Exploring the world of data manipulation in AngularJS

Seeking to comprehend the rationale behind it, I will share some general code snippets:

1) Fetching data from a JSON file using the "loadData" service:

return {
        myData: function(){
           return $http.get(path + "data.json");
        }
}

2) Within the main controller:

loadData.myData().then(function(result){
      $scope.vm.myData = result.data;
});

Then, whenever I try to access it with:

console.log($scope.vm)

I can see the entire object containing the data, but if I try:

console.log($scope.vm.myData)

It always returns as "undefined", and cannot be utilized in any function (except by accessing it within the above-mentioned function). My goal is to fetch some data initially and then make it accessible wherever needed.

Answer №1

If the code structure resembles what you see here, the second console statement gets executed before the asynchronous call completes (i.e. before the promise is resolved).

fetchData.myData()
   .then(function(result) {
      $scope.data = result.data;
      console.log(1, $scope);  // Executes when the promise is resolved
   });
console.log(2, $scope);  // Executed immediately after data request (no guarantee of resolved promise).

Therefore, any operations requiring the returned data must be placed inside the then function to ensure access to the data.

The output depicted above would show:

2 undefined
1 [your data object]

For more insights on promises and asynchronous calls within Angular, check out this incredible resource with cartoons!

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