The data variable is typically implemented as ob when it is being returned

Question

The data variable is typically implemented as ob when it is being returned

Currently, I am working on creating a line chart using vue-chart.js.

Here is the Vue component I am utilizing:

  Vue.component("line-plot", {
        extends: VueChartJs.Line,
        props: ["label", "data", "options"],
        mounted(){
                fetch('api/data/monthlypaid')
                    .then(response => response.json()
                    .then(data =>{this.data = data;
                                  console.log(data);
                                  console.log(this.data); #replacing the statement above 
                                  }));
                this.renderLineChart();
        }, 
        methods:{
                renderLineChart: function () {
                    this.renderChart({
                        labels: this.data["DateReceived"],
                        datasets: [{
                            data: this.data ? this.data["AmountPaid"] : []
                                   }]

                        },
                        this.options )}
        },
        watch: {data: function () {
                          if (this._chart) {
                             this._chart.destroy();
                          }
                          this.renderLineChart();
                      }
        }
})

Following that, I set up my Vue app instance with chart options. However, an issue arose regarding the API data retrieval process. After fetching the data, when checking this.data in two console.log statements, one displays the desired JSON output while the other presents an __ob__. Is there any insight on how to ensure that this.data actually contains the JSON data obtained from the API call?

javascript vue.js vuejs2

Answer 1

Answer №1

Stop overwriting a prop and not utilizing it! Remember, manipulating props in your vue component is not recommended. Instead, create a separate data property with a different name:

 Vue.component("line-plot", {
        extends: VueChartJs.Line,
        props: ["label", "data", "options"],
        data(){
            return {
                 newData = this.data
                 // You can now make changes to this.newData
            }
        },
        mounted(){
                fetch('api/data/monthlypaid')
                    .then(response => response.json()
                    .then(data =>{this.newData = data;
                                  console.log(data);
                                  console.log(this.newData); #replacing the statment above 
                                  }));
                this.renderLineChart();
        }, 
        watch: {newData: function () {
                          if (this._chart) {
                             this._chart.destroy();
                          }
                          this.renderLineChart();
                      }
        }
})

Answer 2

Stop overwriting a prop and not utilizing it! Remember, manipulating props in your vue component is not recommended. Instead, create a separate data property with a different name:

 Vue.component("line-plot", {
        extends: VueChartJs.Line,
        props: ["label", "data", "options"],
        data(){
            return {
                 newData = this.data
                 // You can now make changes to this.newData
            }
        },
        mounted(){
                fetch('api/data/monthlypaid')
                    .then(response => response.json()
                    .then(data =>{this.newData = data;
                                  console.log(data);
                                  console.log(this.newData); #replacing the statment above 
                                  }));
                this.renderLineChart();
        }, 
        watch: {newData: function () {
                          if (this._chart) {
                             this._chart.destroy();
                          }
                          this.renderLineChart();
                      }
        }
})

Answer 3

Answer №2

It is my understanding that the __ob__: Observer plays a crucial role in Vue's reactivity mechanism. If you are unable to see your API's response data next to the observer, it indicates that there has been no update to your this.data.

From what I gather, it appears that you are attempting to assign a value to this.data from a prop, which suggests that your parent component may be altering this.data. My recommendation would be to create a separate variable in your "line-plot" component, assign it the value of this.data, and then work with this new variable instead:

data() {
    return {data2: this.data}}
},watch: {data2: function () {
    ...
}

Furthermore, rather than relying on console logging, I recommend installing the Vue Devtool extension for your browser. This tool allows you to inspect the values of your variables easily. https://chrome.google.com/webstore/detail/vuejs-devtools/nhdogjmejiglipccpnnnanhbledajbpd?hl=en

Answer 4

It is my understanding that the __ob__: Observer plays a crucial role in Vue's reactivity mechanism. If you are unable to see your API's response data next to the observer, it indicates that there has been no update to your this.data.

From what I gather, it appears that you are attempting to assign a value to this.data from a prop, which suggests that your parent component may be altering this.data. My recommendation would be to create a separate variable in your "line-plot" component, assign it the value of this.data, and then work with this new variable instead:

data() {
    return {data2: this.data}}
},watch: {data2: function () {
    ...
}

Furthermore, rather than relying on console logging, I recommend installing the Vue Devtool extension for your browser. This tool allows you to inspect the values of your variables easily. https://chrome.google.com/webstore/detail/vuejs-devtools/nhdogjmejiglipccpnnnanhbledajbpd?hl=en

Answer 5

Answer №3

After taking @Ahmad's advice into consideration, I realized that manipulating component props within the component itself is not a recommended practice. However, this wasn't the issue I was facing. My problem turned out to be much simpler than that.

The Line chart I am working with is based on the chartjs library, which requires the labels and data within the dataset to be in array format. Unfortunately, my API was providing data in JSON object format, causing 'Vuejs' to convert it to an __ob__.

To resolve this issue, I had two options: either modify the output of the API (which I did), or iterate through the object structure resembling something like {0:200, 1:455, ..., 20:90}. This can be achieved using the following function:

var group = {0:200, 1:455, 2:44, 3:355, 20:90}; // example of object structure
var dt = [];
var numbers = Object.keys(group);
numbers.forEach(function(number) {
  var item = Object.values(group[person]);
  dt.push(item);
});
return dt;

By implementing this approach, the dt array becomes compatible with the requirements of chartjs.

Answer 6

After taking @Ahmad's advice into consideration, I realized that manipulating component props within the component itself is not a recommended practice. However, this wasn't the issue I was facing. My problem turned out to be much simpler than that.

The Line chart I am working with is based on the chartjs library, which requires the labels and data within the dataset to be in array format. Unfortunately, my API was providing data in JSON object format, causing 'Vuejs' to convert it to an __ob__.

To resolve this issue, I had two options: either modify the output of the API (which I did), or iterate through the object structure resembling something like {0:200, 1:455, ..., 20:90}. This can be achieved using the following function:

var group = {0:200, 1:455, 2:44, 3:355, 20:90}; // example of object structure
var dt = [];
var numbers = Object.keys(group);
numbers.forEach(function(number) {
  var item = Object.values(group[person]);
  dt.push(item);
});
return dt;

By implementing this approach, the dt array becomes compatible with the requirements of chartjs.

The data variable is typically implemented as ob when it is being returned

Answer №1

Answer №2

Answer №3

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The data variable is typically implemented as __ob__ when it is being returned

Answer №1

Answer №2

Answer №3

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The data variable is typically implemented as ob when it is being returned