Assign object of proprieties to an other exiting object with the same proprieties

Question

I would like to assign the first object to the second object that have the same properties. What you suggest as quick method? Do I need to loop over the stores object separately?

1st object:

{
  title: 'test',
  description: 'desc',
  tags: ['tag1','tag2']
}

2nd object:

{
 title: '',
 description: '',
 tags: [],
 stores: [
    {
        id: 1,
        title: '',
        description: '',
        tags: '',
        template: '',
        link: '',
        active: true
    },
    {
        id: 2,
        title: '',
        description: '',
        tags: '',
        template: '',
        link: '',
        active: false
    }
 ]
}

Results:

{
 title: 'test',
 description: 'desc',
 tags: ['tag1', 'tag2'],
 stores: [
    {
        id: 1,
        title: 'test',
        description: 'desc',
        tags: '['tag1', 'tag2']',
        template: '',
        link: '',
        active: true
    },
    {
        id: 2,
        title: 'test',
        description: 'desc',
        tags: '['tag1', 'tag2']',
        template: '',
        link: '',
        active: false
    }
 ]
}

Yes, you need to loop over the `stores` array separately. There's nothing that automatically recurses this. — Barmar, Apr 09 '20 at 02:54
I don't know if there is a function in Lodash or another library that can handle that — Med, Apr 09 '20 at 02:58
You can use recursion, the only issue is the `tags` key that has a value typeof 'object' but we don't want to traverse it. Thus, I've added a check for that particular key in my answer below. Let me know if it helps. — Luís Ramalho, Apr 09 '20 at 03:13

Sohail Ashraf · Answer 1 · 2020-04-09T02:57:41.110

You could use object spread operator to shallow merge.

Try this.

let obj1 = {
    title: 'test',
    description: 'desc',
    tags: ['tag1', 'tag2']
};

let obj2 = {
    title: '',
    description: '',
    tags: [],
    stores: [
        {
            id: 1,
            title: '',
            description: '',
            tags: '',
            template: '',
            link: '',
            active: true
        },
        {
            id: 2,
            title: '',
            description: '',
            tags: '',
            template: '',
            link: '',
            active: false
        }
    ]
};

console.log({...obj2, ...obj1});

If you want to merge the deeply nested object then you could use the below approach.

let obj1 = {
    title: 'test',
    description: 'desc',
    tags: ['tag1', 'tag2']
};

let obj2 = {
    title: '',
    description: '',
    tags: [],
    stores: [
        {
            id: 1,
            title: '',
            description: '',
            tags: '',
            template: '',
            link: '',
            active: true
        },
        {
            id: 2,
            title: '',
            description: '',
            tags: '',
            template: '',
            link: '',
            active: false
        }
    ]
};

function isObject(item) {
    return (item && typeof item === 'object' && !Array.isArray(item));
}

function deepMerge(target, ...sources) {
    if (!sources.length) return target;
    const source = sources.shift();
    if (isObject(target) && isObject(source)) {
        for (const key in source) {
            if (isObject(source[key])) {
                if (!target[key]) Object.assign(target, { [key]: {} });
                mergeDeep(target[key], source[key]);
            } else {
                Object.assign(target, { [key]: source[key] });
            }
        }
    }
    return deepMerge(target, ...sources);
}

console.log(deepMerge(obj2, obj1));

Luís Ramalho · Answer 2 · 2020-04-09T03:17:40.507

You probably want some kind of recursive function to go through all the keys and check if they exist on the other object, something like:

let a = {
  title: "test",
  description: "desc",
  tags: ["tag1", "tag2"],
};

let b = {
  title: "",
  description: "",
  tags: [],
  stores: [{
      id: 1,
      title: "",
      description: "",
      tags: "",
      template: "",
      link: "",
      active: true,
    },
    {
      id: 2,
      title: "",
      description: "",
      tags: "",
      template: "",
      link: "",
      active: false,
    },
  ],
};

const merge = (a, b) => {
  Object.keys(b).forEach((key) => {
    if (typeof b[key] === "object" && key !== 'tags') {
      merge(a, b[key]);
    }

    if (Object.keys(a).includes(key)) {
      b[key] = a[key];
    }
  });
};

merge(a, b);

console.log(b);

console.log(b.stores[0].tags); // [ 'tag1', 'tag2' ]

I had to add a check for the case of the key tags which even though is an object, we don't want to go deeper into it. Nonetheless, this should point you in the right direction.

I already done a similar function but thank you for the direction. — Med, Apr 09 '20 at 03:13

score 0 · Answer 3 · answered Apr 09 '20 at 02:51

let obj = {
  title: 'test',
  description: 'desc',
  tags: ['tag1','tag2']
};

let obj2 = {
 title: '',
 description: '',
 tags: [],
 stores: [
    {
        id: 1,
        title: '',
        description: '',
        tags: '',
        template: '',
        link: '',
        active: true
    },
    {
        id: 2,
        title: '',
        description: '',
        tags: '',
        template: '',
        link: '',
        active: false
    }
 ]
}

console.log(Object.assign(obj2, obj))

Just using Object.assign, and flip between two object as parameter will do

This only assigns to the top-level object, not the `stores` array. — Barmar, Apr 09 '20 at 02:51

Assign object of proprieties to an other exiting object with the same proprieties

3 Answers3