Create new JSON string from array - javascript

Fairly new to JSON and I'm trying to get my head around conversions. I have an array:
['Role1', 'Role2', 'Role3']
and I'm trying to stringify it so that it reads as
{"Role1": true, "Role2": true, "Role3": true}
So far I've tried assigning the original array to an object and the calling stringify but I can't figure out how to add the boolean value in the string. Thanks in advance.

You'll have to create an intermediate reduce function to assign those values before converting to JSON.
const data = ['Role1', 'Role2', 'Role3']
const makeJson = () =>
JSON.stringify(data.reduce((a, c) => ({ ...a, [c]: true }), {}))
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/Reduce

Is this what you need as output?
const arr = ['Role1', 'Role2', 'Role3']
const result = JSON.stringify(arr.reduce((a, n)=>{
return {
...a,
[n]: new Boolean(true).toString()
}
},{}))
console.log(result)

Another approach could be to combine Object.fromEntries with Array.prototype.map
const data = ['Role1', 'Role2', 'Role3']
const result = Object.fromEntries(data.map(s => [s, true]));
console.log(JSON.stringify(result));

This should do the trick:
let rolesArray = ['Role1', 'Role2', 'Role3'];
let rolesObject = {};
// iterate over roles to fill an object
rolesArray.forEach((role) => {
rolesObject[role] = true;
});
JSON.stringify(rolesObject) // Outputs the desired string
Or in a more concise way but less readable for a SO example :
JSON.stringify(rolesArray.reduce((o, s) => { o[s] = true; return o }, {}));

I have a preference for using the for-loop — still valid but other methods will be much short.
var array = ["Role1", "Role2", "Role3"],
json = {};
for (i = 0; i < array.length; i++) {
json[array[i]] = true;
}
console.log(json);

Use reduce() so we can set the value to true without a second loop
Using the spread operator (...) to merge the objects
const data = ['Role1', 'Role2', 'Role3'];
const obj = data.reduce((prev, cur) => ({ ...prev, [cur]: true }), {});
console.log(obj);
console.log(JSON.stringify(obj));
{
"Role1": true,
"Role2": true,
"Role3": true
}
{"Role1":true,"Role2":true,"Role3":true}

if you want to do that you must use code Below .
json-encode(Array)

Related

How do construct ForEach into map in javascript

I have sample JSON in form of
var sample=[{"id":200,"children":[{"value":300,"type":"SINGLE"},{"value":400,"type":"CLASSIC"},{"value":600,"type":"DUAL"}]},{"id":300,"children":[{"value":500,"type":"TRIO"},{"value":600,"type":"MUSICAL"},{"value":700,"type":"UMBRELA"}]}]
var result = [];
sample.forEach(function(e){
let obj = {}
obj.id=e.id
obj['somekey']=e.children[0].value
obj['someanotherkey']=e.children[1].type
result.push(obj);
})
console.log(result)
How do i can achieve same using map es-6
var sample=[{"id":200,"children":[{"value":300,"type":"SINGLE"},{"value":400,"type":"CLASSIC"},{"value":600,"type":"DUAL"}]},{"id":300,"children":[{"value":500,"type":"TRIO"},{"value":600,"type":"MUSICAL"},{"value":700,"type":"UMBRELA"}]}]
var output = sample.map(({ id, children }) => ({ id, ...children[0] }));
console.log(output);
.map() returns an array, so you must set up a variable to hold that result. Then, within the loop, you use return to effectively push items into the array.
var sample=[{"id":200,"children":[{"value":300,"type":"SINGLE"},{"value":400,"type":"CLASSIC"},{"value":600,"type":"DUAL"}]},{"id":300,"children":[{"value":500,"type":"TRIO"},{"value":600,"type":"MUSICAL"},{"value":700,"type":"UMBRELA"}]}];
let result = sample.map(function(e){
let obj = {}
obj.id=e.id;
obj['value']=e.children[0].value;
obj['type']=e.children[0].type
return obj;
});
console.log(result);
If you want to be able to chose the children index:
const getDataChild = (a, i) => a.map(({id, children:ch}) => ({id, ...ch[i]}));
console.log(getDataChild(sample, 0)); // where 0 is the desired index

I have two arrays and want to concat and send the data via post method

I have two arrays one is of keys and one is of its values
a=[name,place,job],
b=[John,Atlanta,Engineer]
I want to concat a and b and send it by post method like
xyz={
'name':'John',
'place:'Atlanta',
'job':'Engineer'
}
Working Demo
let a = ['name','place','job'];
let b = ['John','Atlanta','Engineer'];
let payload = a.reduce((obj, item, index) => (obj[item] = b[index], obj) ,{});
console.log(payload);
Service
this.http.post<any>(this.URL, payload);
You can iterate over an source array and then create a object with key and value then use Object.assign.
For ex:
a = ["name", "place", "job"];
b = ["John", "Atlanta", "Engineer"];
xyz = {};
constructor() {
this.a.forEach((item, index) => {
var obj = {
[this.a[index]]: this.b[index] || ""
};
Object.assign(this.xyz, obj);
});
console.log(this.xyz);
}
Working Demo
it is possible to use Object.assign and map methods:
let a = ['name','place','job'];
let b = ['John','Atlanta','Engineer'];
const result = Object.assign(...a.map((k, i) => ({[k]: b[i]})))
console.log(result);

Convert JSON to Array of Objects using lodash

I have a JSON object in NoSql database in this format. We are getting this data after migrating some records from some other database and these are multi-valued fields.(Basically we are trying to clean the data for further processing).
{
"BPContName":"aName;bName;cName",
"BPContEmail":"aEmail;bEmail;cEmail",
"BPContPWID":"aPWID;bPWID;cPWID"
}
I want to add another key "bpTableDataName" in the same JSON which should have this format and values,
"bpTableDataName": [
{
"name": "aName",
"email": "aEmail",
"pwdid": "aPWID"
},
{
"name": "bName",
"email": "bEmail",
"pwdid": "bPWID"
},
{
"name": "cName",
"email": "cEmail",
"pwdid": "cPWID"
}
],
Is there a way we can achieve this using lodash?
Try following code -
o = {
"BPContName": "aName;bName;cName",
"BPContEmail": "aEmail;bEmail;cEmail",
"BPContPWID": "aPWID;bPWID;cPWID"
}
map = { "BPContName" : "name", "BPContEmail": "email", "BPContPWID": "pwdid" }
const result = _.reduce(o, (arr, v, k) => ( v.split(";").forEach((x,i) => _.set(arr, `${i}.${map[k]}`, x)), arr ), [])
console.log(result)
<script src="https://cdn.jsdelivr.net/npm/lodash#4.17.11/lodash.min.js"></script>
You can use split() to split the values into an array.
Then iterate over the array and create the require json and then push that into results.
Check this out.
var data = {
"BPContName":"aName;bName;cName",
"BPContEmail":"aEmail;bEmail;cEmail",
"BPContPWID":"aPWID;bPWID;cPWID"
}
var names = data.BPContName.split(';');
var emails = data.BPContEmail.split(';');
var pwids = data.BPContPWID.split(';');
var results = [];
for(var i = 0 ; i < names.length; i++) {
var obj = {
name: names[i],
email: emails[i],
pwdid: pwids[i]
}
results.push(obj);
}
console.log(results)
You could reduce the entries returned by Object.entries like this:
let obj = {
"BPContName": "aName;bName;cName",
"BPContEmail": "aEmail;bEmail;cEmail",
"BPContPWID": "aPWID;bPWID;cPWID"
}
let bpTableDataName = Object.entries(obj).reduce((r, [key, value]) => {
let splits = value.split(";");
key = key.replace("BPCont", "").toLowerCase();
splits.forEach((split, i) => (r[i] = r[i] || {})[key] = split)
return r;
}, [])
obj.bpTableDataName = bpTableDataName;
console.log(obj)
Object.entries returns an array of key-value pair. Loop through each of them
split the each value at ;
get the key by removing BPCont part and making it lowerCase
Loop through the splits and update specific keys of objects at each index
Update:
Since you have an extra d in the output's key, you can create a mapping object:
propertyMap = {
"BPContName": "name",
"BPContEmail": "email",
"BPContPWID": "pwdid"
}
And inside the reduce, change the replace code to this:
key = propertyMap[key]
Using Object.assign, Object.entries, Array#map and the spread operator make this trivial
const inputdata = {
"BPContName":"aName;bName;cName",
"BPContEmail":"aEmail;bEmail;cEmail",
"BPContPWID":"aPWID;bPWID;cPWID"
};
const t1=Object.assign({},...Object.entries(inputdata).map(([k,v])=>({[k]:v.split(';')})));
inputdata.bpTableDataName=t1.BPContName.map((name,i)=>({name,email:t1.BPContEmail[i],pwdid:t1.BPContPWID[i]}));
console.log(inputdata);
Of course, it wouldn't be me without a one-liner
const obj = {
"BPContName":"aName;bName;cName",
"BPContEmail":"aEmail;bEmail;cEmail",
"BPContPWID":"aPWID;bPWID;cPWID"
};
// one line to rule them all
obj.bpTableDataName=Object.entries(obj).reduce((r,[k,v])=>(v.split(';').forEach((v,i)=>(r[i]=r[i]||{})[{BPContName:'name',BPContEmail:'email',BPContPWID:'pwdid'}[k]]=v),r),[]);
//
console.log(obj);
Basically what you need is to zip it.
Snippet:
let obj = {"BPContName":"aName;bName;cName","BPContEmail":"aEmail;bEmail;cEmail","BPContPWID":"aPWID;bPWID;cPWID"},
res = _.zipWith(
..._.map(obj, v => v.split(';')),
(name, email, pwid) => ({name, email, pwid})
);
console.log(res)
<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.11/lodash.min.js"></script>
Note, the sequence of the parameters we have to put such a way, the original object give us values when using Object.values or giving us keys when using Object.keys usually it is alphabetical order. But, In case in any env the order is not guranted we can sort it with a sequence of keys as a metadata.
Or else you can explicitly pass the arguments like:
(obj.BPContName.split(';'), obj.BPContEmail.split(';'), obj.BPContPWID.split(';'))
You can use lodash's _.flow() to create a function. Use _.map() with _.overArgs() to create a function that splits the values, format the key, and then converts them to an array of pairs using _.unzip(), for example [['name', 'x'], ['name', 'y']]. Transpose the array of arrays with _.unzip() to combine pairs of different properties. Then use _.map() to iterate, and convert each array of pairs to an object using _.fromPairs().
const { flow, partialRight: pr, map, unzip, overArgs, times, size, constant, split, fromPairs } = _
const keysMap = new Map([['BPContName', 'name'], ['BPContEmail', 'email'], ['BPContPWID', 'pwdid']])
const formatKey = key => keysMap.get(key)
const splitVals = pr(split, ';')
const fn = flow(
pr(map, overArgs(
(vals, k) => unzip([vals, times(size(vals), constant(k))]),
[splitVals, formatKey])
),
unzip, // transpose
pr(map, fromPairs) // convert each pairs array to object
)
const data = {
"BPContName":"aName;bName;cName",
"BPContEmail":"aEmail;bEmail;cEmail",
"BPContPWID":"aPWID;bPWID;cPWID"
}
const results = fn(data)
console.log(results)
<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.11/lodash.js"></script>

Transform from string array to hashmap in Lodash

What is the most precise way to transform from this
["access","edit","delete"]
to this
{access:true, edit:true, update:true}
Currently i loop to assign each value in object but i wonder if lodash already provide function for this
Use reduce(). This can all be done with a simple one-liner, that doesn't require any libraries:
const input = ["access","edit","delete"];
console.log(
input.reduce((obj, key) => { obj[key] = true; return obj; }, {})
);
With the new es6 spread syntax, you can even make this easier:
const input = ["access","edit","delete"];
console.log(
input.reduce((obj, key) => ({...obj, [key]: true}), {})
);
LODASH
You can map it to a array of entries and then simply use fromPairs of lodash
_.fromPairs(input.map(k=>[k, true]))
var input = ["access","edit","delete"];
var res = _.fromPairs(input.map(k=>[k,true]));
console.log(res);
<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.11/lodash.min.js"></script>
ES6
You can map your input to a key (your each input) value (true) pair of objects and assign them.
Object.assign( ...input.map(k=>({[k]: true})))
var input = ["access","edit","delete"]
var res = Object.assign( ...input.map(k=>({[k]: true})));
console.log(res);
In case you want a Map object you can map your input to entries (as used in lodash example) and simply construct a new Map like
new Map(input.map(k=>[k, true]))
No need to import a library for something so simple, just reduce the array of keys into an object indexed by those keys:
const input = ["access","edit","delete"];
const output = input.reduce((a, key) => Object.assign(a, {[key]: true}), {});
console.log(output);
Or, assigning to the property of the accumulator rather than using Object.assign:
const input = ["access","edit","delete"];
const output = input.reduce((a, key) => {
a[key] = true;
return a;
}, {});
console.log(output);
If you absolutely want to use lodash (As opposed to the above vanilla javascript reduce() answers), you can use _.mapValues() to accomplish this:
const input = ["access","edit","delete"];
const output = _.mapValues(_.keyBy(input), () => true)
console.log(output);
<script src="https://cdn.jsdelivr.net/npm/lodash#4.17.11/lodash.min.js" integrity="sha256-7/yoZS3548fXSRXqc/xYzjsmuW3sFKzuvOCHd06Pmps=" crossorigin="anonymous"></script>

Converting a String to Multiple objects (javascript)

I have the following string: Jack:13,Phil:15,Lucy:12I'm trying to fetch objects from this string.
This string would have 3 people objects with their ages. How can this be achieved?
I've tried the following:
var s = 'Jack:13,Phil:15,Lucy:12'
var obj1 = eval("("+s+")");
var obj2 = JSON.parse(s);
Logging any of the obj variables returns errors. Am I missing a simple trick here? Any explanation would be appreciated, thanks.
In general, if you're doing replaces on a string to turn it into something you can pass eval or JSON.parse, that's probably not your best approach. An in particular, avoid using eval (or its cousin new Function) when you can (you certainly can here), and always avoid eval (or its cousin new Function) with untrusted input.
A pair of splits with map does it:
const s = 'Jack:13,Phil:15,Lucy:12'
const people = s.split(",")
.map(e => e.split(":"))
.map(([name, age]) => ({name, age}));
console.log(people);
...or in ES5:
var s = 'Jack:13,Phil:15,Lucy:12'
var people = s.split(",")
.map(function(e) { return e.split(":"); })
.map(function(e) { return {name: e[0], age: e[1]}; });
console.log(people);
I'm not sure why I did two maps rather than just doing the second split and creating the object in the same callback; I guess I'm thinking more and more in a "functional programming" way. I'd change it, but Eddie's answer already does it in a single map, so...
...(edit) but since it looks like you wanted separate properties rather than using the person's name like Eddie did, here's an example of the above but with just a single map:
const s = 'Jack:13,Phil:15,Lucy:12'
const people = s.split(",")
.map(e => {
const [name, age] = e.split(":");
return {name, age};
});
console.log(people);
...or in ES5:
var s = 'Jack:13,Phil:15,Lucy:12'
var people = s.split(",")
.map(function(e) {
var parts = e.split(":");
return {name: parts[0], age: parts[1]};
});
console.log(people);
You can split() the string and use map() to loop thru the array. This will return an array of objects.
var s = 'Jack:13,Phil:15,Lucy:12';
var result = s.split(',').map(o => {
let [k, v] = o.split(':');
return {[k]: v};
});
console.log(result);
If you want a single object, you can use reduce
var s = 'Jack:13,Phil:15,Lucy:12';
var result = s.split(',').reduce((c, o) => {
let [k, v] = o.split(':');
return Object.assign(c, {[k]: v});
}, {});
console.log(result);
You can try with:
const result = s.split(',')
.map(value => value.split(':'))
.reduce((acc, [name, value]) => {
acc[name] = +value;
return acc;
}, {});
Output:
{
"Jack": 13,
"Phil": 15,
"Lucy": 12
}
As I'm sure you've worked out there are many ways to do this, I thought I'd add another method
let s = 'Jack:13,Phil:15,Lucy:12'
let obj = {};
s.split(",").forEach(part => {
obj[part.split(":")[0]] = part.split(":")[1];
})
console.log(obj);
This is a simple split the string and then on each item of the new array do a split and push the results into an empty object already declared.
You could split the parts and build a new object with key/value pairs.
var string = 'Jack:13,Phil:15,Lucy:12',
result = Object.assign(...string
.split(',')
.map(s => (([k, v]) => ({ [k]: v }))(s.split(':')))
);
console.log(result);
For getting an array with objects
var string = 'Jack:13,Phil:15,Lucy:12',
result = string
.split(',')
.map(s => (([name, age]) => ({ name, age }))(s.split(':')));
console.log(result);
Easy to do with .map():
var s = 'Jack:13,Phil:15,Lucy:12';
var items = s.split(',')
.map((entry) => entry.split(':'))
.map((item) => ({name: item[0], age: item[1]}));
console.log(items);

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