Feathers-Sequelize：belongsToMany或belongsTo…创建关联

Question

使用羽毛+ sequelize（newbee），我想为Tag模型建立一个多对多关系，其中Tag可以有很多父母和很多孩子。

    tags.belongsToMany(tags, {
      as: 'parents',
      through: tags_tags,
      foreignKey: 'parentId',
      otherKey: 'id',
      onDelete: 'RESTRICT',
      onUpdate: 'CASCADE',
    });

    tags.belongsToMany(tags, {
      as: 'children',
      through: tags_tags,
      foreignKey: 'id',
      otherKey: 'parentId',
      onDelete: 'CASCADE',
      onUpdate: 'CASCADE',
    });

模型似乎很好，数据库可以很好地建立。

现在，我正在研究如何从羽毛服务中添加关系。真的很沮丧，因为这应该很简单，但是我似乎找不到任何可以帮助我的东西。我错过了明显的东西吗？

app.services.tags
  .create({
    name: 'siteRoot',
  })
  .then(siteRoot => {
    // something like siteRoot.addChild() ?
    // app.services.tags.Model has .children
    // but how can I use it ?
  })

---

在models / tags.model.ts中

// See http://docs.sequelizejs.com/en/latest/docs/models-definition/
// for more of what you can do here.
import { Sequelize, DataTypes, Op } from 'sequelize';
import { Application } from '../declarations';

export default function (app: Application) {
  const sequelizeClient: Sequelize = app.get('sequelizeClient');
  const tags = sequelizeClient.define(
    'tags',
    {
      id: {
        type: DataTypes.INTEGER,
        allowNull: false,
        primaryKey: true,
        autoIncrement: true,
      },
      deleted: {
        type: DataTypes.BOOLEAN,
        allowNull: false,
        defaultValue: false,
      },
      name: {
        type: DataTypes.STRING,
        allowNull: false,
      },
    },
    {
      hooks: {
        beforeCount(options: any) {
          options.raw = true;
        },
      },
      // timestamps: false,
      // tableName: 'tag',
      // underscored: true,
      indexes: [
        {
          fields: ['name'],
        },
    }
  );

  // eslint-disable-next-line no-unused-vars
  (tags as any).associate = function (models: any) {
    // Define associations here
    // See http://docs.sequelizejs.com/en/latest/docs/associations/

    const { tags } = models;

    tags.belongsTo(tags, {
      foreignKey: 'siteBaseTagId',
      as: 'siteBaseTag',
      onDelete: 'RESTRICT',
      onUpdate: 'CASCADE',
    });

    tags.hasMany(tags, {
      foreignKey: 'siteBaseTagId',
      as: 'siteTags',
    });
  };

  return tags;
}

和在models / tags-tags.model.ts中

// See http://docs.sequelizejs.com/en/latest/docs/models-definition/
// for more of what you can do here.
import { Sequelize, DataTypes } from 'sequelize';
import { Application } from '../declarations';

export default function (app: Application) {
  const sequelizeClient: Sequelize = app.get('sequelizeClient');
  const tagsTags = sequelizeClient.define(
    'tags_tags',
    {
      id: {
        type: DataTypes.INTEGER,
        allowNull: false,
        primaryKey: true,
      },
      parentId: {
        type: DataTypes.INTEGER,
        allowNull: false,
        primaryKey: true,
      },
      template: {
        type: DataTypes.STRING,
        allowNull: true,
      },
      url: {
        type: DataTypes.STRING,
        allowNull: true,
      },
    },
    {
      hooks: {
        beforeCount(options: any) {
          options.raw = true;
        },
      },
      timestamps: false,
    }
  );

  // eslint-disable-next-line no-unused-vars
  (tagsTags as any).associate = function (models: any) {
    // Define associations here
    // See http://docs.sequelizejs.com/en/latest/docs/associations/

    const { tags, tags_tags } = models;

    tags.belongsToMany(tags, {
      as: 'parents',
      through: tags_tags,
      foreignKey: 'parentId',
      otherKey: 'id',
      onDelete: 'RESTRICT',
      onUpdate: 'CASCADE',
    });

    tags.belongsToMany(tags, {
      as: 'children',
      through: tags_tags,
      foreignKey: 'id',
      otherKey: 'parentId',
      onDelete: 'CASCADE',
      onUpdate: 'CASCADE',
    });

    tags_tags.belongsTo(tags, {
      foreignKey: 'parentId',
    });
    tags.hasMany(tags_tags, {
      foreignKey: 'parentId',
    });

    tags_tags.belongsTo(tags, {
      foreignKey: 'id',
    });
    tags.hasMany(tags_tags, {
      foreignKey: 'id',
    });
  };

  return tagsTags;
}

Answer 1

belongsToMany是处理羽毛方面最困难的关联之一。限制绝对不在feathers端，而是sequelize如何处理它们。

我对您的问题有点困惑。如果您可以确切说明需要帮助的地方，则希望提供帮助。

旁注：也许您应该将模型重命名为diff。tags|| tags_tags似乎彼此接近，并且//在某些时候可能会造成混淆。平均时间喜欢将您指向该线程，该线程已经活跃了一段时间，因为每个人对belongsToMany关系的处理方式不同。希望您能从中获得一些指导。https://github.com/feathersjs/feathers/issues/852#issuecomment-406413342

如果您只需要M:N，那么我会简单地这样做：

// tag model
tag.associate = models => {
  tag.belongsToMany(models.tag_tag, {
    through: 'parent_child_table', // name this table to your liking.
    foreignKey: 'tag_id'
  });
};

// tag_tag model
tag_tag.associate = models => {
  tag_tag.belongsToMany(models.tag, {
    through: 'parent_child_table', // table name MUST be the same as above
    foreignKey: 'tag_tag_id'
  });
};

上面将创建另一个表parent_child_table，您将在其中跟踪关联。您将必须创建一个单独的服务才能在此表上执行CRUD。这应该可以帮助您入门。