CODEWITHSUNDEEP
javascriptsequelize.js
Eggon
Eggon

Reputation: 2356

Sequelize (?): Save method stored in variable throws error when called: Unhandled rejection TypeError: Cannot read property 'isNewRecord' of undefined

I'm trying to store Sequelizes instance.save method in a variable to be called later. When I call it from that variable it throws error Unhandled rejection TypeError: Cannot read property 'isNewRecord' of undefined.

Save is performed on an associated object in array loaded thorough eager loading. If I call directly the code I'm trying to store, it works. It fails just when stored.

My code:

models.Person.hasMany(models.TaskExecutor, { foreignKey: 'personID' });
models.TaskExecutor.belongsTo(models.Person, { foreignKey: 'personID' });

const options = {
    include: [
        {
            model: models.TaskExecutor,
            where: { ... }
        }
    ]
};

let handler;

models.Person.findOne(options)
    .then(person => {
        handler = person.task_executors[0].save;
        handler().then(...); // THIS THROWS ERROR

        // HOWEVER
        person.task_executors[0].save().then(...); // WORKS JUST FINE
    })

Any idea what might be the cause for this?

Upvotes: 0

Views: 81

Answers (1)

Adrian
Adrian

Reputation: 46

You probably need to bind the this keyword variable when creating the handler because the save method is a class method. You can do it like this:

const handler = person.task_executors[0].save.bind(person.task_executors[0]);
handler.then() ....

You can read more about this here https://medium.com/quick-code/understanding-the-this-keyword-in-javascript-cb76d4c7c5e8

Upvotes: 1

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