The Vue.js page loads prior to the completion of the Axios request fetching data

Question

The Vue.js page loads prior to the completion of the Axios request fetching data

Challenge

I am facing an issue while trying to fetch data from my database using vuejs + axios within a Laravel project. Locally, the axios request works fine and the data is displayed on the DOM after assigning it to variables. However, when deploying the same code to production, the axios request seems to take longer to execute, leading to a 'undefined property' error due to vuejs being ready before all the data is returned. This error persists even after multiple refreshes.

Possible Cause of the Problem

My assumption is that axios is not retrieving the data quickly enough for vuejs to display it, resulting in the undefined error.

Attempts Made so Far

I have tried using v-if statements on the objects dependent on the data, but it only hides the object if the data is not present. For example...

HTML

<!-- If user.name exists, display user.name -->
<div v-if="user.name">
    @{{ user.name }}
</div>

JAVASCRIPT

<script>
    new Vue({
        el: '#container',
        data: {
            user: {}
        },
        mounted() {
            this.getUserData();
        },
        methods: {
            getUserData(){
                axios.post('/user/get').then((response) => {

                    // Check the response was a success
                    if(response.data.status === 'success')
                    {
                        this.user = response.data.user;
                    }
                });
            },
        }
    })
</script>

However, this approach does not solve the issue and does not display anything when the data hasn't loaded yet.

Query

How can I ensure that the loaded data is displayed without encountering an undefined error? One solution I can think of is to allow the user to 'click to retrieve data' upon a failed attempt.

Additional Details

I am not using vue templates, child/parent structures, or any vue libraries. I am simply importing vue.js via CDN and using it on the page as shown above. I am uncertain if this method may have limitations, as my knowledge of vue.js is basic and this setup has been approved by my company and boss.

javascript laravel vue.js axios

Answer 1

Answer №1

To solve this issue, consider adding a boolean attribute named 'loaded'. Here is an example implementation:

<script>
    new Vue({
        el: '#container',
        data: {
            isLoaded: false,
            user: {}
        },
        mounted() {
            this.getUserData();
        },
        methods: {
            getUserData(){
                axios.post('/user/get').then((response) => {

                    this.isLoaded = true;

                    // Ensure the response was successful
                    if(response.data.status === 'success')
                    {
                        this.user = response.data.user;
                    }
                });
            },
        }
    })
</script>

Then modify your HTML to check if the data has been loaded:

<div v-if="isLoaded">
   <!-- Display user.name if it exists -->
   <div v-if="user.name">
       @{{ user.name }}
   </div>
</div>

You can also include a loader while waiting for data:

<div v-if="isLoaded">
   <!-- Display user.name if it exists -->
   <div v-if="user.name">
       @{{ user.name }}
   </div>
</div>

<div v-else>
    Loading...
</div>

Answer 2

To solve this issue, consider adding a boolean attribute named 'loaded'. Here is an example implementation:

<script>
    new Vue({
        el: '#container',
        data: {
            isLoaded: false,
            user: {}
        },
        mounted() {
            this.getUserData();
        },
        methods: {
            getUserData(){
                axios.post('/user/get').then((response) => {

                    this.isLoaded = true;

                    // Ensure the response was successful
                    if(response.data.status === 'success')
                    {
                        this.user = response.data.user;
                    }
                });
            },
        }
    })
</script>

Then modify your HTML to check if the data has been loaded:

<div v-if="isLoaded">
   <!-- Display user.name if it exists -->
   <div v-if="user.name">
       @{{ user.name }}
   </div>
</div>

You can also include a loader while waiting for data:

<div v-if="isLoaded">
   <!-- Display user.name if it exists -->
   <div v-if="user.name">
       @{{ user.name }}
   </div>
</div>

<div v-else>
    Loading...
</div>

Answer 3

Answer №2

Revised answer, providing a clearer explanation of my point.

Your code should be able to function regardless of how long it takes for axios to retrieve the data, whether it's 1 second or 10 seconds. There shouldn't be a need to use v-if to check for user.name. VueJS has reactivity built in and will automatically update the view when the data property changes.

Take a look at this example code. https://codepen.io/bergur/pen/VOXrzR

In this scenario, I deliberately wait 10 seconds to fill the user object.

{{ user.name }} initially displays nothing and then Bergur
{{ computedName }} shows undefined Hallgrímsson because user.name is undefined for 10 seconds.
{{ user.address.country }} will trigger an error (Cannot read property 'country' of undefined) as user.address is not included in the initial data object.

One solution is to define address within the data object from the start

user: {
  address: {}
}

The essence of my argument is that your original code should work during rendering. The errors occur due to:

a) Utilizing a name property in your vue app, like user.name, when there is no name property present.

or

b) Attempting to render a property on the second level, such as user.address.country, before defining address initially.

Answer 4

Revised answer, providing a clearer explanation of my point.

Your code should be able to function regardless of how long it takes for axios to retrieve the data, whether it's 1 second or 10 seconds. There shouldn't be a need to use v-if to check for user.name. VueJS has reactivity built in and will automatically update the view when the data property changes.

Take a look at this example code. https://codepen.io/bergur/pen/VOXrzR

In this scenario, I deliberately wait 10 seconds to fill the user object.

{{ user.name }} initially displays nothing and then Bergur
{{ computedName }} shows undefined Hallgrímsson because user.name is undefined for 10 seconds.
{{ user.address.country }} will trigger an error (Cannot read property 'country' of undefined) as user.address is not included in the initial data object.

One solution is to define address within the data object from the start

user: {
  address: {}
}

The essence of my argument is that your original code should work during rendering. The errors occur due to:

a) Utilizing a name property in your vue app, like user.name, when there is no name property present.

or

b) Attempting to render a property on the second level, such as user.address.country, before defining address initially.

Answer 5

Answer №3

Utilizing lodash's debounce function allows for the delay in execution when calling a method, function, or computed property. This is beneficial when differentiating between delays for various methods - for example, triggering one on mounted and another through a watcher. In my specific scenario, the function called upon mounting must wait for an axios response to set store.state.TableDataInit, while the watcher function can run immediately since the store.state variable has already been defined.

created: function() {
    this.setInitRange = _.debounce(this.setRange, 600);
    this.setInitBoundaries = _.debounce(this.setBoundaries, 600);
    this.setWatchRange = this.setRange;
    this.setWatchBoundaries = this.setBoundaries;
},
mounted() {    
    this.setInitRange(this.selected);
    this.setInitBoundaries();
},

watch: {
    selected() {      
      store.commit("storedMetric", this.selected);
      this.setWatchRange(this.selected); 
      this.setWatchBoundaries();
    }    
},
methods: {
    setRange(value) {
      var metric = value;
      var dataArray = store.state.TableDataInit; 
      const maxMetric = dataArray.reduce(function(prev, current) {
        return _.get(prev, metric) > _.get(current, metric) ? prev : current;
      })[metric];
      const minMetric = dataArray.reduce(function(prev, current) {
        return _.get(prev, metric) < _.get(current, metric) ? prev : current;
      })[metric];
      this.range = [minMetric, maxMetric];
      store.commit("storedOutBoundRange", this.range);
   },
   setBoundaries() {
      this.min = store.state.OutBoundRange[0];
      this.max = store.state.OutBoundRange[1];
    },

Answer 6

Utilizing lodash's debounce function allows for the delay in execution when calling a method, function, or computed property. This is beneficial when differentiating between delays for various methods - for example, triggering one on mounted and another through a watcher. In my specific scenario, the function called upon mounting must wait for an axios response to set store.state.TableDataInit, while the watcher function can run immediately since the store.state variable has already been defined.

created: function() {
    this.setInitRange = _.debounce(this.setRange, 600);
    this.setInitBoundaries = _.debounce(this.setBoundaries, 600);
    this.setWatchRange = this.setRange;
    this.setWatchBoundaries = this.setBoundaries;
},
mounted() {    
    this.setInitRange(this.selected);
    this.setInitBoundaries();
},

watch: {
    selected() {      
      store.commit("storedMetric", this.selected);
      this.setWatchRange(this.selected); 
      this.setWatchBoundaries();
    }    
},
methods: {
    setRange(value) {
      var metric = value;
      var dataArray = store.state.TableDataInit; 
      const maxMetric = dataArray.reduce(function(prev, current) {
        return _.get(prev, metric) > _.get(current, metric) ? prev : current;
      })[metric];
      const minMetric = dataArray.reduce(function(prev, current) {
        return _.get(prev, metric) < _.get(current, metric) ? prev : current;
      })[metric];
      this.range = [minMetric, maxMetric];
      store.commit("storedOutBoundRange", this.range);
   },
   setBoundaries() {
      this.min = store.state.OutBoundRange[0];
      this.max = store.state.OutBoundRange[1];
    },

Answer 7

Answer №4

<div v-if="customer">
   <div>
       @{{ customer.firstname }}
   </div>
   <div>
       @{{ customer.lastname }}
   </div>
   <div>
       @{{ customer.email }}
   </div>
   <div>
       @{{ customer.address }}
   </div>
</div>

Answer 8

<div v-if="customer">
   <div>
       @{{ customer.firstname }}
   </div>
   <div>
       @{{ customer.lastname }}
   </div>
   <div>
       @{{ customer.email }}
   </div>
   <div>
       @{{ customer.address }}
   </div>
</div>

The Vue.js page loads prior to the completion of the Axios request fetching data

Answer №1

Answer №2

Answer №3

Answer №4

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