试图了解异步/等待

时间:2020-06-06 02:26:44

标签: javascript asynchronous async-await

我有一个异步函数'query',它“唤醒” pool.query以返回结果。

// db.js

const pool = new pg.Pool({
  connectionString: isProduction ? process.env.DATABASE_URL : connectionString,
  ssl: isProduction,
});

export const query = async ({ text, values }) => {
  const start = Date.now();

  try {
    const results = await pool.query(text, values);
    const duration = Date.now() - start;
    logger.info(`executed query: ${text} duration: ${duration} rows: ${results.rowCount}`);
    return results.rows;
  } catch (e) {
    logger.error(`error: ${e}`);
  }
};

在另一个异步函数getUser()中,我正在“等待”查询函数在返回数据之前完成。


// users.js

export const getUser = async (email) => {
  const text = `
      SELECT (user_id, email) FROM users 
      WHERE email = $1
  `;
  const values = [email];

  try {
    const data = await query({ text, values });
    // ^ vscode says above await is doing nothing
    return data.rows[0];
  } catch (e) {
    logger.error(`error: ${e}`);
  }
};

然后在另一个异步函数中,我正在等待getUser函数


// auth.js

export const SignIn = async (email, password) => {
  const userRecord = await getUser(email);
  if (!userRecord) {
    throw new Error('User not registered');
  }

  logger.silly('Checking password');
  const validPassword = await argon2.verify(userRecord.password, password);
  if (validPassword) {
    logger.silly('Password is valid!');
    logger.silly('Generating JWT');
    const token = await generateToken(userRecord);

    const user = { id: userRecord.id, email: userRecord.email };
    return { user, token };
  } else {
    throw new Error('Invalid Password');
  }
};

在vsCode内部,我收到一条警告“等待对该表达式的类型没有影响”。仅在“等待”查询函数调用时,而不在“等待” getUser函数调用时。我在这里想念什么?

1 个答案:

答案 0 :(得分:0)

query返回什么?如果results.rows是一个承诺,那么这也许可以解释您所看到的。