AngularJS drop down (ng- options) not binding - string to object (initial selection)

Question

I am having a problem binding data retrieved from the server to a drop down list. The main issue I think is the fact that the comparison is done on differing object types.

For example: 1. The object returned from the server contains a currency code string. we want this to be bound to an item in the dropdown list

"baseCurrencyCode":"GBP"

2. The view model returns the list of currencies.. These are returned as a list of currency objects with different properties

   {"currencies":[{"id":1,"rateId":0,"abbreviation":"AFN","description":"Afghani","rate":0.0,"rateDescription":null,"languageCode":"en-gb","isDefault":true,"fullDescription":"AFN - Afghani - ","shortDescription":"AFN - Afghani"}}
   

etc.

Currently, I have got this working by writing a function to go through every property for every item in the list, find the correct property we wish to compare to - do the comparison and then return the initial selection.

When calling my save method I then need to manually bind the currency abbreviation to the object I wish to return to the server.

Surely there must be a better way to do this?

Some of my code for reference..

<select ng-model="selectedCurrency" ng-options="currency.shortDescription for currency in viewModel.currencies"></select>

// Call to my custom method..List, PropertyName, value to compare 
$scope.selectedCurrency = InitialiseDropdown($scope.viewModel.currencies, "abbreviation", $scope.updatedObject.baseCurrencyCode);

// Code executed when saving - to bind the currency to the updated object
$scope.updatedObject.baseCurrencyCode = $scope.selectedCurrency.abbreviation;

Any help is appreciated!

EDIT Sorry if I wasn't clear enough.. To summarise..

The main problem here is binding to the drop down and initial selection.

The object we are updating contains a parameter (string) of the currency abbreviation.

The list we select from is a list of currency objects. As these are two differing object types I have been unable to plug in angulars 2 way binding and have written some code to do this on initial retrieval and when saving.

The cleanest way to fix this would be to return a currency object in our retrieval instead of a simple string of the abbreviation, but this is not an option.

Is there a better way of enabling 2 way binding on different object types ?

Thanks again

Answer 1

It is not exactly clear what the problem is, but you can save yourself some work by binding the <select> to the currently selected currency object (so you don't have to look it up later).
select + ngOptions allow you to bind to one value while displaying another, with the following syntax:

<select ng-model="selectedCurrency"
        ng-options="currency as currency.shortDescription
                    for currency in viewModel.currencies">
</select>

In the above example, $scope.selectedCurrency will be bound to the whole currency object, but currency.shortDescription will be displayed in the dropdown.

---

See, also, this short demo.

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UPDATE:

In case you don't need to bind to the whole currency object, but just bind updatedObject's baseCurrencyCode property to the abbreviation of the selected (in dropdown) currency, you can do it like this:

<!-- In the VIEW -->
<select ng-model="updatedObject.baseCurrencyCode"
        ng-options="c.abbreviation as c.shortDescription
                    for c in currencies">
</select>

// In the CONTROLLER
$scope.currencies = [...];
$scope.updatedObject = {
    ...
    baseCurrencyCode: <baseCurrencyCodeFromServer>
};

---

See, also, that short demo.