前言：昨天大致上對於甚麼GrahpQL，以及預計會用甚麼套件去建置一個API Service，了解基本用法，如何去將資料建立可CRUD(新增(Create)、查詢(Read)、修改(Update)、刪除(Delete))的API Function

今天會利用Node.js這個程式語言分享如何建置我第一支API，以使用者功能登入/註冊為例：

1.import 模組

  const { ApolloServer, gql } = require("apollo-server");

2.定義好資料的結構

const UserModel = mongoose.model("Users", {
  username: String,
  password: String,
});

3.定義程式碼結構

const resolvers = {
    Query: {
       ...
    },
    Mutation: {
        register: async (parent, { username, password }) => {
          const passwordRegex = /^[A-Z].{5,}$/;
          if (!passwordRegex.test(password)) {
            throw new AuthenticationError(
              "Password must start with an uppercase letter and be at least 6 characters long"
            );
          }

          const existingUser = await UserModel.findOne({ username });
          if (existingUser) {
            throw new AuthenticationError("User already exists");
          }

          const hashedPassword = await bcrypt.hash(password, 10);

          const newUser = new UserModel({ username, password: hashedPassword });
          await newUser.save();

          const token = jwt.sign(
            { id: newUser.id, username: newUser.username },
            "your-secret-key",
            {
              expiresIn: "1d",
            }
          );

          return { token, user: { id: newUser.id, username: newUser.username } };
        },
    }
}

const server = new ApolloServer({
  typeDefs,
  resolvers,

  persistedQueries: false,
  playground: true,
});

server.listen({ port: process.env.PORT || 4000 }).then(({ url }) => {
  console.log(`Server is ${url}`);
});

這樣就撰寫好你的第一支API程式囉
接下來執行以下node指令即可在您本機開啟本地伺服器環境！

   npm start

預設會以http:localhost:4000開啟瀏覽器

參考資源

MongoDB
apollographql
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