Rendering JSON API in react Using map method

Question

I am having difficulty with the syntax and the structure of JSON objects/arrays and map method. I am new to React and on an initial stage of learning.

This is the JSON file code I pasted below:

[
  {
    "cloud":"Asia",
    "availability":{
      "last15Min":"100%",
      "last24Hour":"100%"
    },
    "data_centers":[
      {
        "title":"Bombay",
        "availability":{
          "last15Min":"100%",
          "last24Hour":"100%"
        }
      },
      {
        "title":"Bombay1",
        "availability":{
          "last15Min":"100%",
          "last24Hour":"100%"
        }
      }
    ]
  },
  {
    "cloud":"Europe",
    "availability":{
      "last15Min":"100%",
      "last24Hour":"100%"
    },
    "data_centers":[
      {
        "title": "Bombay",
        "availability": {
          "last15Min": "100%",
          "last24Hour": "100%"
        }
      },
      {
        "title":"Bombay1",
        "availability":{
          "last15Min":"100%",
          "last24Hour":"100%"
        }
      }
    ]
  }
]

Here is my code so far: I want to render each field using map method. What is the correct method to do that?

In componentDidMount I am getting the response in console.log http://prntscr.com/i09rqt

  constructor(props) {
    super(props)
    this.state = {
      clouds:[]
    }
  }

  componentDidMount() {
    var url="<api url>";
    fetch(url)
      .then(response => {
        return response.json();
      }).then(d => {
          let clouds = d.map((cloudData)=>{
            return(
              <div>{cloudData}</div>
            )
        })
        this.setState({clouds: clouds});
          console.log("state", this.state.clouds)
    })
  }

  render() {
    return (
      <div>
        {
          this.state.clouds.map((cloud =>
            <th key="">
                {cloud}
            </th>
          ))
        }
      </div>
    );
  }

Swapnil · Accepted Answer · 2018-01-14 14:46:48Z

5

Previous answer is almost correct, fixing the fetch correctly will solve the problem.

componentDidMount() {
  var url = "https://demo8192935.mockable.io/mockApi";
  fetch(url)
    .then(response => {
      return response.json();
    })
    .then(d => {
      this.setState({ clouds: d });
      console.log("state", this.state.clouds)
    })
    .catch(error => console.log(error))
}

render() {
  return (
    <div>
      {
        this.state.clouds.map(((cloud, index) =>
          <th key={`${cloud.cloud}${index}`}>
            <div>
              <div>
                {cloud.cloud}
                <div>
                  {
                    cloud.data_centers.map(d => (
                      <div>
                        {d.title}
                      </div>
                    ))
                  }
                </div>
              </div>
            </div>
          </th>
        ))
      }
    </div>
  );
}

edited Jan 14, 2018 at 14:46

answered Jan 14, 2018 at 14:32

Swapnil

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2 Comments

Bhawna Over a year ago

Thank you for the answer but i want to print "data_centers" also. How can I use map inside map method

Swapnil Over a year ago

@Bhawna, I have modified the code to show how it's done. It just an example for you to show how to nest the maps. I will recommend you to separate out the components as per your need for better code readability. I guess adding anything else to this answer is out of scope of your question. Hope this solves all your problems.

Syed · Accepted Answer · 2018-01-14 14:15:20Z

4

There is no need to return a html element inside componentDidMount.

Try this:

constructor(props) {
    super(props)
    this.state = {
        clouds: []
    }
}

componentDidMount() {
    var url = "http://trust.zscaler.com.test/sample-api/third-party-monitoring/availability.json";
    fetch(url)
        .then(response => {
            this.setState({ clouds : response })
        }).catch(error => {
            console.log(error)
        })
}

render() {
    if (this.state.clouds && this.state.clouds.length > 0) {
        return (
            <div>
                {
                    this.state.clouds.map((items =>
                        <th key="">
                            {items.cloud}
                        </th>
                    ))
                }
            </div>
        );
    }

    return null;

}

Hope this helps you.

answered Jan 14, 2018 at 14:15

Syed

2692 silver badges8 bronze badges

3 Comments

Bhawna Over a year ago

I am getting this Typeerror this.state.clouds.map is not a function

Syed Over a year ago

i have update the code by adding if statement inside render function. please take latest code and check again.

Bhawna Over a year ago

Thank you for the answer but i want to print "data_centers" also. How can I use map inside map method –

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