Remove square bracket([ ]) in json file node JS - node.js

Question

I want to remove square bracket "[ ]" in json object or concatenate some array of object to one array of object.
This code for counting current stock
currentStock : ( req, res, next) => {
var listed_item = _(arr_items).map( (z) => {
var result = module.exports.getTransactionAfterDate(z.created_at, z.item_id);
return result;
})
var jsonContent = JSON.stringify(listed_item);
return res.send(jsonContent);
},
getTransactionAfterDate : (date, item_id) => {
var result = _(db_transaction).filter( (x) => {
return x.created_at > date && x.item_id == item_id;
});
return result;
}
this is "listed_item" json result
[
[{
"id": 30608,
"item_id": "A01001",
"quantity": 150,
"status": "OUT",
"created_at": "2020-02-10 16:11:51",
}],
[],
[{
"id": 30412,
"item_id": "A02001",
"quantity": 53,
"status": "OUT",
"created_at": "2020-02-06 14:44:20",
}, {
"id": 30482,
"item_id": "A02001",
"quantity": 33,
"created_at": "2020-02-07 15:26:50",
"updated_at": "2020-02-07 15:26:50",
}]
]
what i want is like this
[
{
"id": 30608,
"item_id": "A01001",
"quantity": 150,
"status": "OUT",
"created_at": "2020-02-10 16:11:51",
},
{
"id": 30412,
"item_id": "A02001",
"quantity": 53,
"status": "OUT",
"created_at": "2020-02-06 14:44:20",
}, {
"id": 30482,
"item_id": "A02001",
"quantity": 33,
"created_at": "2020-02-07 15:26:50",
"updated_at": "2020-02-07 15:26:50",
}
]
note
i tried concatenate "getTransactionAfterDate" inside "arr_items" map to join all array inside
var temp = [];
var listed_item = _(arr_items).map( (z) => {
temp = _(temp).concat(module.exports.getTransactionAfterDate(z.created_at, z.item_id));
var result = temp;
return result;
})
but the result is empty array
[ [], [], [] ]

Answer 1

Try this
currentStock : ( req, res, next) => {
var items = [];
_(arr_items).forEach( (z) => {
var result = module.exports.getTransactionAfterDate(z.created_at, z.item_id);
result.forEach( item => {
items.push(item);
}
})
var jsonContent = JSON.stringify(items);
return res.send(jsonContent);
},

Answer 2

You can 'flatten' the array with lodash, which will just merge all the arrays into a single one:
_(arr).flatten()
That should then give you a single array of your objects, with no empty arrays either.
.flatten() in the lodash docs here: https://lodash.com/docs/#flatten
So it would be something like this (edited based on comments):
currentStock : ( req, res, next) => {
var listed_item = _(arr_items).map( (z) => {
var result = module.exports.getTransactionAfterDate(z.created_at, z.item_id);
return result;
})
var flattened = _(listed_item).flatten();
var jsonContent = JSON.stringify(flattened);
return res.send(jsonContent);
},
Nice and simple! (if I correctly understood what you are trying to do :-)

Answer 3

this can be done with the combination of _.flatten (for this lodash is required) and Array.prototype.filter like shown below
let newArray = _.flatten(listed_item.filter(e => e.length > 0))