.map 函数中的异步验证

Question

我正在使用 Node JS、Sequelize 和 Postgres 数据库开发应用程序的后端。

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组织 ID 通过数组传递到后端，我正在尝试进行检查以确保传递的 ID 存在。

到目前为止我所做的是：

const { organizations } = req.body;

const organizationsArray = organizations.map(async (organization) => {

  const organizationExists = await Organization.findByPk(organization);

  if (!organizationExists) {

    return res

      .status(400)

      .json({ error: `Organization ${organization} does not exists!` });

  }

  return {

    course_id: id,

    organization_id: organization,

  };

});

await CoursesOrganizations.bulkCreate(organizationsArray);

Answer 1

正在Array.map()返回一个承诺数组，您可以使用Promise.all(). 在地图内部，您应该使用throw new Error()break out of map - 将引发此错误Promise.all()，然后您可以捕获它并将错误返回给客户端（或吞下它等）。这是您的模式的更正版本，解决了 Promise 结果。const { organizations } = req.body;try {  // use Promise.all to resolve the promises returned by the async callback function  const organizationsArray = await Promise.all(    // this will return an array of promises    organizations.map(async (organization) => {      const organizationExists = await Organization.findByPk(organization, {         attributes: ['id'], // we only need the ID        raw: true, // don't need Instances      });      if (!organizationExists) {        // don't send response inside the map, throw an Error to break out        throw new Error(`Organization ${organization} does not exists!`);      }      // it does exist so return/resolve the value for the promise      return {        course_id: id,        organization_id: organization,      };    })  );  // if we get here there were no errors, create the records  await CoursesOrganizations.bulkCreate(organizationsArray);  // return a success to the client  return res.json({ success: true });} catch (err) {  // there was an error, return it to the client  return res.status(400).json({ error: err.message }); }Organizations这是一个重构版本，通过在一个查询中获取所有内容然后进行检查/创建插入，速度会更快一些Course。const { Op } = Sequelize;const { organizations } = req.body;try {  // get all Organization matches for the IDs  const organizationsArray = await Organization.findAll({    attributes: ['id'], // we only need the ID    where: {      id: {        [Op.in]: organizations, // WHERE id IN (organizations)       }    },    raw: true, // no need to create Instances  });  // create an array of the IDs we found  const foundIds = organizationsArray.map((org) => org.id);  // check to see if any of the IDs are missing from the results  if (foundIds.length !== organizations.length) {    // Use Array.reduce() to figure out which IDs are missing from the results    const missingIds = organizations.reduce((missingIds, orgId) => {      if (!foundIds.includes(orgId)){        missingIds.push(orgId);      }      return missingIds;    }, []); // initialized to empty array    throw new Error(`Unable to find Organization for: ${missingIds.join(', ')}`);  }  // now create an array of courses to create using the foundIds  const courses = foundIds.map((orgId) => {    return {      course_id: id,      organization_id: orgId,    };   });  // if we get here there were no errors, create the records  await CoursesOrganizations.bulkCreate(courses);  // return a success to the client  return res.json({ success: true });} catch (err) {  // there was an error, return it to the client  return res.status(400).json({ error: err.message }); }

Answer 2

如果你有一个 ID 数组并且你想检查它们是否存在你应该使用 (in) 运算符，这使得你只访问数据库一次并一次获取所有记录（而不是获取它们一个一个循环），在你得到这些记录后，你可以检查它们的长度以确定它们是否都存在。const { Op } = require("sequelize");let foundOrgs = await Organization.findAll({  where: {    id: {      [Op.in]: organizationsArray,    }  }});