How to add one parameter to every object in array?

Question

so i have some cases.

Add category to every object in array, which holds in state

Posts, are array of object ( these object are wordpress article, and have a lot of parameters)

It's holded in state:

constructor(props) {
    super(props);
    this.state = {
      posts: [],
      postCategories: [],
    };
  }

Later i getting data from other endpoints (category for every posts, from another endpoint)

      fetch(postsUrl)
        .then(data => data.json())
        .then(data => {
            this.setState({
               posts: data,
            })
            const postcategory = data.map((category) => category.categories)

            if (postcategory === 2)
            {
                console.log("category1" + postcategory)
            }
            if(postcategory === 3){
                console.log("category2" + postcategory)
            }
        })

postcategory - every category from every posts (But it's enum not string (1,2,3 etc.))

I need to add parameter to every object in array - posts depends on e.num (if posts[0] have postcategory 1 i need to inject parameter name: category, with content dependend on enum.

eg. for post[0] it's postcategory = 2 so i need to inject parameter name: category with value "category2"

Additionally, the solution should include all objects in the array - loop?

Dupocas · Accepted Answer · 2019-10-17 17:11:17Z

2

You can use map and spread to achieve this

const result = array.map(item =>{
    if(condition1)
        return {...item, newProperty: 'foo'}

    if(condition2)
       return {...item, anotherProp: 'bar'}

    return item
})

answered Oct 17, 2019 at 17:11

Dupocas

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8 Comments

Piotr Żak Over a year ago

Wow thanks, it's adding parameter to every object, now i going to try match this to my problem :)

Piotr Żak Over a year ago

Ok, i implement it to my solution and it's generally work, now i trying resolve the issue with conditions

Dupocas Over a year ago

If you want post another question!

Piotr Żak Over a year ago

if(item.categories === 2), if(item.categories === 3) These condition didn't add parameter name to every object of array

Dupocas Over a year ago

Could you post another question explaining better? Comments are just messy!

|

Svdb · Accepted Answer · 2019-10-17 17:34:38Z

1

To alter the data received from the fetch, you have to change the data inside the map function. The whole array will be returned into newPostData which you can then set in state.

fetch(postsUrl)
.then(data => data.json())
.then(data => {
  const newPostData = data.map(item => {
    if (item.categories === 2) {
      item.myNewValue = 'the new value if categories is 2';
    }
    if (item.categories === 3)
      console.log('Categories equals 3')

    return item
  }

  this.setState({posts: newPostData})
})

edited Oct 17, 2019 at 17:34

answered Oct 17, 2019 at 17:16

Svdb

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1 Comment

Dupocas Over a year ago

You're mutating the state

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