No runtime overhead — Analysis happens at parse time
• Instant feedback — See issues as you code

For comprehensive N+1 detection, use EagerEye alongside runtime tools like Bullet.

Related

• EagerEye Gem — CLI tool and Ruby gem
• RubyGems — Gem installation
• Report Issue — Bug reports and feature requests

License

This extension is available as open source under the terms of the MIT License.

Made with ❤️ for the Rails community