Reputation: 131

How to iterate through an array of objects from json in React.js

I am trying to loop through an array of objects in an external json file using the map function. The loop succeeds but I am not sure how to access the object properties. See below.

I am using object.keys(obj).map() but cannot get access to the individual properties. Map keeps outputting the array index numbers.

This is my data I want to iterate through.

[
   {
     "id" : "12345",
     "customer" : "BMW",
   },
   {
     "id" : "45678",
     "customer" : "Ford",
   },
   {
     "id" : "78901",
     "customer" : "Google",
   } 
]

I have a state hook that the data will be saved to

const [accountData, setAccountData] = useState('');

The function below gets the data from the external json file and sets the state with it.


 axios.get('./data/account-info.json')
  .then((response) => {
     //set state
     setAccountData(response.data);
  })
  .catch((error) => {
     console.log(error);
  });

I iterate through the state object with a map function

Object.keys(accountData).map((id,customer) => {
  return(
    <div>
      <p>ID: {id}</p>
      <p>Name: {customer}</p>
    </div>
  )
})

The output keeps printing out the index numbers instead of the appropriate values

//outputted elements

<div>
  <p>ID: 0</p>
  <p>Name: 0</p>
</div>

<div>
  <p>ID: 1</p>
  <p>Name: 1</p>
</div>

<div>
  <p>ID: 2</p>
  <p>Name: 2</p>
</div>

Can you please tell me what I am doing wrong here? I know it has to be something simple.

Upvotes: 3

Answers (5)

dance2die

Reputation: 36895

You can iterate accountData directly, as it's an array.
Each item will be an object, so you need to destructure as you see below.
(you don't need to but that's was the intention I perceived from your code)

And also you need to add a key to each element, to notify React how to keep track of elements.

//               👇 destrcuture the properties
accountData.map(({ id,customer }) => {
  return(
   {/* 👇 make sure to add keys here too */}
    <div key={id}>
      <p>ID: {id}</p>
      <p>Name: {customer}</p>
    </div>
  )
})

-- Reply to the [COMMENT] --

so whenever I remove the object.keys() it throws this error at me TypeError: accountData.map is not a function

Would you double check if response.data is as what you mentioned in the post?
If you run the code below, it will correctly print id & customer array.

let accountData = [
   {
     "id" : "12345",
     "customer" : "BMW",
   },
   {
     "id" : "45678",
     "customer" : "Ford",
   },
   {
     "id" : "78901",
     "customer" : "Google",
   } 
] 
accountData.map(({id, customer}) => console.log(id, customer))

Upvotes: 3

TopW3

Reputation: 1527

Object.keys function returns the array of its keys. For array object, its keys are its indices. So in case of your accountData, Object.keys(accountData) returns [ '0', '1', '2' ].

If you still want to use Object.keys function, you can do like this.

Object.keys(accountData).map(key => (
    <div key={accountData[key].id}>
        <p>ID: {accountData[key].id}</p>
        <p>Name: {accountData[key].customer}</p>
    </div>
));

But in case of an array, it would be better to apply map function directly to it.

accountData.map(account => (
    <div key={account.id}>
        <p>ID: {account.id}</p>
        <p>Name: {account.customer}</p>
    </div>
));

That's all.

Upvotes: 0

Jackkobec

Reputation: 6705

accountData.map(customer => {
  return(
    <div
      key={ customer.id }
     >
      <p>ID: { customer.id }</p>
      <p>Name: { customer.customer }</p>
    </div>
  )
})

Upvotes: 0