Develop Reference

How to transform array of strings into specific tree structure in Javascript

I get a list of file paths from the backend, it represents a folder structure and looks like this:
paths = ["path/to/file1.doc", "path/to/file2.doc", "foo/bar.doc]
The lengths of the paths are arbitrary. In order to use a file tree component (angular2-tree-component) I need to transform this data into the following format:
nodes = [
{
"name": "path",
"children": [
{
"name": "to",
"children": [
{"name": "file1.doc"},
{"name": "file2.doc"}
]
}
]
},
{
"name": "foo",
"children": [
{"name": "bar.doc"}
]
}
]
I think the most efficient way to transform the data is to
Map the array with the files mirroring a tree structure first and then to
Iterate over every key in order to finalise the "children/parent" relations.
Step one:
transformToTree(data) {
const tree = {};
function addPathsToTree(paths) {
let map = tree
paths.forEach(function(item) {
map[item] = map[item] || {};
map = map[item];
});
}
data.forEach(function(path) {
let pathPart = path.split('/');
addPathsToTree(pathPart);
});
return pathTree;
}
When passing "nodes" into the transformToTree function (transformToTree(nodes)), I get the following result:
{
"path": {
"to": {
"file1.doc": {},
"file2.doc": {}
}
},
"foo": {
"bar": {}
}
}
I don't know how to proceed from here = how to iterate over all the keys and values while building the final array in the required structure.
There are a few examples like this or that on SO, but I was not able to understand how I could adapt them to my needs.

I would go with two nested loops, one for pathes and one for the splitted names and find the name or create new objects.
var paths = ["path/to/file1.doc", "path/to/file2.doc", "foo/bar.doc"],
result = [];
paths.reduce((r, path) => {
path.split('/').reduce((o, name) => {
var temp = (o.children = o.children || []).find(q => q.name === name);
if (!temp) o.children.push(temp = { name });
return temp;
}, r);
return r;
}, { children: result });
console.log(result);
.as-console-wrapper { max-height: 100% !important; top: 0; }

How to add a new key:value pair to an already existing array state variable react native

I have a database function that returns some rows from a sqlite database then stores that in state
rows = await ReturnSelectedSymbolsDB()
this.setState({ symbols: rows })
The array looks something like this
symbols: [{key: "0", symbol:"name1", active: false},{key:"1", symbol:"name2",active: false}]
I have another database function which returns some rows and I wish to add them to symbol so it would look like this.
symbols: [{key: "0", symbol:"name1", active: false, newKey: newValue},{key:"1", symbol:"name2",active: false, newKey, newValue2}]
The second function will return multiple rows from the database which will be easy to match up with symbols as symbols:symbol will match otherFunction:symbol.
Normally you would just write this like a regular SQL query with a inner join joining the 2 tables together and then just putting the resulting rows in a state variable but I cannot in this case and must build the state variable piece by piece.
Can this be done is regular javascript?
EDIT:
Probably wasnt clear but newKey can have different values depending on what the name of the symbol is

You can create a new util function where you can add new key to all object inside the array.
addKey(symbol) {
let newArray=[...symbol];
return newArray.map((ele, i) => {
return {...ele, newKey: newValue};
})
}
Happy Coding :)

You have to insert your new value into your first function array, there are couples of way can insert object in array either use for loop or array manipulation functions.
var arrOfObj = [{
key: "0",
symbol:"name1",
active: false
}, {
key: "1",
symbol:"name1",
active: false
}, {
key: "2",
symbol:"name1",
active: false
}];
var result = arrOfObj.map(function(o) {
o.newKey = newValue;
return o;
})
console.log(result)
Note: I would prefer to go with inner join with two tables to return
combine array that not require any array manipulation.

You could do something like this if you know the key value corresponding to a given symbol:
for (let i = 0; i < symbols.length; i++){
symbols[i].newKey = "anyValue"
}

Try this,
let symbols = [
{ key: "0", symbol: "name1", active: false },
{ key: "1", symbol: "name2", active: false }
];
let newSymbols = [
{ key: "1", symbol: "name1", newKey: "fdds" },
{ key: "0", symbol: "name2", newKey: "sadav" }
];
mergeArray = (arrayOld, arrayNew) => {
let output = arrayOld.filter(item => {
let find = findMatchingItem(arrayNew, item.key);
item["newKey"] = find.newKey;
return item;
});
return output;
};
findMatchingItem = (array, matchingItemKey) => {
let output = null;
array.map(item => {
if (item.key == matchingItemKey) {
output = item;
}
});
return output;
};
let newArray = mergeArray(symbols, newSymbols);
console.log(newArray);
I have matched objects using "key" if you want from "symbol" just change "key" to "symbol"

how to get unique values from array of objects with addition of numbers

I'm working in wso2 carbon dashboard. My table is containing 2 fields (Name and Number). I Have duplicate name in the objects but with different number. I want unique name with addition of numbers.
[
{
"Name":"Abc",
"number":2
},
{
"Name":"bcd",
"number":3
},
{
"Name":"Abc",
"number":5
}
]
expected output
[
{
"name":"Abc",
"Number":7
},
{
"name":"bcd",
"Number":3
}
]
I'm using java script to achieve such task. please help me

Use Array#reduce method with a reference object.
var data = [{
"Name": "Abc",
"number": 2
}, {
"Name": "bcd",
"number": 3
}, {
"Name": "Abc",
"number": 5
}];
// object for index reference
var ref = {};
// iterate and generate the array
var res = data.reduce(function(arr, o) {
// check index already defined
if (!(o.Name in ref)) {
// if not defined then define index
ref[o.Name] = arr.length;
// and push the element
// you can also use
// arr.push({Name:o.Name, number:o.number});
arr.push(Object.assign({}, o));
} else {
// if index already defined update the number
arr[ref[o.Name]].number += o.number;
}
// return the array reference
return arr;
// set initial value as empty array
}, []);
console.log(res);

Filtering array of Objects Using Lodash or Javascript based on property name

I am Having the Array of objects. Like this
var result=[{"batchId":123, "licenseId":2345ef34, "name":"xxx"},
{"batchId":345, "licenseId":2345sdf334, "name":"www"},
{"batchId":145, "licenseId":234sdf5666, "name":"eee"},
{"batchId":455, "licenseId":asfd236645 },
{"batchId":678, "name":"aaa"}]
i want to have the array which is contains all the three properties. the Output should be like this.
[{"batchId":123, "licenseId":2345ef34, "name":"xxx"},
{"batchId":345, "licenseId":2345sdf334, "name":"www"},
{"batchId":145, "licenseId":234sdf5666, "name":"eee"}]
can anybody Help me on this

This is simple with the array .filter() method:
var result=[
{"batchId":123, "licenseId":"2345ef34", "name":"xxx"},
{"batchId":345, "licenseId":"2345sdf334", "name":"www"},
{"batchId":145, "licenseId":"234sdf5666", "name":"eee"},
{"batchId":455, "licenseId":"asfd236645" },
{"batchId":678, "name":"aaa"}
];
var filtered = result.filter(function(v) {
return "batchId" in v && "licenseId" in v && "name" in v;
});
console.log(filtered);
The function you pass to .filter() is called for each element in the array. Each element for which you return a truthy value will be included in the resulting array.
In the code above I simply test if all three of those specific properties are present, although there are other tests you could use that would get the same result for that data:
var result=[ {"batchId":123, "licenseId":"2345ef34", "name":"xxx"}, {"batchId":345, "licenseId":"2345sdf334", "name":"www"}, {"batchId":145, "licenseId":"234sdf5666", "name":"eee"}, {"batchId":455, "licenseId":"asfd236645" }, {"batchId":678, "name":"aaa"} ];
var filtered = result.filter(function(v) {
return Object.keys(v).length === 3;
});
console.log(filtered);
Note that you need to put your licenseId values in quotes, because they seem to be string values.

var result = [{
"batchId": 123,
"licenseId": '2345ef34',
"name": "xxx"
}, {
"batchId": 345,
"licenseId": '2345sdf334',
"name": "www"
}, {
"batchId": 145,
"licenseId": '234sdf5666',
"name": "eee"
}, {
"batchId": 455,
"licenseId": 'asfd236645'
}, {
"batchId": 678,
"name": "aaa"
}];
function hasProperties(object) {
return object.hasOwnProperty('batchId') && object.hasOwnProperty('licenseId') && object.hasOwnProperty('name')
}
result.filter(e => hasProperties(e));

JSON - array of objects into objects of arrays

I have a series of JSON entries:
[{"num": "1","name_A": "Alex" ,"name_B": "Bob"}, {"num": "2","name_A": "Anne" ,"name_B": "Barbra"}]
I am trying to convert this array of Objects as painlessly as possible into two objects - one with title name_A, and the second with the title name_B. Objects have to contain the title and an array of matching num-name pairs:
[{title: "name_A", names:[{"1", "Alex}, {"2", "Anne"}]}, {title:"name_B", names: [{"1", "Bob"}, {"2", "Barbra"}]}]
At first I tried simply to create two objects by reducing the array of object twice, once for name_A and second time for name_B and later glue everything together:
// get 'names' array
var name_A = objArray.reduce(function(memo, curr) {
memo.push({curr.num, curr.name_A})
return memo;
}, []);
But even this is failing. Why there is no push method for memo if I initialize reduce with an empty array?
And second question, am I on a right track or is there a better way to achieve this?

Comments inline, made a few minor corrections to the expectations.
var input = [{ "num": "1", "name_A": "Alex", "name_B": "Bob" }, { "num": "2", "name_A": "Anne", "name_B": "Barbra" }]
var output = input.reduce(function (a, b) {
// construct new objects and set their properties
var i = {};
i[b.num] = b.name_A;
var j = {};
j[b.num] = b.name_B;
// add them to our collection elements
a[0].names.push(i);
a[1].names.push(j);
return a;
// initializing our collection
}, [{ title: "name_A", names: [] }, { title: "name_B", names: [] }]);
// pretty print our output
console.log(JSON.stringify(output, null, " "))
var input = [{ "num": "1", "name_A": "Alex", "name_B": "Bob" }, { "num": "2", "name_A": "Anne", "name_B": "Barbra" }]
var output = input.reduce(function (a, b) {
// construct new objects and set their properties
var i = {};
i[b.num] = b.name_A;
var j = {};
j[b.num] = b.name_B;
// add them to our collection elements
a[0].names.push(i);
a[1].names.push(j);
return a;
// initializing our collection
}, [{ title: "name_A", names: [] }, { title: "name_B", names: [] }]);
so.log(output)
<pre id="output"></pre>
<script>
var so = {
log: function(o) {
document.getElementById("output").innerHTML = JSON.stringify(o, null, " ")
}
}
</script>

The problem with your code is that { curr.num, curr.name_A } is not a valid object, it's missing the property names. I've added properties num and name in my code below.
var name_A = [];
var name_B = [];
objArray.forEach(function(curr) {
name_A.push({num: curr.num, name: curr.name_a});
name_B.push({num: curr.num, name: curr.name_B});
});
var result = [
{ title: "name_A" }, names: name_A },
( title: "name_B" }, names: name_B }
];
Also, if you want to make an array out of the results of looping over an array, you should use .map rather than .reduce.

Assuming only property num is fixed. All other properties are treated as data, like name_A or name_B.
var a = [{ "num": "1", "name_A": "Alex", "name_B": "Bob" }, { "num": "2", "name_A": "Anne", "name_B": "Barbra" }],
result = [];
a.forEach(function (el) {
var num = el.num;
Object.keys(el).forEach(function (k) {
function tryFindIndexAndSetNames(aa, i) {
if (aa.title === k) {
result[i].names[num] = el[k];
return true;
}
}
if (k !== 'num' && !result.some(tryFindIndexAndSetNames)) {
var o = {};
o[num] = el[k];
result.push({ title: k, names: o });
}
});
});
document.write('<pre>' + JSON.stringify(result, 0, 4) + '</pre>');