CODEWITHSUNDEEP
javascriptarraysreactjsobjectmap-function
Elena
Elena

Reputation: 649

Map function in react (err: TypeError: e.map is not a function)

I want to render items from props, I can do it with initial state, but not with response from server. My render function : 

 const { data } = this.props;
    return (
      <div >
          {data.map((item, index) =>
              <div key={index} className="row">
                  <span data = { data } className="number col-4 col-md-8">{item._id}</span>
                  <span data = { data } className="date col-4 col-md-2">{item.date}</span>
                  <span data = { data }  className="tag col-4 col-md-2">{item.tag}</span>
                  <div className="col-md-12 ">
                    {item.text}
                  </div>                
              </div>
          )}
      </div>
    )
  }

I get this mistake :

TypeError: e.map is not a function

response : Object {data: Array(12), status: 200, statusText: "OK", headers: Object, config: Object…}

Upvotes: 5

Views: 19916

Answers (4)

user5738822
user5738822

Reputation:

Just add these words to your map function, Because you need check if the array was existed then execute map function

const { data } = this.props;
    return (
      <div >
          {data && data.length && data.map((item, index) =>
              <div key={index} className="row">
                  <span data = { data } className="number col-4 col-md-8">{item._id}</span>
                  <span data = { data } className="date col-4 col-md-2">{item.date}</span>
                  <span data = { data }  className="tag col-4 col-md-2">{item.tag}</span>
                  <div className="col-md-12 ">
                    {item.text}
                  </div>                
              </div>
          )}
      </div>
    )
  }

Upvotes: 1

Elena
Elena

Reputation: 649

Had to change parent component change this: 

  this.setState({
    data: response
  })

to 

  this.setState({
    data: response.data
  })

I've tried to reach the data from the child component, but it din't work (probably because of the map function)

Upvotes: 3

n30n0v
n30n0v

Reputation: 24

You can use default value of data, when response is pending. In this time data is not defined

const { data = [] } = this.props;

Or use condition in  jsx:

render() {
   if (!data || !data.length) return null;
   ...
}

Upvotes: 0

Steven Scaffidi
Steven Scaffidi

Reputation: 2307

It looks like your response is just the raw response. If you're using fetch, this is what the promise chain should look like:

fetch(fromMySource).then(resp => resp.json()).then(data => doSomething(data));

It looks like you might be trying to use resp directly which would make your data array look like the response object you posted in your question.

Upvotes: 2

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