How to Utilize the Vue Instance With the 'this'

Question

How to Utilize the Vue Instance With the 'this'

Trying to implement this in my VueJs methods results in an error message:

this is undefined

It seems like arrow functions may not be suitable as their this does not bind to the expected context.

Switching to a regular function still causes the same error.

My troubleshooting attempts so far

methods: {
  connection(){
    new elasticsearch.Client({...});
    
    client.search({...})
          .then(function (resp) {
            var hits = resp.aggregations;
            this.tmp = hits[1].value;
          }, function (err) {
            console.trace(err.message);
          });                   
   }
}

The issue lies in not being able to access the desired this within the functions passed to .search and .then. How can I ensure that this is bound to my VueJs instance so I can utilize data, computed, and other properties?

javascript vue.js

Answer 1

Answer №1

To maintain the correct context of `this`, it is recommended to utilize arrow functions in Vue methods, as `this` refers to the current instance within them.

data() {
  return {
    counter:0,
    connections:2,
    tmp: 0,
  }
},
methods: {
  connection() {
    // ...
    var client = new elasticsearch.Client({
      host: 'xxxxxxxxxxxx'
    });
    client.search({
      [...]
    }).then((resp) => {
      var hits = resp.aggregations;
      this.tmp = hits[1].value;
    }, (err) => {
      console.trace(err.message);
    });
  }
}

Answer 2

To maintain the correct context of `this`, it is recommended to utilize arrow functions in Vue methods, as `this` refers to the current instance within them.

data() {
  return {
    counter:0,
    connections:2,
    tmp: 0,
  }
},
methods: {
  connection() {
    // ...
    var client = new elasticsearch.Client({
      host: 'xxxxxxxxxxxx'
    });
    client.search({
      [...]
    }).then((resp) => {
      var hits = resp.aggregations;
      this.tmp = hits[1].value;
    }, (err) => {
      console.trace(err.message);
    });
  }
}

Answer 3

Answer №2

In order to utilize the this variable within the .then function, assign it to a local variable (self) as shown below:

   data () {
    return {
        counter:0,
        connections:2
    }
},
methods: {
    connection(){
        var self = this;
        var tmp=0
        var elasticsearch = require('elasticsearch');
        var client = new elasticsearch.Client({
        host: 'xxxxxxxxxxxx'
        });
        client.search({
        "index":"400000",
        [...]
        }
        }).then(function (resp) {
            var hits = resp.aggregations;
            self.tmp=hits[1].value;
        }, function (err) {
            console.trace(err.message);
        });   
        console.log("tmp:",tmp)

    }
}

Answer 4

In order to utilize the this variable within the .then function, assign it to a local variable (self) as shown below:

   data () {
    return {
        counter:0,
        connections:2
    }
},
methods: {
    connection(){
        var self = this;
        var tmp=0
        var elasticsearch = require('elasticsearch');
        var client = new elasticsearch.Client({
        host: 'xxxxxxxxxxxx'
        });
        client.search({
        "index":"400000",
        [...]
        }
        }).then(function (resp) {
            var hits = resp.aggregations;
            self.tmp=hits[1].value;
        }, function (err) {
            console.trace(err.message);
        });   
        console.log("tmp:",tmp)

    }
}

How to Utilize the Vue Instance With the 'this'

My troubleshooting attempts so far

Answer №1

Answer №2

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