创建 knex 迁移

Question

我发现有两种方法可以在迁移文件中编写 knex 迁移。

exports.up = function (knex) {
    return knex.schema
      .createTableIfNotExists('foo', function (table) {
        table.increments('id').unique();
        table.string('foo1');
        table.string('foo2');
      })
     .createTableIfNotExists('bar', function (table) {
        table.increments('bar1');
        table.string('bar2').index();
      });

或

exports.up = function (knex) {
    return Promise.all([
      knex.schema.createTableIfNotExists('foo', function (table) {
        table.increments('id').unique();
        table.string('foo1');
        table.string('foo2');
      }),
      knex.schema.createTableIfNotExists('bar', function (table) {
        table.increments('bar1');
        table.string('bar2').index();
      })
    ]);
}

哪一个是正确的做法？

Answer 1

回答者Ricardo Graca at Knex's github issue page

In that case it doesn't make a difference.

You would only use the Promise based one if you require some change in a table before doing another change in another table. For example, if you needed to reference a certain table from another table and none of those tables exist yet, you would create the first table (the one that doesn't depend on anything) in a promise and then when that promise resolved you would create the second table. That way you ensure that dependencies are met.

Answer 2

这是添加 knex 脚本的正确方法，因为承诺是在 knex 中处理查询的首选方式，因为它们允许您 return 来自履行处理程序的值。

exports.up = function (knex) {
return Promise.all([
  knex.schema.createTableIfNotExists('foo', function (table) {
    table.increments('id').unique();
    table.string('foo1');
    table.string('foo2');
  }),
  knex.schema.createTableIfNotExists('bar', function (table) {
    table.increments('bar1');
    table.string('bar2').index();
  })
]);
}

创建 knex 迁移

Creating knex migration

knex.js