# Elixir Guidelines

> Elixir 开发指南 — 函数式编程、管道操作、模式匹配。Use when developing Elixir applications, functional programming, pipe operator.

- Skill: `liaosw97/elixir-guidelines` (Agent Skill, multi-file: 2 files)
- Install (CLI): `npx skillmds@latest add liaosw97/elixir-guidelines`
- Raw SKILL.md: https://api.skillmd.com/api/skills/liaosw97/elixir-guidelines/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: liaosw97 (https://skillmd.com/u/liaosw97)
- Updated: 2026-09-22
- Page: https://skillmd.com/skills/liaosw97/elixir-guidelines

---


## 核心原则
- 编写代码前仔细考虑所有因素和需求
- 使用函数式编程范式
- 利用管道操作符组合函数
- 使用模式匹配处理不同情况
- 遵循 Elixir 编码规范

## 技术栈
- **语言**：Elixir
- **框架**：Phoenix
- **数据库**：PostgreSQL + Ecto
- **实时**：Phoenix LiveView / Channels
- **容器**：Docker
- **前端**：Tailwind CSS
- **测试**：ExUnit
- **安全**：Sobelow
- **代码质量**：Credo

## 最佳实践
### 项目结构

```
lib/
├── my_app/              # 业务逻辑
│   ├── accounts/        # 上下文模块
│   │   ├── user.ex      # Schema
│   │   └── accounts.ex  # 上下文 API
│   └── application.ex
├── my_app_web/          # Web 层
│   ├── controllers/
│   ├── live/
│   ├── components/
│   └── router.ex
└── my_app_web.ex
```

### Ecto Schema

```elixir
defmodule MyApp.Accounts.User do
  use Ecto.Schema
  import Ecto.Changeset

  schema "users" do
    field :name, :string
    field :email, :string
    field :role, Ecto.Enum, values: [:admin, :user]

    timestamps()
  end

  def changeset(user, attrs) do
    user
    |> cast(attrs, [:name, :email, :role])
    |> validate_required([:name, :email])
    |> validate_format(:email, ~r/@/)
    |> unique_constraint(:email)
  end
end
```

### 上下文模块

```elixir
defmodule MyApp.Accounts do
  import Ecto.Query, warn: false
  alias MyApp.Repo
  alias MyApp.Accounts.User

  def list_users do
    Repo.all(User)
  end

  def get_user!(id), do: Repo.get!(User, id)

  def create_user(attrs \\ %{}) do
    %User{}
    |> User.changeset(attrs)
    |> Repo.insert()
  end
end
```

### LiveView

```elixir
defmodule MyAppWeb.UserLive do
  use MyAppWeb, :live_view

  def mount(_params, _session, socket) do
    {:ok, assign(socket, users: Accounts.list_users())}
  end

  def handle_event("delete_user", %{"id" => id}, socket) do
    user = Accounts.get_user!(id)
    {:ok, _} = Accounts.delete_user(user)
    {:noreply, assign(socket, users: Accounts.list_users())}
  end
end
```

## 关键约定
1. **提交消息规范**
   ```
   <类型>[可选范围]: <描述>

   类型：fix, feat, build, chore, ci, docs, perf, refactor, style, test
   描述：用现在时态简要总结更改
   ```

2. **管道操作符**
   ```elixir
   user
   |> User.changeset(attrs)
   |> Repo.insert()
   ```

3. **模式匹配**
   ```elixir
   def handle_event({:ok, user}, state) do
     # 处理成功
   end

   def handle_event({:error, changeset}, state) do
     # 处理错误
   end
   ```

4. **代码质量工具**
   - Sobelow：安全扫描
   - Credo：代码质量检查
   - ExCoveralls：测试覆盖率

## 安全实践
- 使用 Sobelow 进行安全审计
- 验证所有用户输入
- 使用 CSRF 保护
- 防止 SQL 注入（使用 Ecto）

## 测试规范
```elixir
defmodule MyApp.AccountsTest do
  use MyApp.DataCase

  test "create_user/1 with valid data creates a user" do
    attrs = %{name: "John", email: "john@example.com"}
    assert {:ok, user} = Accounts.create_user(attrs)
    assert user.name == "John"
  end
end
```