Cannot read property 'map' of undefined in sequelize nodejs - arrays

Question

This is my api:
exports.getService = function(req, res) {
var limit = 10; // number of records per page
var offset = 0;
Service.findAndCountAll({
raw: true,
where: {
shop: req.user.shop
}
}).then((data) => {
var page = req.params.page; // page number
var pages = Math.ceil(data.count / limit);
offset = limit * (page - 1);
Service.findAll({
// raw: true,
limit: limit,
offset: offset,
$sort: {
id: 1
},
where: {
shop: req.user.shop
},
include: [{
model: Categoryservice,
attributes: ['id'],
include: [{
model: Category,
attributes: ['id', 'name'],
}]
}],
}).then(function (services) {
var services=JSON.parse(JSON. stringify(services));
console.log('=====stringify==========>>',services);
var arr = services.categoryservices.map(item => item.category.id)
services.cats = arr;
delete services.categoryservices;
console.log('only for the testing========>',services);
res.status(200).json({
'result': services,
'count': data.count,
'pages': pages
});
});
}).catch(function(error) {
res.status(500).send('Internal Server Error');
});
};
I am using map in last then fuction ,
It contains a error map undefined in the server..
I want want a out like below given json using the map fuction.
Actually i need this out put:
{
"id": 2,
"service": "mobile",
"min": "20",
"per": "10",
"tax": "1",
"cats": [
1,
2
]
}
my JSON. stringify(services) out put is:
=====stringify==========>> [ { id: 2,
username: null,
name: null,
image: null,
service: 'mobile',
shop: '$2a$10$NWpbmgtzQAxRZ1ugvdC7LOlorBU36xoGHm1L.k.KmFqDO/7oSmBLu',
min: '20',
per: '10',
tax: '1',
activity: null,
createdAt: '2018-03-14T07:30:57.000Z',
updatedAt: '2018-03-14T07:30:57.000Z',
categoryservices: [ [Object], [Object] ] },
{ id: 1,
username: 'sam',
name: 'New Service',
image: '/images/uploads/22-Feb-2018/f96334384cd78754454c5e4e05e20fc0-dragon_pattern_red_black_9666_1920x1080.jpg',
service: 'battery',
shop: '$2a$10$NWpbmgtzQAxRZ1ugvdC7LOlorBU36xoGHm1L.k.KmFqDO/7oSmBLu',
min: '5',
per: '1',
tax: '1',
activity: '2018-03-14T06:01:36.000Z',
createdAt: '2018-03-14T06:01:36.000Z',
updatedAt: '2018-03-14T06:01:36.000Z',
categoryservices: [] } ]
I was beginner of using map function,
so,I am confused in map ,
so please give any solution to this problem.

Answer 1

You are stringifying your array that comes back. You can't do that if you plan to use .map on it. Remove that code and try again.
.then(function (services) {
var arr = services.categoryservices.map(item => item.category.id)
services.cats = arr;
delete services.categoryservices;
console.log('only for the testing========>',services);
res.status(200).json({
'result': services,
'count': data.count,
'pages': pages
});
});
I think we are missing something because the output you pasted doesn't have the category.id attribute that you are returning from the item passed in to map. Is that what you are trying to target? That's off topic, but this code may not work for what you are trying to achieve but will run the map though.

Answer 2

Looks like services is an array, based on the console.log. If you want the id's of all categories, you can do
let categoryIds = [];
categoryIds = services.reduce((categoryIds, service) => {
let ids = service.categoryservices.map(category => category.id);
for(let id of ids) {
if(categoryIds.indexOf(id) === -1) {
categoryIds.push(id)
}
}
return categoryIds;
}, categoryIds);
If you want to have category ids as cats in each service, you can do,
var services=JSON.parse(JSON. stringify(services));
services.forEach(service) => {
service.cats = service.categoryservices.map(category => category.id);
delete service.categoryservices;
});
res.status(200).json({
'result': services,
'count': data.count,
'pages': pages
});
Hope this helps!