SequelizeEagerLoadingError，无法通过包含获取数据答案

【问题标题】：SequelizeEagerLoadingError, can't get data with includeSequelizeEagerLoadingError，无法通过包含获取数据
【发布时间】：2018-10-15 20:22:23
【问题描述】：

我使用 Sequelize.js 向数据库发出请求。我在两个表之间有一个多对多的关系，我制作了第三个连接表。这是我的三张桌子。 polit_in_article 是联结表。

politician.js：

module.exports = (sequelize, DataTypes) => {
    const Politician = sequelize.define('politician', {
        ...
    });

    Politician.associate = (models) => {
        Politician.hasMany(models.Polit_in_article, {
            foreignKey: 'politicianId',
            as: 'polit_in_articles',
        });
    };

    return Politician;
};

article.js：

module.exports = (sequelize, DataTypes) => {
    const Article = sequelize.define('article', {
        ...
    });

    Article.associate = (models) => {
        Article.hasMany(models.Politician, {
            foreignKey: 'articleId',
            as: 'polit_in_articles'
        });
    };
    return Article;
};

polit_in_article.js：

module.exports = (sequelize, DataTypes) => {
    const Polit_in_article = sequelize.define('polit_in_article', {
        times_mentioned: DataTypes.INTEGER,
    });
    Polit_in_article.associate = (models) => {
        Polit_in_article.belongsTo(models.Article, {
            // foreignKey: 'articleId',
            as: 'articles',
        });
        Polit_in_article.belongsTo(models.Politician, {
            // foreignKey: 'politicianId',
            as: 'politicians',
        });
    };

    return Polit_in_article;
};

这是我的控制器（不确定这是否是正确的调用方式）：

const Sequelize = require('sequelize');

const Article = require('../models').Article;
const Politician = require('../models').Politician;
const Polit_in_article = require('../models').Polit_in_article;

const Op = Sequelize.Op;

module.exports = {
    getAllArticlesOfPolitician(req) {
        return Article
            .findAll({
                include: [{
                    model: Polit_in_article,
                    include: [{
                        model: Politician,
                        where: {
                            lastname: req.query.politicianLastName,
                        }
                    }],
                }],
            }).then(response => response)
            // .catch(err => err);
    }
};

我得到一个错误SequelizeEagerLoadingError: polit_in_article is not associated to article。可能我错过了一些东西，但我真的不知道在这里做什么。我试图使文章表具有关联 as: 'polit_in_articles'，直到我需要将政治家表也包括到查询中。

【问题讨论】：

标签： javascript node.js express sequelize.js

【解决方案1】：

您需要在关联中使用through 关键字。 Articles 将具有 politicians through Polit_in_article 模型，但是由于您只是在其上使用主键，您可以让它被推断并省略 polit_in_article.js 并使用字符串来命名表。

Politician.associate = (models) => {
  Politician.hasMany(models.Article, {
    foreignKey: 'politicianId',
    through: 'polit_in_article',
    as: 'articles',
  });
};

Article.associate = (models) => {
  Article.hasMany(models.Politician, {
    foreignKey: 'articleId',
    through: 'polit_in_article',
    as: 'politicians',
  });
};

现在您可以通过指定as 和through 来查询连接表。

getAllArticlesOfPolitician(req) {
  return Article.findAll({
    include: [{
      model: Politician,
      as: 'politicians',
      through: 'polit_in_article',
      where: {
        lastname: req.query.politicianLastName,
      },
    }],
  })
  .then(response => response)
  .catch(err => err);
}

【讨论】：

【解决方案2】：

我只需要在 article.js 中修复关联，我与政治家而不是连接表建立关联：

module.exports = (sequelize, DataTypes) => {

    const Article = sequelize.define('article', {
         ...
    });

    Article.associate = (models) => {
        Article.hasMany(models.Polit_in_article, {
            foreignKey: 'articleId',
            as: 'polit_in_articles'
        });
    };
    return Article;
};

【讨论】：