Integrating HERE Maps with Flutter Typeahead package for search suggestions

Question

I am using flutter_typeahead for showing place suggestions to users as they search using a text field and fetching these suggestions from HERE Maps. flutter typeahead package has an asynchronous callback function that requires, a list of strings to be returned that would then be shown to the user. The problem is that HERE Map's search engine doesn't return the search results and instead takes its own callback function which is called with the suggestions. Here's an example of it to make it clear.

TypeAheadFormField(
  suggestionsCallback: (pattern) async {
    final taskHandle = _searchEngine.suggest(
        TextQuery.withAreaCenter(pattern, centerCoords),
        searchOptions,
        (error, suggestions) {
          // How can i return these suggestions back from the suggestionsCallback?
          final suggestionStrings = _handleSuggestions(error, suggestions);
        },
    );
  },
),

The taskHandle also doesn't provide any way to await the searchEngine so I basically have no way of knowing when the suggestions will be available to return them by using a global variable (storing the suggestions after the searchEngine completes its callback and then returning the stored suggestions from the suggestionCallback.

Answer 1

The HERE SDK notifies in the SuggestionCallback when suggestions are available. Inside the callback you can proceed with your app logic, and, e.g. call typeAhead:

_searchEngine.suggest(
    TextQuery.withAreaCenter(
        "piz", // User typed "piz".
        centerGeoCoordinates),
    searchOptions, (SearchError? searchError, List<Suggestion>? list) async {
  // Suggestions have been provided by HERE SDK. Use the results ...
});

Instead of using global variables it's probably better to proceed inside the callback. However, if you want to make this call blocking, you can wrap it in an async method that returns a Future. When calling this method you can await the resuts.