rails-debugger

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Rails Debugger

Rails 调试工具

Debugging Process

调试流程

1. Gather Information

1. 收集信息

bash

tail -100 log/development.log
bundle exec rspec --format documentation
bin/rails db:migrate:status

bash

tail -100 log/development.log
bundle exec rspec --format documentation
bin/rails db:migrate:status

2. Analyze Stack Traces

2. 分析堆栈跟踪

Identify the origin:

Find the first line in
```
app/
```
directory
Note the file, line number, and method

Common patterns:

Error	Likely Cause
`NoMethodError: undefined method for nil:NilClass`	Missing association, nil return
`ActiveRecord::RecordNotFound`	ID doesn't exist, scoping issue
`ActiveRecord::RecordInvalid`	Validation failed
`ActionController::ParameterMissing`	Required param not sent
`NameError: uninitialized constant`	Missing require, typo
`LoadError`	File not found, autoload path issue

定位问题来源：

找到
```
app/
```
目录中的第一行报错信息
记录文件、行号和方法

常见错误模式：

错误	可能原因
`NoMethodError: undefined method for nil:NilClass`	关联缺失，返回nil
`ActiveRecord::RecordNotFound`	ID不存在，作用域问题
`ActiveRecord::RecordInvalid`	验证失败
`ActionController::ParameterMissing`	缺少必填参数
`NameError: uninitialized constant`	缺少引用，拼写错误
`LoadError`	文件未找到，自动加载路径问题

3. Check Common Issues

3. 检查常见问题

Database:

bash

bin/rails db:migrate:status
bin/rails db:schema:dump

Dependencies:

bash

bundle check
bundle install

数据库相关：

bash

bin/rails db:migrate:status
bin/rails db:schema:dump

依赖相关：

bash

bundle check
bundle install

4. Isolate the Problem

4. 隔离问题

Reproduce in console:

ruby

user = User.find(123)
user.some_method  # Does it fail here?

Binary search:

Comment out half the code
Does error persist?
Narrow down

在控制台中复现：

ruby

user = User.find(123)
user.some_method  # 此处是否会报错？

二分排查法：

注释掉一半代码
错误是否仍然存在？
逐步缩小范围

5. Check Recent Changes

5. 检查近期变更

bash

git log --oneline -20
git log -p --follow app/models/user.rb
git diff HEAD~5 app/models/user.rb

bash

git log --oneline -20
git log -p --follow app/models/user.rb
git diff HEAD~5 app/models/user.rb

Debugging Techniques

调试技巧

Hypothesis Testing

假设验证法

Form specific, testable theories
Design minimal tests to prove/disprove
Document what you've ruled out

提出具体、可验证的假设
设计最小化测试来证明/推翻假设
记录已排除的可能性

State Inspection

状态检查

ruby

Rails.logger.debug { "DEBUG: user=#{user.inspect}" }
binding.irb  # Pause here (Rails 7+)

ruby

Rails.logger.debug { "DEBUG: user=#{user.inspect}" }
binding.irb  # 在此处暂停（Rails 7+）

Common Rails Issues

常见Rails问题

N+1 Queries

N+1 查询问题

bash

grep "SELECT" log/development.log | sort | uniq -c | sort -rn

Fix:

User.includes(:posts)

bash

grep "SELECT" log/development.log | sort | uniq -c | sort -rn

修复方案：

User.includes(:posts)

Routing Issues

路由问题

bash

bin/rails routes | grep users
bin/rails routes -c users

bash

bin/rails routes | grep users
bin/rails routes -c users

Callback Issues

回调问题

ruby

User._create_callbacks.map(&:filter)
User._save_callbacks.map(&:filter)

ruby

User._create_callbacks.map(&:filter)
User._save_callbacks.map(&:filter)

Bug Report Validation

Bug报告验证

Classification

分类

Status	Meaning
Confirmed Bug	Reproduced with clear deviation
Cannot Reproduce	Unable to reproduce
Not a Bug	Behavior is correct per spec
Data Issue	Problem with specific data

状态	含义
Confirmed Bug	已复现，存在明显偏差
Cannot Reproduce	无法复现
Not a Bug	行为符合规范
Data Issue	特定数据存在问题

Output Format

输出格式

Reproduction Status - Confirmed / Cannot Reproduce / Not a Bug
Root Cause - What's actually wrong (explain why)
Evidence - Specific logs, traces, or code
Fix - Minimal code changes
Prevention - How to avoid similar issues
Verification - Commands/tests to confirm fix

复现状态 - 已确认/无法复现/不是Bug
根本原因 - 实际问题所在（解释为什么会发生）
证据 - 具体日志、堆栈跟踪或代码
修复方案 - 最小化代码变更
预防措施 - 如何避免类似问题
验证方式 - 确认修复的命令/测试