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Ticket: create a new model, and associate to another modal

Create Model

For example, this ticket detail is creating a new model, contains information about some specific url.

From Sequelize official documentation, Models are defined with sequelize.define('name', {attributes}, {options}).

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const LinkDetail = sequelize.define('link_detail', {
    url: {
        type: Sequelize.STRING
    },
    description: {
        type: Sequelize.STRING
    }
})

and for future repeat use, wrap it with module.exports: 

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module.exports = (sequelize, DataTypes) => {
    const LinkDetail = sequelize.define('link_detail', {
        url: {
            type: Sequelize.STRING
        },
        description: {
            type: Sequelize.STRING
        }
    });
    return LinkDetail;
}

Associations

So far, at this point, half of ticket is done, get into Associations, in this ticket, this link model is associated to another model which is called story model, and they are One-To-One associations.

One-To-One associations are associations between exactly two models connected by a single foreign key.

BelongsTo

BelongsTo associations are associations where the foreign key for the one-to-one relation exists on the source model.

HasOne

HasOne associations are associations where the foreign key for the one-to-one relation exists on the target model.

Difference between HasOne and BelongsTo

Read the official documentation, they have a greate example! click here

After comparing the differences between belongsTo and hasOne, in this case we should use hasOne:

LinkDetail.hasOne(Story), add storyId attribute to target model which is Story model.

Add association to model define function

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module.exports = (sequelize, DataTypes) => {
    const LinkDetail = sequelize.define('link_detail', {
        url: {
            type: Sequelize.STRING
        },
        description: {
            type: Sequelize.STRING
        }
    });
    LinkDetail.associations = () => {
        LinkDetail.hasOne(Story);
    };
    return LinkDetail;
}

In the end

Of cause, in my real ticket, its not this easy, there are more detail about model structure, more attributes and more associations between others. Need to spend time to read through the documentation, it is always my best friend, when I start something new.

Once again, read the documentation! IT’S FREE!!!