Obtaining information from AngularJS callback function in loopback: A comprehensive guide

Question

Obtaining information from AngularJS callback function in loopback: A comprehensive guide

I am trying to figure out how to retrieve the "good" array from an angular function. Here is the function I have in my Angular code:

app.run(function($rootScope,Communications,$http,$filter) {

    $rootScope.getCommunication = 
    function(object_type,val,id,isType,isSendSms,getNotes){

      var array = {};
      var newArr = [];

      // getting data from mysql data 
      var myVals = Communications.find({
            filter: {
              where: {
                and : [{
                  communications_type_code : val
                },{
                  object_id : id
                },{
                  object_type : object_type
                }]
              }
            } 
          }).$promise
            .then(function(data) {

              for(var ind=0; ind<data.length; ind++){
                array['address_type'] = data[ind].address_type;
                array['contact_value'] = data[ind].contact_value;
                array['send_sms'] = data[ind].send_sms;
              }

              newArr.push(array);
               return newArr;
            });
      return newArr;
    };
  });

When I try to call the function in my Angular controller like this:

var arr = $rootScope.getCommunication(2,3,$id);
  console.log(arr);

I see something like this in the console:

https://i.sstatic.net/qmIVV.jpg

But when I try to access arr[0], I get undefined. How can I access this data properly?

javascript angularjs loopbackjs

Answer 1

Answer №1

To ensure the proper execution of your code, it is important to return the promise instead of the array before it is updated. Asynchronous operations work by executing all synchronous code first before moving on to anything async.

var arr = []; // initialized first
promise.then(function(result){arr = result}) // executed third
return arr; // returned second

It is crucial to modify your code to return the promise. However, this also implies that your calling code must be able to handle asynchronous operations.

function asyncFunc() {
 return promise.then(function(result){return result});
}

asyncFunc().then(function(result) {console.log(result)}) // prints the value of result.

In relation to the provided code snippet above:

app.run(function($rootScope,Communications,$http,$filter) {

$rootScope.getCommunication = 
function(object_type,val,id,isType,isSendSms,getNotes){
  // retrieving data from a MySQL database
  return Communications.find({
        filter: {
          where: {
            and : [{
              communications_type_code : val
            },{
              object_id : id
            },{
              object_type : object_type
            }]
          }
        } 
      }).$promise
        .then(function(data) {
          var array = {};
          var newArray = [];
          for(var ind=0; ind<data.length; ind++){
            array['address_type'] = data[ind].address_type;
            array['contact_value'] = data[ind].contact_value;
            array['send_sms'] = data[ind].send_sms;
          }

          newArr.push(array);
           return newArr;
        });
};
});

and the corresponding function call:

var arr = $rootScope.getCommunication(2,3,$id)
                    .then(function(arr){console.log(arr)})

Answer 2

To ensure the proper execution of your code, it is important to return the promise instead of the array before it is updated. Asynchronous operations work by executing all synchronous code first before moving on to anything async.

var arr = []; // initialized first
promise.then(function(result){arr = result}) // executed third
return arr; // returned second

It is crucial to modify your code to return the promise. However, this also implies that your calling code must be able to handle asynchronous operations.

function asyncFunc() {
 return promise.then(function(result){return result});
}

asyncFunc().then(function(result) {console.log(result)}) // prints the value of result.

In relation to the provided code snippet above:

app.run(function($rootScope,Communications,$http,$filter) {

$rootScope.getCommunication = 
function(object_type,val,id,isType,isSendSms,getNotes){
  // retrieving data from a MySQL database
  return Communications.find({
        filter: {
          where: {
            and : [{
              communications_type_code : val
            },{
              object_id : id
            },{
              object_type : object_type
            }]
          }
        } 
      }).$promise
        .then(function(data) {
          var array = {};
          var newArray = [];
          for(var ind=0; ind<data.length; ind++){
            array['address_type'] = data[ind].address_type;
            array['contact_value'] = data[ind].contact_value;
            array['send_sms'] = data[ind].send_sms;
          }

          newArr.push(array);
           return newArr;
        });
};
});

and the corresponding function call:

var arr = $rootScope.getCommunication(2,3,$id)
                    .then(function(arr){console.log(arr)})

Answer 3

Answer №2

If you want to utilize callback functions, you can do so by following this method:

app.run(function($rootScope,Communications,$http,$filter) {

$rootScope.getCommunication = 
function(object_type,val,id,isType,isSendSms,getNotes, callback){

  var array = {};
  var newArr = [];

  // Fetching data from MySQL database
  var myVals = Communications.find({
        filter: {
          where: {
            and : [{
              communications_type_code : val
            },{
              object_id : id
            },{
              object_type : object_type
            }]
          }
        } 
      }).$promise
        .then(function(data) {

          for(var ind=0; ind<data.length; ind++){
            array['address_type'] = data[ind].address_type;
            array['contact_value'] = data[ind].contact_value;
            array['send_sms'] = data[ind].send_sms;
          }

          newArr.push(array);

           // Returning data using callback
           return callback(newArr);

        });

  // Returning data using callback
  return callback(newArr);

};
});

You can access the result by using the callback function like this:

$rootScope.getCommunication(2,3,$id, function(result){
  var arr = result
})

Answer 4

If you want to utilize callback functions, you can do so by following this method:

app.run(function($rootScope,Communications,$http,$filter) {

$rootScope.getCommunication = 
function(object_type,val,id,isType,isSendSms,getNotes, callback){

  var array = {};
  var newArr = [];

  // Fetching data from MySQL database
  var myVals = Communications.find({
        filter: {
          where: {
            and : [{
              communications_type_code : val
            },{
              object_id : id
            },{
              object_type : object_type
            }]
          }
        } 
      }).$promise
        .then(function(data) {

          for(var ind=0; ind<data.length; ind++){
            array['address_type'] = data[ind].address_type;
            array['contact_value'] = data[ind].contact_value;
            array['send_sms'] = data[ind].send_sms;
          }

          newArr.push(array);

           // Returning data using callback
           return callback(newArr);

        });

  // Returning data using callback
  return callback(newArr);

};
});

You can access the result by using the callback function like this:

$rootScope.getCommunication(2,3,$id, function(result){
  var arr = result
})

Obtaining information from AngularJS callback function in loopback: A comprehensive guide

Answer №1

Answer №2

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