Flatten result from .findAll

Issue Description

Is your feature request related to a problem? Please describe.

I usually need to get the value list of a certain column instead of the whole row data. To do so, currently, I call .findAll to get a list of objects then .map to have the final result. Basically need to do 2 steps and create an intermediate variable. This happens quite frequently in my code.

Django has an option to flatten the result https://docs.djangoproject.com/en/2.2/ref/models/querysets/#values-list

Describe the solution you’d like

Add .flat() or .flatten() function

const restaurantIds = await Restaurant.findAll({
    where: {
        status: "active"
    },
    attributes: ["id"]
}).flat();

Why should this be in Sequelize

If someone passes 1 column name to attributes, most likely the next step will be transforming the result to a list of single-column values.

And, the above code is elegant and more convenient compared with the following:

const restaurants = await Restaurant.findAll({
    where: {
        status: "active"
    },
    attributes: ["id"]
});
const restaurantIds = restaurants.map((r) => r.id);

// OR:
const restaurantIds = (await Restaurant.findAll({
    where: {
        status: "active"
    },
    attributes: ["id"]
})).map((r) => r.id);

// OR:
const restaurantIds = await Restaurant.findAll({
    where: {
        status: "active"
    },
    attributes: ["id"]
}).then((result) => result.map((r) => r.id));

Describe alternatives/workarounds you’ve considered

Yes, the solutions I show above. It’s ok but not super convenient.

Additional context

I can work on this

Issue Template Checklist

Is this issue dialect-specific?

• No. This issue is relevant to Sequelize as a whole.
• Yes. This issue only applies to the following dialect(s): XXX, YYY, ZZZ

Would you be willing to resolve this issue by submitting a Pull Request?

• Yes, I have the time and I know how to start.
• Yes, I have the time but I don’t know how to start, I would need guidance.
• No, I don’t have the time, although I believe I could do it if I had the time…
• No, I don’t have the time and I wouldn’t even know how to start.

[papb]

Hello! I think this is unnecessary complexity to be added in the core library. Calling .map(r => r.id) seems easy enough to me. In fact, if we had this .flat() or even a { flat: true } option, readers would have to check our docs to really discover what it is. If you are worried about performance, consider using { raw: true } in your query. What do you think?

[github-actions[bot]]

This issue has been automatically marked as stale because it has been open for 7 days without activity. It will be closed if no further activity occurs. If this is still an issue, just leave a comment or remove the “stale” label. 🙂