AngularJS combining objects in an array by properties
I have a large array of objects (1500+) and the objects correspond to one of the properties. Thus, the total number of objects can be reduced, for example. to improve performance in ng-repeat. I'm a bit new to AngularJS and JS so help is greatly appreciated!
my array of objects (simplified)
myArray = [
{
"role": "user111",
"operation": "create",
"concept": "folder"
},
{
"role": "user111",
"operation": "create",
"concept": "task"
},
{
"role": "user111",
"operation": "delete",
"concept": "task"
},
{
"role": "user222",
"operation": "create",
"concept": "folder"
},
{
"role": "user222",
"operation": "create",
"concept": "task"
},
{
"role": "user222",
"operation": "delete",
"concept": "task"
}
]
desired result
dreamArray = [
{
"role": "user111",
"operation": {
"create": ["folder", "task"],
"delete": ["task"]
}
},
{
"role": "user222",
"operation": {
"create": ["folder", "task"],
"delete": ["task"]
}
}
]
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You can do this using forEach()
loop and thisArg
.
var myArray = [{"role":"user111","operation":"create","concept":"folder"},{"role":"user111","operation":"create","concept":"task"},{"role":"user111","operation":"delete","concept":"task"},{"role":"user222","operation":"create","concept":"folder"},{"role":"user222","operation":"create","concept":"task"},{"role":"user222","operation":"delete","concept":"task"}]
var result = [];
myArray.forEach(function(e) {
if(!this[e.role]) {
this[e.role] = {role: e.role, operation: {[e.operation]: [e.concept]}}
result.push(this[e.role]);
} else {
var op = this[e.role].operation[e.operation]
if(op) op.push(e.concept)
else this[e.role].operation[e.operation] = [e.concept]
}
}, Object.create(null))
console.log(result)
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You can use a hash table and keep the link to the groups.
var array = [{ role: "user111", operation: "create", concept: "folder" }, { role: "user111", operation: "create", concept: "task" }, { role: "user111", operation: "delete", concept: "task" }, { role: "user222", operation: "create", concept: "folder" }, { role: "user222", operation: "create", concept: "task" }, { role: "user222", operation: "delete", concept: "task" }],
grouped = array.reduce(function (hash) {
return function (r, o) {
if (!hash[o.role]) {
hash[o.role] = {};
r.push({ role: o.role, operation: hash[o.role]});
}
hash[o.role][o.operation] = hash[o.role][o.operation] || [];
hash[o.role][o.operation].push(o.concept);
return r;
};
}(Object.create(null)), []);
console.log(grouped);
.as-console-wrapper { max-height: 100% !important; top: 0; }
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Using reduce()
andfind()
var myArray = [{ role: "user111", operation: "create", concept: "folder" }, { role: "user111", operation: "create", concept: "task" }, { role: "user111", operation: "delete", concept: "task" }, { role: "user222", operation: "create", concept: "folder" }, { role: "user222", operation: "create", concept: "task" }, { role: "user222", operation: "delete", concept: "task" }],
const dreamArray = myArray.reduce((acc, item) => {
let obj = acc.find(e => e.role === item.role);
if(!obj){
obj = {"role" : item.role, "operation": {[item.operation]: [item.concept]}};
acc.push(obj);
}else{
obj.operation[item.operation] = obj.operation[item.operation] || [];
obj.operation[item.operation].push(item.concept);
}
return acc;
}, []);
console.log(dreamArray);
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As I mentioned in my comment, if you manage to get the data already sorted by property role
(which is what you say), then the required operation comes down to a very simple operation .reduce()
and can be implemented with O (n) time complexity as follows;
var data = [{"role":"user111","operation":"create","concept":"folder"},{"role":"user111","operation":"create","concept":"task"},{"role":"user111","operation":"delete","concept":"task"},{"role":"user222","operation":"create","concept":"folder"},{"role":"user222","operation":"create","concept":"task"},{"role":"user222","operation":"delete","concept":"task"}],
result = data.reduce((r,c,i) => !i || r[r.length-1].role !== c.role ? r.concat({"role": c.role, "operation": c.operation === "create" ? {"create": [c.concept], "delete": []}
: {"create": [], "delete": [c.concept]}})
: r[r.length-1].operation[c.operation].includes(e => e === c.concept) ? r
:(r[r.length-1].operation[c.operation].push(c.concept),r), []);
console.log(result);
.as-console-wrapper { max-height: 100% !important; top: 0; }
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