node.js - Sequelize 基于关联的查找

Question

我将如何使用 Sequelize 查找关系中的列满足条件的所有人？

例如，查找作者姓氏为“Hitchcock”的所有书籍。book 模式包含与 Author 表的 hasOne 关系。

编辑：我了解如何使用原始 SQL 查询来完成此操作，但正在寻找另一种方法

Answer 1

这是一个工作示例，说明如何使用 Sequelize 以具有特定姓氏的方式获取所有Books内容Author。它看起来比实际复杂一些，因为我正在定义模型、关联它们、与数据库同步（以创建它们的表），然后在这些新表中创建虚拟数据。查找findAll代码中间的 ，具体查看您所追求的内容。

    module.exports = function(sequelize, DataTypes) {

    var Author = sequelize.define('Author', {

        id: {
            type: DataTypes.INTEGER,
            allowNull: false,
            autoIncrement: true,
            primaryKey: true
        },
        firstName: {
            type: DataTypes.STRING
        },
        lastName: {
            type: DataTypes.STRING
        }

    })

    var Book = sequelize.define('Book', {

        id: {
            type: DataTypes.INTEGER,
            allowNull: false,
            autoIncrement: true,
            primaryKey: true
        },
        title: {
            type: DataTypes.STRING
        }

    })

    var firstAuthor;
    var secondAuthor;

    Author.hasMany(Book)
    Book.belongsTo(Author)

    Author.sync({ force: true })
        .then(function() {
            return Book.sync({ force: true });
        })
        .then(function() {
            return Author.create({firstName: 'Test', lastName: 'Testerson'});
        })
        .then(function(author1) {
            firstAuthor=author1;
            return Author.create({firstName: 'The Invisible', lastName: 'Hand'});
        })
        .then(function(author2) {
            secondAuthor=author2
            return Book.create({AuthorId: firstAuthor.id, title: 'A simple book'});
        })
        .then(function() {
            return Book.create({AuthorId: firstAuthor.id, title: 'Another book'});
        })
        .then(function() {
            return Book.create({AuthorId: secondAuthor.id, title: 'Some other book'});
        })
        .then(function() {
            // This is the part you're after.
            return Book.findAll({
                where: {
                   'Authors.lastName': 'Testerson'
                },
                include: [
                    {model: Author, as: Author.tableName}
                ]
            });
        })
        .then(function(books) { 
            console.log('There are ' + books.length + ' books by Test Testerson')
        });
  }

Answer 2

在最新版本的 Sequilize (5.9.0) 中，@c.hill 提出的方法不起作用。

现在您需要执行以下操作：

return Book.findAll({
    where: {
        '$Authors.lastName$': 'Testerson'
    },
    include: [
        {model: Author, as: Author.tableName}
    ]
});

Answer 3

对于文档！

检查急切加载部分

https://sequelize.org/master/manual/eager-loading.html

对于以上答案！您可以在以下标题的文档中找到它

顶层复杂的 where 子句

从文档：

为了获得涉及嵌套列的顶级 WHERE 子句，Sequelize 提供了一种引用嵌套列的方法：'$nested.column$' 语法。

例如，它可用于将包含模型中的 where 条件从 ON 条件移动到顶级 WHERE 子句。

User.findAll({
  where: {
    '$Instruments.size$': { [Op.ne]: 'small' }
  },
  include: [{
    model: Tool,
    as: 'Instruments'
  }]
});

生成的 SQL：

SELECT
  `user`.`id`,
  `user`.`name`,
  `Instruments`.`id` AS `Instruments.id`,
  `Instruments`.`name` AS `Instruments.name`,
  `Instruments`.`size` AS `Instruments.size`,
  `Instruments`.`userId` AS `Instruments.userId`
FROM `users` AS `user`
LEFT OUTER JOIN `tools` AS `Instruments` ON
  `user`.`id` = `Instruments`.`userId`
WHERE `Instruments`.`size` != 'small';

为了更好地理解内部 where 选项（在 include 中使用）、带和不带 required 选项以及使用 $nested.column$ 语法的顶级 where 之间的所有差异，下面我们为您提供了四个示例：

// Inner where, with default `required: true`
await User.findAll({
  include: {
    model: Tool,
    as: 'Instruments',
    where: {
      size: { [Op.ne]: 'small' }
    }
  }
});

// Inner where, `required: false`
await User.findAll({
  include: {
    model: Tool,
    as: 'Instruments',
    where: {
      size: { [Op.ne]: 'small' }
    },
    required: false
  }
});

// Top-level where, with default `required: false`
await User.findAll({
  where: {
    '$Instruments.size$': { [Op.ne]: 'small' }
  },
  include: {
    model: Tool,
    as: 'Instruments'
  }
});

// Top-level where, `required: true`
await User.findAll({
  where: {
    '$Instruments.size$': { [Op.ne]: 'small' }
  },
  include: {
    model: Tool,
    as: 'Instruments',
    required: true
  }
});

生成的 SQL，按顺序：

-- Inner where, with default `required: true`
SELECT [...] FROM `users` AS `user`
INNER JOIN `tools` AS `Instruments` ON
  `user`.`id` = `Instruments`.`userId`
  AND `Instruments`.`size` != 'small';

-- Inner where, `required: false`
SELECT [...] FROM `users` AS `user`
LEFT OUTER JOIN `tools` AS `Instruments` ON
  `user`.`id` = `Instruments`.`userId`
  AND `Instruments`.`size` != 'small';

-- Top-level where, with default `required: false`
SELECT [...] FROM `users` AS `user`
LEFT OUTER JOIN `tools` AS `Instruments` ON
  `user`.`id` = `Instruments`.`userId`
WHERE `Instruments`.`size` != 'small';

-- Top-level where, `required: true`
SELECT [...] FROM `users` AS `user`
INNER JOIN `tools` AS `Instruments` ON
  `user`.`id` = `Instruments`.`userId`
WHERE `Instruments`.`size` != 'small';

这让我们很好地了解了join是如何完成的！