How to find objects in array where inner array might include other objects by using lodash

Question

I have the following arrays:

const tasks = [
  {id: 0, name: 'a', tags: [{id: 0, name: 'q'}, {id: 1, name: 'w'}]},
  {id: 1, name: 'b', tags: [{id: 2, name: 'e'}, {id: 4, name: 't'}, {id: 11, name: 's'}]},
  {id: 2, name: 'c', tags: []},
  {id: 3, name: 'd', tags: [{id: 0, name: 'q'}, {id: 3, name: 'r'}, {id: 7, name: 'i'}]},
  {id: 6, name: 'g', tags: [{id: 7, name: 'i'}, {id: 4, name: 't'}]},
]

const tags = [
  {id: 0, name: 'q'},
  {id: 1, name: 'w'},
  {id: 2, name: 'e'},
  {id: 3, name: 'r'},
  {id: 4, name: 't'},
  {id: 7, name: 'i'},
  {id: 11, name: 's'}
]

let selectedTags = [0, 5]

selectedTags is an Array of indexes of tags Array. Now I need to find all objects in tasks Array, where property tags includes any of the selected tags. So in this case the output should be:

let result = [
  {id: 0, name: 'a', tags: [{id: 0, name: 'q'}, {id: 1, name: 'w'}]},
  {id: 3, name: 'd', tags: [{id: 0, name: 'q'}, {id: 3, name: 'r'}, {id: 7, name: 'i'}]},
  {id: 6, name: 'g', tags: [{id: 7, name: 'i'}, {id: 4, name: 't'}]}
]

I tried to do something like this:

let result= []
_.forEach(selectedTags, index => {
  const tagId = tags[index].id
  result = _.filter(tasks, task => _.some(task.tags, ['tag.id', tagId]))
})

but I'm ending up with an empty array. I tried to use map, find and some other lodash methods, but so far nothing worked.

Any ideas, please?

You're overwriting result each time through the _.forEach loop, not combining the results from previous iterations. — Barmar
– Barmar, Commented Feb 29, 2020 at 17:59

Ele · Accepted Answer · 2020-02-29 18:43:17Z

1

You're reassigning the filtered array in each iteration, also you're passing to the function .some an array, however, you should pass a key-value object instead.

The following approach used two nested calls of function .some for checking tags.id vs selectedTag ids,

const tasks = [  {id: 0, name: 'a', tags: [{id: 0, name: 'q'}, {id: 1, name: 'w'}]},  {id: 1, name: 'b', tags: [{id: 2, name: 'e'}, {id: 4, name: 't'}, {id: 11, name: 's'}]},  {id: 2, name: 'c', tags: []},  {id: 3, name: 'd', tags: [{id: 0, name: 'q'}, {id: 3, name: 'r'}, {id: 7, name: 'i'}]},  {id: 6, name: 'g', tags: [{id: 7, name: 'i'}, {id: 4, name: 't'}]}],
      tags = [  {id: 0, name: 'q'},  {id: 1, name: 'w'},  {id: 2, name: 'e'},  {id: 3, name: 'r'},{id: 4, name: 't'},  {id: 7, name: 'i'},  {id: 11, name: 's'}],
      selectedTags = [0, 5],
      result = _.filter(tasks, ({tags: itags}) => _.some(itags, ({id}) => _.some(selectedTags, i => tags[i].id === id)));

console.log(result);

.as-console-wrapper {min-height: 100%;}

<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.15/lodash.core.min.js"></script>

edited Feb 29, 2020 at 18:43

answered Feb 29, 2020 at 18:08

Ele

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5 Comments

Barmar Over a year ago

You need to remove duplicates from the result, it's returning ID:3 twice.

Igal Over a year ago

First of all thank you for your help! Much appreciated! Why did it return also object with ID 1? It doesn't have any of the selected tags

Ele Over a year ago

@Igal weird, with the destructuring assignment it generates that result, I updated the answer removing destructuring assignment.

Igal Over a year ago

@Ele Thank you very much! This time it worked as expected! BTW, your very first solution also worked, I just added result = _.uniqBy(result, 'id'). But the last solution is much cleaner! Again, thank you very much!

Ele Over a year ago

@Igal I saw the problem, it's because of the variable tags.

Maheer Ali · Accepted Answer · 2020-02-29 18:01:41Z

0

You need to use filter() with nested some()

const tasks = [
  {id: 0, name: 'a', tags: [{id: 0, name: 'q'}, {id: 1, name: 'w'}]},
  {id: 1, name: 'b', tags: [{id: 2, name: 'e'}, {id: 4, name: 't'}, {id: 11, name: 's'}]},
  {id: 2, name: 'c', tags: []},
  {id: 3, name: 'd', tags: [{id: 0, name: 'q'}, {id: 3, name: 'r'}, {id: 7, name: 'i'}]},
  {id: 6, name: 'g', tags: [{id: 7, name: 'i'}, {id: 4, name: 't'}]},
]

const tags = [
  {id: 0, name: 'q'},
  {id: 1, name: 'w'},
  {id: 2, name: 'e'},
  {id: 3, name: 'r'},
  {id: 4, name: 't'},
  {id: 7, name: 'i'},
  {id: 11, name: 's'}
]

let selectedTags = [0, 5]
const res = tasks.filter(({tags}) => 
               tags.some(tag => 
                  selectedTags.some(index => tags[index].name === tag.name)
               )
            );
console.log(res)

answered Feb 29, 2020 at 18:01

Maheer Ali

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1 Comment

Barmar Over a year ago

You're returning task ID 1, which doesn't match either of the selected tags.

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