What is the best way to iterate over an array of objects using v-for in Vue.js?

Question

What is the best way to iterate over an array of objects using v-for in Vue.js?

Having trouble looping through this array of objects. Everything seems fine but the data is not showing up on the console.

{
 "messages":[
  {
    "id":1,
    "sender":"frank",
    "message":"Lorem ipsum...",
    "time":1398894261,
    "status":"read"
  },
  {
    "id":2,
    "sender":"mary",
    "message":"Lorem ipsum...",
    "time":1390824261,
    "status":"read"
  },
  {
    "id":3,
    "sender":"john",
    "message":"Lorem ipsum...",
    "time":1308744200,
    "status":"unread"
  }
 ]
}

Struggling to iterate through the data received from an http get request. The data is being fetched but not being looped. Below is the JavaScript code:

new Vue({
    el: '#app',
    data: '',
    ready: function() {
      // GET request
      this.$http.get('https://www.example.com/file.json', function (data) {
        // set data on vm
        this.$set('data', data.messages);
        }).error(function (data, status, request) {
            console.log('http request error')
        })
    }
  })

Here is the corresponding HTML:

<div v-if="data">
  <li v-for="d in data">{{ d.sender }}</li>
</div>
<p>{{data[0].sender}}</p> <!-- this part works -->

javascript arrays json vue.js

Answer 1

Answer №1

When dealing with the callback of an AJAX request, remember that `this` is NOT referring to the Vue instance. There are a few ways to address this issue:

Using arrow functions
Declaring `var vm = this`
Using `.bind(this)`

Check out this example on how to use arrow functions: https://codepen.io/iampaul83/pen/bYpqgm

Using arrow function:

new Vue({
    el: '#app',
    data: '',
    ready: function () {
        // Making a GET request
        this.$http.get('https://www.example.com/file.json', (data) => {
            // Setting the data on vm
            this.$set('data', data.messages);
        }).error(function (data, status, request) {
            console.log('HTTP request error')
        })
    }
})

Declaring `var vm = this`:

new Vue({
    el: '#app',
    data: '',
    ready: function () {
        // Making a GET request
        var vm = this
        this.$http.get('https://www.example.com/file.json', function (data) {
            // Setting the data on vm
            vm.$set('data', data.messages);
        }).error(function (data, status, request) {
            console.log('HTTP request error')
        })
    }
})

Using `.bind(this)`:

new Vue({
    el: '#app',
    data: '',
    ready: function () {
        // Making a GET request
        this.$http.get('https://www.example.com/file.json', function (data) {
            // Setting the data on vm
            this.$set('data', data.messages);
        }.bind(this)).error(function (data, status, request) {
            console.log('HTTP request error')
        })
    }
})

Answer 2

When dealing with the callback of an AJAX request, remember that `this` is NOT referring to the Vue instance. There are a few ways to address this issue:

Using arrow functions
Declaring `var vm = this`
Using `.bind(this)`

Check out this example on how to use arrow functions: https://codepen.io/iampaul83/pen/bYpqgm

Using arrow function:

new Vue({
    el: '#app',
    data: '',
    ready: function () {
        // Making a GET request
        this.$http.get('https://www.example.com/file.json', (data) => {
            // Setting the data on vm
            this.$set('data', data.messages);
        }).error(function (data, status, request) {
            console.log('HTTP request error')
        })
    }
})

Declaring `var vm = this`:

new Vue({
    el: '#app',
    data: '',
    ready: function () {
        // Making a GET request
        var vm = this
        this.$http.get('https://www.example.com/file.json', function (data) {
            // Setting the data on vm
            vm.$set('data', data.messages);
        }).error(function (data, status, request) {
            console.log('HTTP request error')
        })
    }
})

Using `.bind(this)`:

new Vue({
    el: '#app',
    data: '',
    ready: function () {
        // Making a GET request
        this.$http.get('https://www.example.com/file.json', function (data) {
            // Setting the data on vm
            this.$set('data', data.messages);
        }.bind(this)).error(function (data, status, request) {
            console.log('HTTP request error')
        })
    }
})

Answer 3

Answer №2

If you are encountering issues with deep reactivity limitation in vue.js, I recommend referring to the official vue documentation for guidance. Instead of utilizing this.$set, I suggest utilizing the push method to iterate through your response and add each result individually to a messages variable defined in your data object.

data.messages.forEach( (msg ) => { 
     this.messages.push( msg ); 
}

Once you have populated the messages variable, be sure to iterate through it in your template.

Answer 4

If you are encountering issues with deep reactivity limitation in vue.js, I recommend referring to the official vue documentation for guidance. Instead of utilizing this.$set, I suggest utilizing the push method to iterate through your response and add each result individually to a messages variable defined in your data object.

data.messages.forEach( (msg ) => { 
     this.messages.push( msg ); 
}

Once you have populated the messages variable, be sure to iterate through it in your template.

What is the best way to iterate over an array of objects using v-for in Vue.js?

Answer №1

Answer №2

Similar questions

Avoiding caching when making requests to /api/ routes in VueJS Progressive Web Apps (PWA

Tips for dividing an array based on a defined regex pattern in JavaScript

I possess an item, but unfortunately, I am only able to save the first object from this possession

positioning newly generated dropped elements within the DOM structure dynamically

Achieving Horizontal Alignment of Tab Labels and Icons in Material-UI with Tabs API

Completing the regex properly

Combining JWT authentication with access control lists: a comprehensive guide

Setting Json.Net as the primary serialization tool for a WCF REST service involves a few key steps

Should the Bourbon path be added to the package.json file?

Choose the value of the dynamically changing id with the same name using jQuery

What is the advantage of utilizing AngularJs .constant() over simply declaring a JavaScript const variable?

get an array of JSON data from a VueJS fetch or axios.get request

Inserting data with special characters from an Ajax POST request into a database

How can I dynamically change the default value of the selected option dropdown in React-Select when a new option is chosen?

techniques for synchronizing web service protocols and documents

Concealing the table border with the help of jQuery

Formatting dates in AngularJS

Retrieving selected values from a dynamic Primeng checkbox component

Encountering an AttributeError while attempting to write an array to a raster file with spatial attributes using the array2raster package, possibly due to

If someone installs our chat widget on their website using an <iframe> script, I would like the widget to be deactivated when our website is experiencing downtime