# 5/17 部課

## TODO
- [x] graphql
- [x] 填表單
- [ ] 練習coursemap

## GraphQL

上次簡單介紹過GraphQL後端了 (想複習的請參考[這裡](https://hackmd.io/Bo7_enSbQPeFZEhcefLr3Q))
不過只介紹了Query，假設我們需要新增(修改)資料，在GraphQL中是使用 Mutation 這個方法

可以做個簡單對照：
GET <--> Query
POST <--> Mutation

我們將實作三個功能：
**Query**
books: 把所有books找出來

**Mutation**
CreateBook: 新增一本書
DeleteBook: 刪除一本書

以下為範例的程式碼：

mkdir graphql
cd graphql
npm init -y

mkdir backend
cd backend
npm init -y
npm pkg set type="module"
npm install @apollo/server graphql nodemon

# 下列的程式碼都要放在 backend 資料夾裡

定義Types

In `schema.gql`:

type Book {
  id: ID!
  title: String!
  author: String!
  publishDate: String!
}

type Query {
  books: [Book!]!
}

type Mutation {
  createBook(title: String!, author: String!, publishDate: String!): Book!
  deleteBook(id: ID!): Book!
}

創建一些local資料

In `data/books.js`:

export let books = [
  {
    id: 1,
    title: "The Great Gatsby",
    author: "F. Scott Fitzgerald",
    publishDate: "1925-04-10"
  },
  {
    id: 2,
    title: "To Kill a Mockingbird",
    author: "Harper Lee",
    publishDate: "1960-07-11"
  }
];

定義resolvers

In `resolvers/Query.js`:

import { books } from '../data/books.js';

export const Query = {
  books: () => books
};

In `resolvers/Mutation.js`:

import { books } from '../data/books.js';

export const Mutation = {
  createBook: (_, { title, author, publishDate }) => {
    const newBook = {
      id: books.length + 1,
      title,
      author,
      publishDate
    };
    books.push(newBook);
    return newBook;
  },
  deleteBook: (_, { id }) => {
    const bookIndex = books.findIndex(book => book.id === parseInt(id));
    if (bookIndex === -1) return null;
    const [deletedBook] = books.splice(bookIndex, 1);
    return deletedBook;
  }
};

把上述function合併至index.js中

In `index.js`:

import { ApolloServer } from "@apollo/server";
import { startStandaloneServer } from "@apollo/server/standalone";
import { readFileSync } from "fs";
import { Query } from "./resolvers/Query.js";
import { Mutation } from "./resolvers/Mutation.js";

// Read type definitions from schema.gql
const typeDefs = readFileSync("./src/schema.gql", "utf8");

// Resolvers
const resolvers = {
    Query,
    Mutation,
};

// Create Apollo Server
const server = new ApolloServer({ typeDefs, resolvers });

// Start the server
const { url } = await startStandaloneServer(server, {
    listen: { port: 4000 },
});

console.log(`🚀  Server ready at: ${url}`);

一樣，要能夠hot reload的話，請安裝nodemon，並且在指令的地方，把node 換成 nodemon。

graphql
├── backend
│   ├── node_modules/
│   ├── package-lock.json
│   ├── package.json
│   └── src
│       ├── data
│       │   └── books.js
│       ├── index.js
│       ├── resolvers
│       │   ├── Mutation.js
│       │   └── Query.js
│       └── schema.gql
└── package.json

後端架設好之後，我們就來用前端操作吧！

# 回到 graphql
cd ..
npm create vite@latest

√ Project name: ... frontend
√ Select a framework: » React
√ Select a variant: » JavaScript

cd frontend
npm install
npm install @apollo/client graphql

創建Apollo Provider:

In `src/ApolloProvider.jsx`:

import React from "react";
import { ApolloClient, InMemoryCache, ApolloProvider as Provider } from "@apollo/client";

const client = new ApolloClient({
    uri: "http://localhost:4000", // Replace with your GraphQL server URL
    cache: new InMemoryCache(),
});

const ApolloProvider = ({ children }) => {
    return <Provider client={client}>{children}</Provider>;
};

export default ApolloProvider;

在App.jsx中定義剩餘介面

In `App.jsx`:

import React, { useState } from "react";
import { gql, useQuery, useMutation } from "@apollo/client";
import ApolloProvider from "./ApolloProvider";
import "./App.css";

const GET_BOOKS = gql`
    query GetBooks {
        books {
            id
            title
            author
            publishDate
        }
    }
`;

const CREATE_BOOK = gql`
    mutation CreateBook($title: String!, $author: String!, $publishDate: String!) {
        createBook(title: $title, author: $author, publishDate: $publishDate) {
            id
            title
            author
            publishDate
        }
    }
`;

const DELETE_BOOK = gql`
    mutation DeleteBook($id: ID!) {
        deleteBook(id: $id) {
            id
        }
    }
`;

const App = () => {
    const { loading, error, data, refetch } = useQuery(GET_BOOKS);
    const [createBook] = useMutation(CREATE_BOOK);
    const [deleteBook] = useMutation(DELETE_BOOK);

    const [title, setTitle] = useState("");
    const [author, setAuthor] = useState("");
    const [publishDate, setPublishDate] = useState("");

    const handleAddBook = async () => {
        await createBook({
            variables: { title, author, publishDate },
        });
        refetch();
        setTitle("");
        setAuthor("");
        setPublishDate("");
    };

    const handleDeleteBook = async (id) => {
        await deleteBook({ variables: { id } });
        refetch();
    };

    if (loading) return <p>Loading...</p>;
    if (error) return <p>Error: {error.message}</p>;

    return (
        <div className="container">
            <h1>Books</h1>
            <ul>
                {data.books.map((book) => (
                    <li key={book.id}>
                        {book.title} by {book.author} (Published: {book.publishDate})
                        <button onClick={() => handleDeleteBook(book.id)}>Delete</button>
                    </li>
                ))}
            </ul>
            <h2>Add a New Book</h2>
            <div className="form">
                <input
                    type="text"
                    placeholder="Title"
                    value={title}
                    onChange={(e) => setTitle(e.target.value)}
                />
                <input
                    type="text"
                    placeholder="Author"
                    value={author}
                    onChange={(e) => setAuthor(e.target.value)}
                />
                <input
                    type="text"
                    placeholder="Publish Date"
                    value={publishDate}
                    onChange={(e) => setPublishDate(e.target.value)}
                />
                <button onClick={handleAddBook}>Add Book</button>
            </div>
        </div>
    );
};

const WrappedApp = () => (
    <ApolloProvider>
        <App />
    </ApolloProvider>
);

export default WrappedApp;

引入 App.css

In `src/App.css`:

body {
    font-family: Arial, sans-serif;
    background-color: #f0f0f0;
    margin: 0;
    padding: 0;
}

.container {
    max-width: 800px;
    margin: 0 auto;
    padding: 20px;
    background-color: #ffffff;
    border-radius: 8px;
    box-shadow: 0 0 10px rgba(0, 0, 0, 0.1);
}

h1 {
    text-align: center;
    color: #333;
}

ul {
    list-style-type: none;
    padding: 0;
}

li {
    background-color: #fafafa;
    margin: 10px 0;
    padding: 10px;
    border: 1px solid #ddd;
    border-radius: 4px;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

button {
    background-color: #ff4d4d;
    border: none;
    color: white;
    padding: 5px 10px;
    border-radius: 4px;
    cursor: pointer;
}

button:hover {
    background-color: #ff3333;
}

.form {
    display: flex;
    flex-direction: column;
    gap: 10px;
    margin-top: 20px;
}

.form input {
    padding: 10px;
    border: 1px solid #ddd;
    border-radius: 4px;
}

.form button {
    background-color: #4caf50;
    border: none;
    color: white;
    padding: 10px;
    border-radius: 4px;
    cursor: pointer;
}

.form button:hover {
    background-color: #45a049;
}

最後，把index.css這個檔案刪掉，並且在`index.js`的地方也把 `import "./index.css"` 拿掉

再來就是跑`npm run dev` 就可以啟動前端了！(但是後端要跑起來，前端才會顯示資料)

subscription: 訂閱，就像訂閱youtube頻道，當該youtuber發佈影片時，你會收到他發新片的「通知」
而一個block假如也有訂閱某些事件的時候(例如剛剛的createbook)，books的陣列一更新，那個block也會馬上收到相關的通知。這裡是用`refetch()` 的方法來重新執行Query以獲取最新的資料，對於固定頻率更新資料或是經過mutation的操作較為適用。

## 練習操作 coursemap

### 使用 coursemap
1. 把 [Coursemap](https://github.com/NTUEEInfoDep/NTUEECourseMap) 的 repo clone 下來

(HTTPS 也可以，用SSH需要設定key，請參照 [Generate a new SSH key](https://docs.github.com/en/authentication/connecting-to-github-with-ssh/generating-a-new-ssh-key-and-adding-it-to-the-ssh-agent))

cd your-target-directory

# git clone [put the copied url here]
git clone https://github.com/NTUEEInfoDep/NTUEECourseMap.git

2. 進入coursemap 資料夾裡，安裝專案需要的套件

cd NTUEECourseMap

# yarn 的速度較 npm 快不少，因此使用 yarn 安裝跟執行
# 使用 yarn
yarn install

# 啟動 coursemap (下列兩種都可以)
yarn run dev
# 或
yarn start

接著，前往 http://localhost:8000/ ，看到畫面就成功囉！

### 使用系學會網站
目前還有一些設定沒有完成，之後有弄好再更新
(demo 連結在上方)
[系學會網站](https://eesa.ntuee.org/) (目前本地跑不動)

### 實習地圖
未定

styled-component
https://styled-components.com/
MUI
tailwind