javascript - Sequelize : Changing the nested data structure

Question

我想更改orm查询返回的数据结构。总共有四张 table 。 product,category是多对多关系，有一个product_category表作为桥梁，一共四张表，包括department 表。关联关系如下:

// product
product.belongsToMany(models.category, {
      through: 'product_category',
      foreignKey: 'product_id'
});

// product_category
product_category.belongsTo(models.product, {
      foreignKey: 'product_id'
});
product_category.belongsTo(models.category, {
      foreignKey: 'category_id'
});

// category
category.belongsToMany(models.product, {
      through: 'product_category',
      foreignKey: 'category_id'
});
category.belongsTo(models.department, {
      foreignKey: 'department_id'
});

// department
department.hasMany(models.category, {
      foreignKey: 'department_id'
});

通过上面的表结构，得到如下查询，获取department_id对应的产品:

const query = await product.findOne({
   where: { product_id: id },
   include: {
     model: category,
     attributes: ['category_id', ['name', 'category_name']],
     include: {
       model: department,
       attributes: ['department_id', ['name', 'department_name']]
     }
   },
   attributes: []
});

const data = query.categories;

生成的json数据如下:

"data": [
    {
        "category_id": 1,
        "category_name": "French",
        "department": {
            "department_id": 1,
            "department_name": "Regional"
        },
        "product_category": {
            "product_id": 1,
            "category_id": 1
        }
    }
]

我想把上面的数据做成如下:

"data": [
    {
         "category_id": 1,
         "category_name": "French",
         "department_id": 1,
         "department_name": "Regional"
    }
]

为了像上面那样处理数据，有两种方法:修改基于sql的orm查询和在javascript中处理product值。 不过由于我是用orm学sql的，所以不知道第一种方法，所以决定用第二种方法。

---

第一次尝试

我做了两次尝试。请注意，该框架使用 koa.js。第一条如下:

const query = await product.findOne({
  where: { product_id: id },
  include: {
    model: category,
    attributes: ['category_id', ['name', 'category_name']],
    include: {
      model: department,
      attributes: ['department_id', ['name', 'department_name']]
    }
  },
  attributes: []
});

const data = query.categories.map(
      ({ category_id, category_name, department }) => ({
        category_id,
        category_name,
        department_id: department.department_id,
        department_name: department.department_name
      })
    );

ctx.body = data;

正文如下:

"data": [
    {
        "category_id": 1,
        "department_id": 1
    }
]

..??有些奇怪，所以我稍微改变了返回值:

({ category_id, category_name, department }) => ({
        // category_id,
        // category_name,
        department_id: department.department_id,
        department_name: department.department_name
      })

输出的json值是:

"data": [
    {
        "department_id": 1
    }
]

相反，您注释了department_id、department_name:

({ category_id, category_name, department }) => ({
        category_id,
        category_name,
        // department_id: department.department_id,
        // department_name: department.department_name
      })

生成的 json 值为:

"data": [
    {
        "category_id": 1
    }
]

我无法以任何其他方式做到这一点。

第二次尝试

await product
.findOne({
  where: { product_id: id },
  include: {
    model: category,
    attributes: ['category_id', ['name', 'category_name']],
    include: {
      model: department,
      attributes: ['department_id', ['name', 'department_name']]
    }
  },
  attributes: []
})
.then(query => {
  const data = query.categories.map(
    ({ category_id, category_name, department }) => ({
      category_id,
      category_name,
      department_id: department.department_id,
      department_name: department.department_name
    })
  );

  ctx.body = data;
});

两种方法的结果相同，所以我不知道该怎么办。

---

所以我将变量映射到带有 json 数据的嵌套数组。我得到了我想要的结果:

const data = {
  categories: [
    {
      category_id: 1,
      category_name: 'French',
      department: { department_id: 1, department_name: 'Regional' },
      product_category: { product_id: 1, category_id: 1 }
    }
  ]
};

const product = data.categories.map(
  ({ category_id, category_name, department }) => ({
    category_id,
    category_name,
    department_id: department.department_id,
    department_name: department.department_name
  })
);

console.log(product);

// [ { category_id: 1,
//    category_name: 'French',
//    department_id: 1,
//    department_name: 'Regional' } ]

所以我很困惑。如何处理来自后续查询的数据？我非常感谢您的帮助。

如果解决问题的方法是错误的或者您需要模型架构，请告诉我。

Answer 1

我以一种简单的方式实现了它。看起来就像一个完整的胃。如果另一个人能将最佳方法纳入答案，那就太好了。

const getProduct = () => {
  const a = query.categories[0];
  const b = a.get({ plain: true });
  const { category_id, category_name } = b;
  const { department_id, department_name } = b.department;

  return {
    category_id,
    category_name,
    department_id,
    department_name
  };
};

ctx.body = getProduct();

Json数据输出:

"product": {
    "category_id": 1,
    "category_name": "French",
    "department_id": 1,
    "department_name": "Regional"
}

---

如果运行 console.log ()， Sequelize 查询将像 dataValues: {}, (...) 一样打印。如果您这样做，您将无法处理您的数据。因此，处理包含查询的变量之后的数据是关键点，如下所示:

data.get ({plain: true})