UnhandledPromiseRejectionWarning: TypeError: Assignment to constant variable

Question

I am doing my where clause outside the findAll() method to allow the user to send filter's or not in the request body. One of the values on my request body is categoryId that can be sent or not.

This is my code :

     const where = {}
        if (categoryId) {
            where = { '$subcategories.category_id$': categoryId
         }
        } 

    try {
            const establishments = await establishment.findAll({
                attributes: [
                    "id",
                    "description",
                    "latitude",
                    "longitude",
                    [sequelize.literal(' (6371 * acos ( '
                        + 'cos( radians(' + latitude + ') ) '
                        + '* cos( radians( latitude ) ) '
                        + '* cos( radians( longitude ) - radians(' + longitude + ') )'
                        + '+ sin( radians(' + latitude + ') )'
                        + '* sin( radians( latitude ))))'), 'distance']
                ],
                include: [{
                    attributes: [],
                    model: subcategory, as: 'subcategories',
                    required: false,
                },
                {
                    attributes: ["id", "name"],
                    model: certificate, as: 'certificates',
                    required: false,
                },
                ],

                where: {
                    where
                },

                establishments: ['id'],
            });
 } catch (error) {
        console.log(error)
        res.status(400).json({ Error: "Error while fetching the establishment" });
    }

Error given :

UnhandledPromiseRejectionWarning: TypeError: Assignment to constant variable.
 UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch()

The error is actually pretty clear. You declare `where` as a constant and then try to assign it a value. — Aioros, Apr 17 '20 at 19:41
Also I seem to have an invalid value on the $subcategories.category_id$, am I doing something wrong? @Aioros — José Nobre, Apr 17 '20 at 19:43
Does this answer your question? [Proper use of const for defining functions in JavaScript](https://stackoverflow.com/questions/33040703/proper-use-of-const-for-defining-functions-in-javascript) — Baruch, Apr 17 '20 at 19:43
I am having this error on $subcategories.category_id$ saying invalid value, am I doing something wrong? — José Nobre, Apr 17 '20 at 19:44

Akash Dathan · Accepted Answer · 2020-04-17T19:51:22.247

3

You cannot assign values to const variables once it is declared.

either use let

let where = {}

or

const where = {}
if (categoryId) {
  where['subcategories.category_id'] = categoryId
}

change where: { where } to where: where

edited Apr 17 '20 at 19:51

answered Apr 17 '20 at 19:44

Akash Dathan

4,348
2
24
45

it's also giving me an invalid value in $subcategories.category_id$, am I doing this wrong? – José Nobre Apr 17 '20 at 19:44
try removing the $ signs – Akash Dathan Apr 17 '20 at 19:45
try `where : { ...where }` – Akash Dathan Apr 17 '20 at 19:47
sorry did not understood, can you repeat? :) – José Nobre Apr 17 '20 at 19:48
or you can just do `where: where` – Akash Dathan Apr 17 '20 at 19:50
also, how can I put several wheres there? – José Nobre Apr 17 '20 at 19:51
what do you mean by several where ? – Akash Dathan Apr 17 '20 at 19:51
like if I wanted to search also by categoryName (also with null check) – José Nobre Apr 17 '20 at 19:53
ohh, just keep adding to the where object to the top. just use `where['key'] = value` instead of reassigning the whole thing. – Akash Dathan Apr 17 '20 at 19:54
can you show a quick example on the code you've writen? – José Nobre Apr 17 '20 at 19:55
same as the `const` example I have written, check for your condition in the `if` and keep adding to the where object. – Akash Dathan Apr 17 '20 at 19:56
@ AkashDathan can you give me a help in this question -> https://stackoverflow.com/questions/61282783/how-to-pass-object-as-a-data-type-to-a-data-model-in-sequilize – José Nobre Apr 18 '20 at 00:50
Let us [continue this discussion in chat](https://chat.stackoverflow.com/rooms/212032/discussion-between-jose-nobre-and-akash-dathan). – José Nobre Apr 19 '20 at 21:33

score 1 · Answer 2 · edited Nov 20 '21 at 08:36

1

const where = {}

If you create a variable with const, then you can't redeclare it again. You should use let instead.

let where = {}

edited Nov 20 '21 at 08:36

JW Geertsma

857
3
13
19

answered Nov 20 '21 at 06:52

Rajesh Senapati

201
1
8

UnhandledPromiseRejectionWarning: TypeError: Assignment to constant variable

2 Answers2