javascript - 将 knexnest 调用拉出到其自己的文件中以防止重复

Question

我使用 knexnest 的方式如下:

const customerProducts = knex.select([
  'CustomerProduct.id AS _id',
  'CustomerProduct.price AS _price',
  'CustomerProduct.active AS _active',
  'CustomerProduct.customer_id AS _customerId',
  'CustomerProduct.product_id AS _productId',
  'customer.id AS _customer_id',
  'customer.name AS _customer_name',
])
  .from('customer_products AS CustomerProduct')
  .innerJoin(
    'customers AS customer',
    'CustomerProduct.customer_id',
    'customer.id',
  )
  .where(whereClause);

const result = knexnest(customerProducts).then(data => data);
  return result;

我可能会创建几个其他查询，然后使用 knexnest 创建嵌套模型。有什么办法可以拉knexnest(customerProducts).then(data => data);到另一个文件中，这样我就可以调用它，而不是在每个查询中添加该行，并且还必须将 knexnest 导入到每个文件中？

Answer 1

要实现您想要实现的目标，最简单的方法是导出一个返回由 knexnest 生成的 Promise 的函数。然后，在主文件中导入该函数并调用它。您可以使用 async/await 语法糖或 .then。在整个应用程序中使用一个 knex 连接对象来利用 knex 的连接池非常重要。因此，我们必须将其传递到您的函数中，以便其他文件可以访问已建立的连接对象。

文件 1

const Knex = require('knex');

// import the function getCustomerProducts using destructuring 
const { getCustomerProducts } = require('<File 2's Path>');

// initialize knex & set up knex database connection
const knex = Knex({
  client: 'postgres',
  connection: process.env.DATABASE_URL
});

// pseudo-code - note: await can only be called within an async function
// pass knex connection object into function to leverage knex's connection pooling
const products = await getCustomerProducts(knex);

文件2

const knexnest = require('knexnest');

const getCustomerProducts = knex => {

  const customerProducts = knex.select([
      'CustomerProduct.id AS _id',
      'CustomerProduct.price AS _price',
      'CustomerProduct.active AS _active',
      'CustomerProduct.customer_id AS _customerId',
      'CustomerProduct.product_id AS _productId',
      'customer.id AS _customer_id',
      'customer.name AS _customer_name',
    ])
    .from('customer_products AS CustomerProduct')
    .innerJoin(
      'customers AS customer',
      'CustomerProduct.customer_id',
      'customer.id',
    )
    .where(whereClause);

  return knexnest(customerProducts);
};

// named export of the function getCustomerProducts
module.exports.getCustomerProducts = getCustomerProducts;