node.js - 依赖链 : category -> shop => category in model sequelizejs while defining foreign key

Question

错误列表:

\Possibly unhandled Error: Cyclic dependency found. 'category' is dependent of itself. Dependency Chain: category -> shop => category
at visit (/home/rashmi/nodejs/node_modules/sequelize/node_modules/toposort-class/toposort.js:74:27)
at /home/rashmi/nodejs/node_modules/sequelize/node_modules/toposort-class/toposort.js:96:25
at Array.forEach (native)
at visit (/home/rashmi/nodejs/node_modules/sequelize/node_modules/toposort-class/toposort.js:95:20)
at /home/rashmi/nodejs/node_modules/sequelize/node_modules/toposort-class/toposort.js:96:25
at Array.forEach (native)
at visit (/home/rashmi/nodejs/node_modules/sequelize/node_modules/toposort-class/toposort.js:95:20)
at Toposort.self.sort (/home/rashmi/nodejs/node_modules/sequelize/node_modules/toposort-class/toposort.js:104:21)
at module.exports.ModelManager.forEachDAO (/home/rashmi/nodejs/node_modules/sequelize/lib/model-manager.js:88:21)
at /home/rashmi/nodejs/node_modules/sequelize/lib/sequelize.js:894:25

在运行这个文件 Model.js 时

var Category=sequelize.define("category",{
    categoryname :{
        type: Sequelize.STRING,
        validate:{isAlpha:true}
    }},
    {
        paranoid: true,
        freezeTableName: true, //modeltable name will be the same as model name
        comment: "I'm Category table!"
    });

var shop=sequelize.define("shop",{
    shopID:{
        type: Sequelize.INTEGER,
        allowNull: false,
        primaryKey: true,
        autoIncrement: true
    },
    title: {
        type: Sequelize.STRING(100),
         allowNull: false,
        validate:{isAlpha: true} 
    },
    shopKeeperName:{
        type: Sequelize.STRING(100),
         allowNull: false,
        validate:{isAlpha: true} 
    },
    mobile :{
        type: Sequelize.CHAR(10),
         allowNull: false
    },
    city :{
        type: Sequelize.INTEGER,
         allowNull: false,
         references: "City",
         referencesKey: "cityId"
    },
    scategory :{
        type: Sequelize.STRING,
        allowNull: false,
        references: "category",
        referencesKey: "Id"
    },
    address :{
        type: Sequelize.TEXT,
        allowNull: false,
        validate:{ isAlphanumeric:true}
    },
    stock :{
        type: Sequelize.INTEGER,
        validate: {isInt: true}
    }
    },
    {
        paranoid: true,
        freezeTableName: true, //modeltable name will be the same as model name
        underscored: true,
        comment: "I'm Shop table!"
    });

state.hasMany(city);
city.belongsTo(state,{foreignKey: 'stateID'});

Agent.hasOne(city);
city.belongsTo(Agent);

Agent.hasOne(state);
state.belongsTo(Agent);

shop.hasOne(Category);
Category.belongsTo(shop);
sequelize.sync();

在定义商店模型时，出现上述错误。 shop 中的外键 categoryid，我没有得到确切的原因，Shop 的意思是依赖于自身，依赖循环。

Answer 1

shop.hasOne(Category);
Category.belongsTo(shop);

从 category -> shop 创建关系，而 scategory 列从 shop -> category 创建关系。因为关系是双向的，所以 sequelize 不知道先创建哪个表 - 两个表都需要先创建另一个表。

您可能需要反转关系到:

shop.belongsTo(Category);
Category.hasOne(shop);

一个类别是否只与一家商店有关？否则，您需要 Category.hasMany(shop); 来使同一类别与多个商店相关。

此外，您不需要既添加列(分类)又调用关联函数—​​—一个就足够了。这应该足够了:

shop.belongsTo(Category, { foreignKey: 'scategory' });

同时从商店的定义中删除 scategory。要强制 scategory 不能为 null，您可以执行以下操作:

Shop.belongsTo(Category, { 
  foreignKey: { 
    allowNull: false, 
    name: 'scategory'
  }
});