Search Delegate Custom

search_delegate_custom.dart

import 'package:flutter/material.dart';

///This class customize the default class SearchDelegate to use less code in each implementation
///
///The `Custom` sufix refers to properties from this class
///
///`Constructor class`
///
/// ```dart
///SearchDelegateCustom(
///       {@required this.listOfData,
///      this.searchFieldLabel = 'Búscar',
///      this.buildActionsCustom,
///      this.buildLeadingCustom})
/// ```
///
abstract class SearchDelegateCustom<T> extends SearchDelegate<T> {
  final String searchFieldLabel;
  final List<Widget> buildActionsCustom;
  final Widget buildLeadingCustom;

  ///The data to search
  final List<T> listOfData;

  SearchDelegateCustom(
      {@required this.listOfData,
      this.searchFieldLabel = 'Búscar',
      this.buildActionsCustom,
      this.buildLeadingCustom})
      : assert(listOfData != null),
        super(
            searchFieldLabel: searchFieldLabel,
            keyboardType: TextInputType.text);

  ///`Description:` Suggestions shown in the body of the search page while the user types a
  /// query into the search field.
  ///
  ///
  ///Tipically this method should return a [ListView] with a [ListTile]
  ///
  ///
  ///When [onTap] is called [query] should be `updated with` the
  ///corresponding `suggestion` and the results page should be shown
  /// by calling [showResults].
  ///
  ///* Copied from SearchDelegate docs
  ///
  ///This can be done. But if you rather make your own flow. You can use [close]
  ///method to return the value selected by the user
  ///
  ///`NOTE:`Suggestions and Results methods have similar behaviors. The same method can be used in both methods
  Widget buildSuggestionsCustom(BuildContext context, List<T> listOfData);

  ///`Description:` The results shown after the user submits a search from the search page.
  ///
  ///Tipically this method should return a [ListView] with a [ListTile]
  ///
  //////When [onTap] is called [close] should be called
  /// with the selected result as argument.
  ///`NOTE:`Results and Suggestions methods have similar behaviors. The same method can be used in both methods
  Widget buildResultsCustom(BuildContext context, List<T> listOfData);

  @override
  List<Widget> buildActions(BuildContext context) =>
      buildActionsCustom ??
      [
        query.isNotEmpty
            ? IconButton(
                icon: Icon(Icons.clear),
                onPressed: () => query = '',
              )
            : Container(),
      ];

  @override
  Widget buildLeading(BuildContext context) =>
      buildLeadingCustom ??
      IconButton(
        icon: Icon(Icons.arrow_back),
        onPressed: () => close(context, null),
      );

  @override
  Widget buildResults(BuildContext context) =>
      buildResultsCustom(context, listOfData);

  @override
  Widget buildSuggestions(BuildContext context) =>
      buildSuggestionsCustom(context, listOfData);
}

//The code from above is enough to implement something good
//But if you want to use just the listOfData, buildResults and buildSuggestions params
//You can use the next solution or create your own one

 ///This class is used to create instances of SearchDelegate and reuse code
class _SearchDelegateUseCase<T> extends SearchDelegateCustom {
  ///These functions allow to display the data in the UI
  BuildDelegateResultSuggestion buildResult, buildSuggestion;
  List<T> listOfData;

  _SearchDelegateUseCase(
      this.buildResult, this.buildSuggestion, this.listOfData)
      : assert(buildResult != null),
        assert(buildSuggestion != null),
        assert(listOfData != null),
        super(
          listOfData: listOfData,
        );

  @override
  Widget buildResultsCustom(BuildContext context, List list) =>
      buildResult(context, list);

  @override
  Widget buildSuggestionsCustom(BuildContext context, List list) =>
      buildSuggestion(context, list);
}

///Allow to build the result o suggestion part
typedef Widget BuildDelegateResultSuggestion<T>(
    BuildContext context, List<T> listOfData);

///Get the function that allow to call the SearchDelegate
///
///Also this allows reuse the code
mixin SearchMixin {
  ///Call this function to create a delegate customizer for the search
  _SearchDelegateUseCase getDelegate<T>({
    @required List<T> listOfData,
    @required BuildDelegateResultSuggestion<T> result,
    @required BuildDelegateResultSuggestion<T> suggestion,
  }) {
    return _SearchDelegateUseCase(result, suggestion, listOfData);
  }
}

//Or you can use Provider to listen to the changes instead of listOfData
//You can access through the context