Map over nested array of objects in React

Question

I am trying to map over array of objects which each array contains another nested array of objects. However, the map does not work on the nested array. How do I map over the contents of the nested array while keeping all the content under the same title of the parent object?

Fiddle: https://jsfiddle.net/69z2wepo/249197/

The data structure looks like:

[
  {
    title: "title1",
    content: [
      {
        imageUrl: "http://placehold.it/300x300",
        title: "Campaigns",
        description:
          "Short description explaining the use of this design in a single sentence."
      },
      {
        imageUrl: "http://placehold.it/300x300",
        title: "Events",
        description:
          "Short description explaining the use of this design in a single sentence."
      },
      {
        imageUrl: "http://placehold.it/300x300",
        title: "General",
        description:
          "Short description explaining the use of this design in a single sentence."
      }
    ]
  },
  {
    title: "title2",
    content: [
      {
        imageUrl: "http://placehold.it/300x300",
        title: "Video Template A",
        description:
          "Short description explaining the use of this design in a single sentence."
      },
      {
        imageUrl: "http://placehold.it/300x300",
        title: "Video Template A",
        description:
          "Short description explaining the use of this design in a single sentence."
      }
    ]
  }
];

The map looks like

{dataItems.map((item, index) => {
  return (
    <h1>{item.title}</h1>
    // for each item, loop over the content array objects
    <img src={item.content.imageUrl} />
    <h3>{item.content.title}</h3>
    <h3>{item.content.description}</h3>
    <hr />
  );
})}

I think you just need `item.content.map((content, index) => ...)` — ionizer, Jul 31 '18 at 14:20

score 30 · Accepted Answer · answered Jul 31 '18 at 14:23

Since each element has a content array, you must map over content as well.

Example

{dataItems.map((item, index) => (
  <div key={index}>
    <h1>{item.title}</h1>
    {item.content.map((c, i) => (
      <div key={i}>
        <img src={c.imageUrl} />
        <h3>{c.title}</h3>
        <h3>{c.description}</h3>
        <hr />
      </div>
    ))}
  </div>
))}

score 8 · Answer 2 · answered Jul 31 '18 at 14:30

This is a working example.

const dataItems = [{
    title: "title1",
    content: [{
        imageUrl: "http://placehold.it/300x300",
        title: "Campaigns",
        description: "Short description explaining the use of this design in a single sentence."
      },
      {
        imageUrl: "http://placehold.it/300x300",
        title: "Events",
        description: "Short description explaining the use of this design in a single sentence."
      },
      {
        imageUrl: "http://placehold.it/300x300",
        title: "General",
        description: "Short description explaining the use of this design in a single sentence."
      }
    ]
  },
  {
    title: "title2",
    content: [{
        imageUrl: "http://placehold.it/300x300",
        title: "Video Template A",
        description: "Short description explaining the use of this design in a single sentence."
      },
      {
        imageUrl: "http://placehold.it/300x300",
        title: "Video Template A",
        description: "Short description explaining the use of this design in a single sentence."
      }
    ]
  }
];

class App extends React.Component {
  render() {
    return <div> 
    {
      dataItems.map((item, index) => {
        return ( <div>
            <h1>{item.title}</h1>
            { item.content.map((c, i) => <div>
            <h3>{c.title}</h3>
            <h3>{c.description}</h3>
            </div>)}
          </div>
        )
      })
    }
    </div>
  }
}

ReactDOM.render( < App / > , document.getElementById('root'));

<div id="root"></div>
<script src="https://cdnjs.cloudflare.com/ajax/libs/react/15.1.0/react.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/react/15.1.0/react-dom.min.js"></script>

Map over nested array of objects in React

2 Answers2

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