Sequelize Mysql - Unable to Insert model with one to many relationship - mysql

Question

Design Overview: I've an application with Invoice creation and Inventory management features in it. Let's first understand the database design with 2 entities that we have as below:
Invoices
Items
Now, here I've a M:N relationship between these 2 entities because one invoice can contain multiple items and one item can be included in many such invoices.
So, I've created a 3rd table which we call joining table to associate these entities as shown in the image below,
Problem Statemet: I'm unable to insert model in the child table(invoice_items) using include attribute. Look at the code below to understand what's wrong happening here?
3 Model Classes as below:
1. Invoice:
Note: Providing with fewer attributes to keep it short.
module.exports = (sequelize, DataTypes) => {
const Invoice = sequelize.define('Invoice', {
invoiceId: {
type: DataTypes.INTEGER.UNSIGNED,
allowNull: false,
autoIncrement: true,
primaryKey: true
},
invoiceNumber: {
type: DataTypes.INTEGER(6).UNSIGNED.ZEROFILL,
allowNull: false,
unique: true
},
invoiceTotal: {
type: DataTypes.DECIMAL(9,2),
allowNull: false,
defaultValue: 0.00
},
paymentTotal: {
type: DataTypes.DECIMAL(9,2),
allowNull: false,
defaultValue: 0.00
},
invoiceDate: {
type: DataTypes.DATEONLY,
defaultValue: DataTypes.NOW,
allowNull: false
}
}, {
underscored: true
});
Invoice.associate = function (model) {
Invoice.belongsTo(model.Customer, {
as: 'customer',
foreignKey: {
name: "cust_id",
allowNull: false
}
});
// association with 3rd table
Invoice.hasMany(model.InvoiceItem, {
as: 'invoice_item',
constraints: true,
onDelete: 'NO ACTION',
foreignKey: {
name: "invoice_id",
allowNull: false
}
});
};
return Invoice;
}
2. Item:
Note: Providing with fewer attributes to keep it short.
module.exports = (sequelize, DataTypes) => {
const Item = sequelize.define('Item', {
itemId: {
type: DataTypes.INTEGER.UNSIGNED,
allowNull: false,
autoIncrement: true,
primaryKey: true
},
itemName: {
type: DataTypes.TEXT,
allowNull: false,
defaultValue: ''
},
// this is a opening stock
quantityInStock: {
type: DataTypes.INTEGER.UNSIGNED,
allowNull: false,
defaultValue: 0,
},
unitPrice: {
type: DataTypes.DECIMAL(9,2),
allowNull: false,
defaultValue: 0.00
}
}, {
underscored: true
});
Item.associate = function (model) {
// association with 3rd table
Item.hasMany(model.InvoiceItem, {
as: 'invoice_item', // alias name of a model
constraints: true,
onDelete: 'NO ACTION',
foreignKey: {
name: "item_id",
allowNull: false
}
});
};
return Item;
}
3. Invoice_Item:
Note: Providing with fewer attributes to keep it short.
module.exports = (sequelize, DataTypes) => {
const InvoiceItem = sequelize.define('InvoiceItem', {
invoiceItemId: {
type: DataTypes.INTEGER.UNSIGNED,
allowNull: false,
autoIncrement: true,
primaryKey: true
},
quantity: {
type: DataTypes.INTEGER.UNSIGNED,
allowNull: false,
defaultValue: 0,
},
rate: {
type: DataTypes.DECIMAL(9,2),
allowNull: false,
defaultValue: 0.00
}
}, {
underscored: true
});
InvoiceItem.associate = function(model) {
InvoiceItem.belongsTo(model.Invoice, {
as: 'invoice',
foreignKey: {
name: "invoice_id",
allowNull: false
}
});
InvoiceItem.belongsTo(model.Item, {
as: 'item',
foreignKey: {
name: "item_id",
allowNull: false
}
});
}
return InvoiceItem;
}
Now, I'm using below code to create an invoice with the list of items in it. But, this is not inserting the child records in the joining table(invoice_items). What's wrong here in the code below?
invoice = await Invoice.create({
"invoiceNumber": req.body.invoiceNumber,
"invoiceDate": req.body.invoiceDate,
"invoiceTotal": req.body.invoiceTotal,
"paymentTotal": req.body.paymentTotal,
"cust_id": req.body.customer.custId,
invoice_items: [{
item_id: 1,
quantity: 2,
rate: 300
}]
}, {
include: [{
association: InvoiceItem,
as: 'invoice_item'
}]
});

Answer 1

After trying so many variations, I understand that there was a problem in the association of my model classes. And, below is the way of associating both Invoice and Item model classes for M:N(Many to Many) relationships. I can now update the join table(invoice_items) by inserting the record in it for each invoice we create in the system with the items in it.
Invoice.associate = function (model) {
// association in Invoice model class
Invoice.belongsToMany(model.Item, {
through: 'InvoiceItem',
constraints: true,
onDelete: 'NO ACTION',
foreignKey: {
name: "invoice_id", // foreign key column name in a table invoice_items table
allowNull: false
}
});
};
Item.associate = function (model) {
// association in Item model class
Item.belongsToMany(model.Invoice, {
through: 'InvoiceItem',
constraints: true,
onDelete: 'NO ACTION',
foreignKey: {
name: "item_id", // foreign key column name in a table invoice_items
allowNull: false
}
});
};
Create Invoice with Items in it:
Note: Passing itemId (1) as a parameter in the addItems() method. If you have multiple items in an invoice then you can add forEach loop here to iterate over each item and individually pass the itemId, quantity and rate for an item sold to the customer.
// first create the invoice
invoice = await Invoice.create(invoice);
// Next, add record in the join table
await invoice.addItems([1], {
through: {
quantity: item.quantity,
rate: item.rate
}
});
Database Tables with one Test Result:
1. Invoice Table:
2. Invoice_items Table(Join Table):