How to get Nested data in node js - node.js

Question

I want to get items per category in node js. how to get it. Here is the example that i want
"status": true,
"total_results": 4,
"categories": [
{
"id": 2,
"name": "Category 1",
"items":[
{
"name" :"item1"
},
{
"name": "item2"
}
]
},
{
"id": 4,
"name": "Category 2",
"items":[
{
"name" :"item1"
},
{
"name": "item2"
}
]
}
]
}

Answer 1

Here is the code i write for getting above array result in nodejs
pool.query(`Select * FROM categories WHERE catalog_id = '${fields.catalog_id}'`, async (error, result, field) => {
if (error) { // if error
console.log(error);
return false;
}
var Catarr = result.map((item,index)=>item.id)
pool.query(`Select * FROM items WHERE category_id IN (${Catarr})`, async (error, menuItems, field) => {
if (error) { // if error
console.log(error);
return false;
}
var parsed_items = [];
await result.forEach((item,index)=>{
var items = menuItems.filter((p_item)=>p_item.category_id == item.id)
var obj = {
name: item.name,
id: item.id,
items
}
parsed_items.push(obj)
})
res.status(200).json({status:true,total_results:result.length,categories:parsed_items});
});
});

Answer 2

Sharing my suggestion as per my understanding; Please refer to below code snippet:
const data={ "status": true,
"total_results": 4,
"categories": [
{
"id": 2,
"name": "Category 1",
"items":[
{
"name" :"item1"
},
{
"name": "item2"
}
]
},
{
"id": 4,
"name": "Category 2",
"items":[
{
"name" :"item1"
},
{
"name": "item2"
}
]
}
]
};
const expectedResult=data.categories.reduce((iter, item)=>{
iter[item.name]=item.items? item.items.length : 0; // we can use item.id if required
return iter;
}, {});
alert(JSON.stringify(expectedResult));
console.log('Items per category - ',expectedResult);