Dependency Chain: category -> shop => category in model sequelizejs while defining foreign key

Question

List of Error:

\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

While running this file Model.js

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();

While defining shop model, I got the above errors. foreign key categoryid in shop, I'm not getting the exact reason, what it means by Shop is dependent on itself, dependency cycle.

Answer 1

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

Creates a relation from category -> shop, while the scategory column creates a relation from shop -> category. Because the relation goes both ways, sequelize does not know which table to create first - both tables require the other table to be created first.

You probably need to reverse the relation to:

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

Does a category only relate to a single shop? Otherwise you need Category.hasMany(shop); to enable the same category to be related to several shops.

Furthermore, you don't need to both add a column (scategory) and call association functions - one is enough. This should be sufficient:

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

While removing scategory from the defintion of shop. To enforce that scategory cannot be null, you can do:

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

Answer 2

However, the code above will result in the following error: Cyclic dependency found. 'Document' is dependent of itself. Dependency Chain: Document -> Version => Document. In order to alleviate that, we can pass constraints: false to one of the associations: Document.hasMany(Version) Document.belongsTo(Version, { as: 'Current', foreignKey: 'current_version_id', constraints: false})

http://docs.sequelizejs.com/en/latest/docs/associations/