I am using Nodejs & would like to group my object array based on few attributes.
example attr_id & type will be unique
const normalizedList =[ {
"attr_id": 1,
"type": "color",
"value_index": 10,
"value_label": "Blue"
},
{
"attr_id": 1,
"type": "color",
"value_index": 15,
"value_label": "Red"
},
{
"attr_id": 2,
"type": "size",
"value_index": 10,
"value_label": "Small"
},
{
"attr_id": 2,
"type": "size",
"value_index": 14,
"value_label": "Big"
}
];
Needs to be converted to
[{
"attr_id": 1,
"type": "color",
"values": [{
"index": 10,
"label": "Blue"
}, {
"index": 15,
"label": "Red"
}
]
}, {
"attr_id": 2,
"type": "size",
"values": [{
"index": 10,
"label": "Small"
}, {
"index": 14,
"label": "Big"
}
]
}
]
I was trying to do this without any packages like "underscore" or "json-aggregate". as not many places in the code we do any grouping/aggregation
Below is how I was able to solve
const groupJson = (arr,g_label) =>{
// group the list by 'attr_id'
const groupedAttrList = normalizedList.reduce((acc, obj)=>{
let key = obj[g_label]
if (!acc[key]) {
acc[key] = []
}
acc[key].push(obj)
return acc
},{});
const finalArray = [];
// Now iterate over the groupedAttrList
for (let typeRow in groupedAttrList){
let resultObj = {};
let tempRow = groupedAttrList[typeRow];
// as attr_id,type are unique for the set; picking it from 1st
const {attr_id,type} = tempRow [0];
resultObj .attr_id= attr_id;
resultObj .type= type;
// get all the values
resultObj .values = tempRow .map(v=>{
return {index:v.value_index,label:v.value_label};
});
finalArray.push(resultObj );
}
console.log(finalArray);
};
Test
let tempResult = groupJson(normalizedList,'attr_id');
wanted to learn if there are better ways to do it
Well I guess you can make it more dynamic(something to group by an unknown amount of attributes)
First, I give you the answer in your output format in structure[{values:[...objectsInGroup],...groupingInfo}, ...otherGroupObjects]
const myList=[{"attr_id":1,"type":"color","value_index":10,"value_label":"Blue"},{"attr_id":1,"type":"color","value_index":15,"value_label":"Red"},{"attr_id":2,"type":"size","value_index":10,"value_label":"Small"},{"attr_id":2,"type":"size","value_index":14,"value_label":"Big"}]
function groupList(list,attributes){
var cache={} //for finding elements that have the same attributes
for(let item of list){
let ID=attributes.map(attr=>item[attr]).join('-')
//items with same ID would be grouped together
cache[ID]? cache[ID].values.push(item): cache[ID]={values:[item]}
//if ID exists.. add to the group, else make the group
attributes.forEach(key=>{
if(!cache[ID][key]){ cache[ID][key]=item[key] }
})
}
return Object.values(cache)
}
const newList=groupList(myList,['attr_id','type'])
console.log(newList)But what if there was a values attribute that is in the original items in the list that you wanted it sorted by? only one value can exist per key.. in that case you can change the structure to[{values:[...objectsInGroup],info:{...groupingInfo}} ...otherGroupObjects]
const myList=[{"attr_id":1,"type":"color","value_index":10,"value_label":"Blue"},{"attr_id":1,"type":"color","value_index":15,"value_label":"Red"},{"attr_id":2,"type":"size","value_index":10,"value_label":"Small"},{"attr_id":2,"type":"size","value_index":14,"value_label":"Big"}]
function groupList(list,attributes){
var cache={} //for finding elements that have the same attributes
for(let item of list){
let ID=attributes.map(attr=>item[attr]).join('-')
//items with same ID would be grouped together
cache[ID]? cache[ID].values.push(item): cache[ID]={values:[item]}
//if ID exists.. add to the group, else make the group
if(!cache[ID].info){
cache[ID].info={} //info about the grouping of this array
attributes.forEach(key=>cache[ID].info[key]=item[key])
}
}
return Object.values(cache)
}
const newList=groupList(myList,['attr_id','type'])
console.log(newList)Im not necessarily sure if this is any better, but this is how I would maybe go about this. You could easily wrap this into a function
const finalObjects = [];
const checkIdInArray = (id) => finalObjects.find((obj) => obj.attr_id === id);
normalizedList.forEach((element) => {
if (!checkIdInArray(element.attr_id)) {
// Then add to array as its not been added yet
finalObjects.push({
attr_id: element.attr_id,
type: element.type,
values: [
{
index: element.value_index,
label: element.value_label,
},
],
});
return;
}
// Get the index of the existing id
const arrIndex = finalObjects.findIndex((e) => e.attr_id === element.attr_id);
finalObjects[arrIndex].values.push({
index: element.value_index,
label: element.value_label,
});
});
console.log(JSON.stringify(finalObjects));