Lodash create new array from selected keys

Question

My prop data is outputed as:

const { profile } = this.props;
console.log("help", profile);

{notes: "", name: "John", gender: "M", dob: "", age: "33", nationality: "British", notes2: "no notes", notes3: "no notes"}

I want to be able to pull out the notes and end up with something like this:

{notes: "", notes2: "no notes", notes3: "no notes"}

I need to keep "profile" as its own prop so would need to create a const to store this output.

I tried something like this:

const oldArray = _.map(_.toPairs(profile), d => _.fromPairs([d]));
const newArray = _.map(oldArray => [{notes: notes}, {notes: notes2}, {notes: notes3}]);

The reason I want to do this is to then run a check to see if all notes are empty, but cant do this whilst they sit in the array with lots of different keys.

Answer 1

If you have an object you could use _.pick method and return a new object with specific properties.

 const obj = {notes: "", name: "John", gender: "M", dob: "", age: "33", nationality: "British", notes2: "no notes", notes3: "no notes"} const notes = _.pick(obj, ['notes', 'notes2', 'notes3']); console.log(notes) 

 <script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.10/lodash.js"></script> 

Answer 2

You can loop through the keys of that object and check if the key has notes as a substring. If yes then add that key-value to a new object. Using this you do not need to worry about keys like notes1 , notes2 , notes3 , ... and so on. You can simply check for the substring notes :

 var obj = {notes: "", name: "John", gender: "M", dob: "", age: "33", nationality: "British", Notes2: "no notes", notes3: "no notes"}; var res = {}; Object.keys(obj).forEach((key) => { if(key.toLowerCase().indexOf('notes') !== -1){ res[key] = obj[key]; } }); console.log(res); 

Answer 3

You can use plain js instead of lodash:

const { profile } = this.props;
const { notes, notes2, notes3 } = profile;
const newObject  = { notes, notes2, notes3 };

Then you can check the values:

const hasValues = Object.values(newObject).filter(v => !!v).length > 0;

Answer 4

Use _.pickBy() with String.startsWith() (or lodash's equivalent ) to find all the keys that start with the word notes :

 const props = {notes: "", name: "John", gender: "M", dob: "", age: "33", nationality: "British", notes2: "no notes", notes3: "no notes"}; const notes = _.pickBy(props, (v, k) => k.startsWith('notes')); console.log(notes) 

 <script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.10/lodash.js"></script>