1

i tried to get the length of my Json response but it doesn't work i used "length" with my json result this is what i tried in my class in react js : 

  componentDidMount() {
    axios.get(`http://localhost:51492/api/CommentSurExperience/GetAllCommentOfExperience/${this.props.passedVal}`)
      .then(res => {
        const persons = res.data;
        const longeur = res.length;
        this.setState({ persons, longeur });
      })
  }

then i returned this : 

<div> <p> { this.state.longeur}</p> </div>

but i got an empty result .

how can i count how many elements in my JSON response , please thank you for your help.

**********update*********** this is my JSON result using postman enter image description here

and this is a capture showing what console.log(res) shows

enter image description here

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15
  • 1
    Could you show a sample of what res looks like? Commented Aug 16, 2018 at 13:49
  • Looks like res is a json object and not an array Commented Aug 16, 2018 at 13:52
  • @ChrisR i updated my post with a capture of Json result Commented Aug 16, 2018 at 13:53
  • 1
    could you write here result of console.log(res) ? Commented Aug 16, 2018 at 13:54
  • 1
    thats a postman api call, can you console.log(res)? Commented Aug 16, 2018 at 13:55

3 Answers 3

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10

it should be 

const longeur = res.data.length;
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1 Comment

that made it work , i just forgot the "data" , thank you so much
3

You need to use res.data.length. You can see the response schema in Axios docs.

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1 Comment

that made it work , i just forgot the "data" , thank you so much
-2

You have to specify which key in your state that number belongs to:

setState({
  persons: res.data,
  longeur: longeur
})

Else it might be because it's res.data.length that you want?

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3 Comments

This notation this.setState({ persons, longeur }); specifies the key in an implicit way.
"res.data.length " made it work , i just forgot the "data" , thank you so much
Well, yes. But he has not really specified what his state variables are called.

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