updating value of array of object using lodash

Question

My state object is:

[
    {
        traveller1_dob: '',
        traveller1_firstName:'',
        traveller1_isPreviousTraveller: false,
        traveller1_surname:'',
        traveller1_title: ''
    },
    {
        traveller2_dob: '',
        traveller2_firstName:'',
        traveller2_isPreviousTraveller: false,
        traveller2_surname:'',
        traveller2_title: ''
    }

]

and my payload is:

{key: "traveller1_firstName", value: "ABC", index: 0}

key is the property of the object that needs to be updated
value: is the value we want to update
index: is the index of the traveller in state array

At the moment this is the way I updated:

let obj = state[payload.index];
obj[payload.key] = payload.value;

return _.unionBy(state, [obj], payload.key);

I am aware its not the best way.

Output should be:

[
    {
        traveller1_dob: '',
        traveller1_firstName:'ABC',
        traveller1_isPreviousTraveller: false,
        traveller1_surname:'',
        traveller1_title: ''
    },
    {
        traveller2_dob: '',
        traveller2_firstName:'',
        traveller2_isPreviousTraveller: false,
        traveller2_surname:'',
        traveller2_title: ''
    }

]

Ideally I want to get rid of index if it's possible.How would you do this?

I guess a simple operation like this would do data[payload.index][payload.key] = payload.value; not much different from what you did earlier but it is better since it is able to do it in one step. — user93
– user93, Commented Sep 28, 2017 at 2:27
but if you want to do it point free form without variables you could libraries like ramdajs instead of lodash to do so like this jsfiddle.net/cdxaefvg — user93
– user93, Commented Sep 28, 2017 at 2:32
If you notice I manipulated the state obj directly as well. which i not a good idea — Negin Basiri
– Negin Basiri, Commented Sep 28, 2017 at 2:32
What's the point of an array of objects when the individual objects have uniquely numbered property names? Wouldn't it make more sense for both objects to have the same (un-numbered) properties, and then reference traveler 1 or 2 by its array index? — nnnnnn
– nnnnnn, Commented Sep 28, 2017 at 2:53

Guillermo Moratorio · Accepted Answer · 2017-09-28 16:38:28Z

4

You're right, you can get rid of the index, and just map over your state and check hasOwnProperty on each stateItem and compare them to the payload.key. The snippet below should solve your problem:

let state = [{
        traveller1_dob: '',
        traveller1_firstName: '',
        traveller1_isPreviousTraveller: false,
        traveller1_surname: '',
        traveller1_title: ''
    }, {
        traveller2_dob: '',
        traveller2_firstName: '',
        traveller2_isPreviousTraveller: false,
        traveller2_surname: '',
        traveller2_title: ''
    }

];


function updateState(payload) {

    const updatedState = _.map(state, stateItem => {
        if (stateItem.hasOwnProperty(payload.key)) {
            stateItem[payload.key] = payload.value;
        }
        return stateItem;
    });

    console.log(updatedState);
    return updatedState;
}

const samplePayload = {
    key: "traveller1_firstName",
    value: "ABC",
    index: 0
};

updateState(samplePayload);

<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.4/lodash.js"></script>

answered Sep 28, 2017 at 16:38

Guillermo Moratorio

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1 Comment

Negin Basiri Over a year ago

Thank! I like your answer because its flat structure that having object of objects which was recommended by others.

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