how to loop through a nested dictionary or json data in Reactjs

Question

Using Reactjs how do you create a function component that loop through the json data below and display location content.

I want the function to also be able to display something else like members if needed.

I am new to react and most examples online show it using class component (which i am not interested into)

data.json

[{
  "squadName": "Super hero squad",
  "homeTown": "Metro City",
  "formed": 2016,
  "secretBase": "Super tower",
  "active": true,
  "members": [
    {
      "name": "Molecule Man",
      "age": 29,
      "secretIdentity": "Dan Jukes",
      "powers": [
        "Radiation resistance",
        "Turning tiny",
        "Radiation blast"
      ]
    },
    {
      "authorization": "Black card",
      "location": [
        "Next",
        "Previous",
        "Here"
      ]
    }
  ]
}]

We need more details here. Can you show us your component's code? — wentjun
– wentjun, Commented Apr 22, 2020 at 12:38
@wentjun i haven't found a way to do it using functional component. thats why i asked, assuming you have to render this data in a page called ShowData that you will export to App.js — John D
– John D, Commented Apr 22, 2020 at 12:53

Ako · Accepted Answer · 2020-04-22 13:10:15Z

Of course that I cant make an entire project solution for you but the function that you wanted must have this kind of logic.

const jsonData = [{
  "squadName": "Super hero squad",
  "homeTown": "Metro City",
  "formed": 2016,
  "secretBase": "Super tower",
  "active": true,
  "members": [
    {
      "name": "Molecule Man",
      "age": 29,
      "secretIdentity": "Dan Jukes",
      "powers": [
        "Radiation resistance",
        "Turning tiny",
        "Radiation blast"
      ]
    },
    {
      "authorization": "Black card",
      "location": [
        "Next",
        "Previous",
        "Here"
      ]
    }
  ]
}]

jsonData.forEach(item=>{
  
  item.members.map((member)=>{
    
    if(member.location&&member.location[0]){
  
      //Do whatever, maybe you want to use return statement in there
      console.log(member.location)
    }
    else{
    
      //do something else, or add more conditions
      console.log("There's no location in it")
    }
  })
})

you can put it in a variable and add your variable inside your jsx return statement or use it directly in middle of your function's return statement.

Good luck.

shannon · Accepted Answer · 2020-04-22 13:23:29Z

1

You can map through data in a functional component the same way you would map through a class component. For this example, you could list only nested data:

const List = () => {
  return (
    <div>
      {data.map(item =>
        (item.members || []).map(member =>
          (member.location || []).map(item => (<div>{item}</div>))
        )
      )}
    </div>
  );
};

<script src="https://cdnjs.cloudflare.com/ajax/libs/react/16.6.3/umd/react.production.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/react-dom/16.6.3/umd/react-dom.production.min.js"></script>

which would list only the nested "location" data for each member if that property exists. Or you could map through data and display top-level properties and then also map through its nested properties:

const List = () => {
  return (
    <div>
      {data.map(item => (
        ((item.members || []).map(member => (
          <div>
            {member.name || ''}
            {member.location && member.location.map(loc => (<div>{loc}</div>))}
          </div>
        )))
      ))}
    </div>
  );
};

<script src="https://cdnjs.cloudflare.com/ajax/libs/react/16.6.3/umd/react.production.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/react-dom/16.6.3/umd/react-dom.production.min.js"></script>

edited Apr 22, 2020 at 13:23

answered Apr 22, 2020 at 12:44

shannon

3774 silver badges9 bronze badges

2 Comments

Treycos Over a year ago

You might want to run your scripts before posting them as an answer ;)

shannon Over a year ago

I did, thanks. codesandbox.io/s/romantic-black-ykrlv?file=/src/List.js:474-478

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