Iterating over multiple arrays in JSON object in React

Question

I've been trying to return the first object of the first array in my JSON object, but I'm having some trouble.

I want to return the name of the first "vitamins", which is "Vitamin B2", in an tag.

Here is my JSON object

{
  "nutrients": {
    "vitamins": [{
      "name": "Vitamin B2",
      "current": "1.7"
    },
    {
      "name": "Vitamin B6",
        "current": "10.9"
    }],
      "minerals": [{
        "name": "Zinc",
        "current": "1.7"
    }]
  }
}

And here is my code trying to map over it

import nutrients from '../../vitamins.json';

renderData() {
  return Object.keys(nutrients).map((nutrient, index) => {
    console.log('it works', nutrient[0].name, index);
    return (
      <option value="" key={index}>{nutrient[0].name}</option>
    )
  }
)}

You need to parse that JSON into a real JS object before doing any manipulation on it. — Thomas Hennes
– Thomas Hennes, Commented May 22, 2018 at 5:13

Akhil Aravind · Accepted Answer · 2018-05-22 04:52:03Z

1

var a ={
  "nutrients": {
    "vitamins": [{
      "name": "Vitamin B2",
      "current": "1.7"
    },
    {
      "name": "Vitamin B6",
        "current": "10.9"
    }],
      "minerals": [{
        "name": "Zinc",
        "current": "1.7"
    }]
  }
}

console.log(a.nutrients['vitamins'][0].name)

answered May 22, 2018 at 4:52

Akhil Aravind

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2 Comments

John White Over a year ago

Great, this works. Thanks. Now what if I want to return all of the names? If I do console.log(micros.nutrients['vitamins'].name), I get "undefined".

Akhil Aravind Over a year ago

a.nutrients['vitamins'].forEach(item =>{ console.log(item.name) });

Erick · Accepted Answer · 2018-05-22 04:56:06Z

0

Assuming the entire object to be in state.data

`render(){
 const {vitamins}=this.state.data.nutrients;
 vitamins.map((item,index)=>{
     if(index === 0)
     {    return (<div>item.name</div>)
     }`
  })
 }`

the output will print Vitamin-B2

answered May 22, 2018 at 4:56

Erick

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4 Comments

John White Over a year ago

Thanks a lot, this helped.

John White Over a year ago

The reason why you wrapped {vitamins} in a curly brace in const {vitamins} is because it's the name of an object, so it has to be wrapped in {}?

Erick Over a year ago

@bigjohnjr it is an ES6 shorthand.

Erick Over a year ago

const {vitamins} =this.state.data.nutrients when expanded becomes this.state.data.nutrients.vitamins. It's the same thing but it helps in code clarity and ease of understanding.

Raeesaa · Accepted Answer · 2018-05-22 05:01:52Z

You could use logic something like below:

let nutrientObj = {
  "nutrients": {
    "vitamins": [{
      "name": "Vitamin B2",
      "current": "1.7"
    },
    {
      "name": "Vitamin B6",
        "current": "10.9"
    }],
      "minerals": [{
        "name": "Zinc",
        "current": "1.7"
    }]
  }
}

let nutrients = nutrientObj.nutrients;
let firstElement = nutrients[Object.keys(nutrients)[0]];

console.log(firstElement && firstElement.length ? firstElement[0].name : "")

Jeeva · Accepted Answer · 2018-05-22 07:14:04Z

You may use destructuring in ES6, use this as reference https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Destructuring_assignment#Array_destructuring

import nutrients from '../../vitamins.json'
renderData() {
  const { nutrients: { vitamins: [{ name: vitaminName }] }  } = nutrients; //it destructures the given object, it will directly fetch the vitamin B2.
  console.log("Vitamin Name is = "+vitaminName)
  <option value="">{vitaminName}</option>
}

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