javascript - Using promises in Axios requests - Stack Overflow

I am trying to work out the best way to achieve something. When I land on a Profile page, the Profile ponent loads the data for that profile. This is assigned to this.profile. Within this data is a path to a file, where I want to process some data using this file. To me, the below approach seems slightly risky.

created() {
    let vm = this;

    let url = `/api/profile/${this.$route.params.id}`;
    axios.get(url).then(response => {
        this.profile = response.data;

        d3.json(response.data.fileName)
        .then(function (data) {
            //do some stuff

        }).catch(function (error) {
            // handle error
        });
    });
}

Instead of that, I want to ensure that I first have the data from the axios call. So I am thinking I need a promise? I was thinking something more along the lines off

created() {
    let vm = this;

    let url = `/api/profile/${this.$route.params.id}`;
    axios.get(url).then(response => {
        this.profile = response.data;
    }).then() {
        d3.json(response.data.fileName)
        .then(function (data) {
            //do some stuff

        }).catch(function (error) {
            // handle error
        });
    };
}

But the above is incorrect, it is mainly to show what I am trying to achieve. I was wondering how I can maybe use deferred and promises to only execute the d3 stuff once the axios call is made.

Thanks

I am trying to work out the best way to achieve something. When I land on a Profile page, the Profile ponent loads the data for that profile. This is assigned to this.profile. Within this data is a path to a file, where I want to process some data using this file. To me, the below approach seems slightly risky.

created() {
    let vm = this;

    let url = `/api/profile/${this.$route.params.id}`;
    axios.get(url).then(response => {
        this.profile = response.data;

        d3.json(response.data.fileName)
        .then(function (data) {
            //do some stuff

        }).catch(function (error) {
            // handle error
        });
    });
}

Instead of that, I want to ensure that I first have the data from the axios call. So I am thinking I need a promise? I was thinking something more along the lines off

created() {
    let vm = this;

    let url = `/api/profile/${this.$route.params.id}`;
    axios.get(url).then(response => {
        this.profile = response.data;
    }).then() {
        d3.json(response.data.fileName)
        .then(function (data) {
            //do some stuff

        }).catch(function (error) {
            // handle error
        });
    };
}

But the above is incorrect, it is mainly to show what I am trying to achieve. I was wondering how I can maybe use deferred and promises to only execute the d3 stuff once the axios call is made.

Thanks

• javascript
• vue.js
• vuejs2

Share Improve this question Follow asked Feb 8, 2019 at 17:10 katie hudsonkatie hudson 2,8931313 gold badges5454 silver badges101101 bronze badges 2

• All the code inside the axios.get().then() function is only going to run once the web request has returned and response has been populated. I'm not sure what the problem is here? (you're also not actually using this.profile...) – match Commented Feb 8, 2019 at 17:14
• I think d3.json() is based on callbacks and not promises. And as far I read, d3.json is to fetch something from the server and modify it as JSON. it is almost analogous to axios!! why use both ? – Dhananjai Pai Commented Feb 8, 2019 at 17:15

Add a ment  | 

3 Answers 3

Sorted by: Reset to default 2

You can solve this by chaining promises, assuming that d3.json returns a promise:

created() {
    let vm = this;
    let url = `/api/profile/${this.$route.params.id}`;
    axios.get(url)
      .then(response => {
        this.profile = response.data
        return d3.json(response.data.fileName)
      }).then(data => {
        //do some stuff
      }).catch(err => {
        //log error
      })
}

That's where async/await es in handy. A you don't need to save this to a variable and B you have cleaner, more readable code.

async created() {

    const url = `/api/profile/${this.$route.params.id}`;
    const { data } = await axios.get(url); // Optional destructuring for less clutter
    this.profile = data;

    const d3Data = await d3.json(data.fileName);
    //do whatever you want

}

async created() {
let vm = this;

let url = `/api/profile/${this.$route.params.id}`;
try {
const {data} = await axios.get(url)

const d3Data = await d3.json(data.fileName)
    } catch(err) {
      //error
    }
}