Try to use cache.

Author: guojiex

lib/CustomWebSearchPage.dart

@@ -51,7 +51,7 @@ class _CustomWebSearchDemoState extends State<CustomWebSearchDemo> {
         ),
         actions: <Widget>[
           new IconButton(
-            tooltip: 'Image Search',
+            tooltip: 'Search',
             icon: const Icon(Icons.search),
             onPressed: triggerShowSearch,
           ),

lib/search_data_source.dart

@@ -8,6 +8,7 @@ import 'package:flutter/services.dart' show rootBundle;
 import "package:googleapis_auth/auth_io.dart" as auth;
 import 'package:googleapis/customsearch/v1.dart' as customsearch;
 import 'package:english_words/english_words.dart';
+import 'package:async/async.dart';
 
 /// A wrapper class for [customsearch.Result].
 /// [SearchResult] will use the landing page link to measure if two results are
@@ -50,9 +51,6 @@ class SearchResult {
           : result.image.contextLink.hashCode;
 }
 
-/// A wrapper class to generate search request. To make caching possible.
-class SearchRequest {}
-
 class Promotion {
   final customsearch.Promotion promotion;
 
@@ -76,8 +74,8 @@ class SearchResults {
 
   SearchResults(customsearch.Search search) {
     var results = new List<SearchResult>();
-    search.items.forEach((item) =>
-        results.add(SearchResult.escapeLineBreakInSnippet(item)));
+    search.items.forEach(
+            (item) => results.add(SearchResult.escapeLineBreakInSnippet(item)));
     // Deduplicate search result.
     this.searchResults = Set<SearchResult>.from(results).toList();
   }
@@ -107,6 +105,9 @@ class FakeSearchDataSource implements SearchDataSource {
     'promotion': _StaticSearchResponse(
         assetPath: 'res/sampledata/nytimes_with_promotion.json'),
   };
+  final ExpireCache<SearchQuery, SearchResults> _cache =
+  ExpireCache<SearchQuery, SearchResults>();
+  final String cx = 'fake_cx';
 
   FakeSearchDataSource() {
     searchResponses.keys.forEach((key) {
@@ -119,6 +120,8 @@ class FakeSearchDataSource implements SearchDataSource {
     await rootBundle.loadString(assetPath);
   }
 
+  int count = 0;
+
   @override
   Future<SearchResults> search(String query, {String searchType}) async {
     if (!searchResponses.containsKey(query)) {
@@ -127,18 +130,186 @@ class FakeSearchDataSource implements SearchDataSource {
     if (searchResponses[query].searchType != searchType) {
       return SearchResults.empty();
     }
+    SearchQuery searchQuery =
+    SearchQuery(query, this.cx, searchType: searchType);
+    var cachedResponse = await _cache.get(searchQuery);
+    if (cachedResponse != null) {
+      return cachedResponse;
+    }
     Map searchMap = jsonDecode(searchResponses[query].searchResponseJsonString);
     customsearch.Search search = customsearch.Search.fromJson(searchMap);
-    return SearchResults(search);
+
+    print('count: $count');
+    count++;
+
+    var result = SearchResults(search);
+    await _cache.set(searchQuery, result);
+    return result;
   }
 }
 
+/// A wrapper class for search request, to make caching search request possible.
+class SearchQuery {
+  String q;
+  String c2coff;
+  String cr;
+  String cx;
+  String dateRestrict;
+  String exactTerms;
+  String excludeTerms;
+  String fileType;
+  String filter;
+  String gl;
+  String googlehost;
+  String highRange;
+  String hl;
+  String hq;
+  String imgColorType;
+  String imgDominantColor;
+  String imgSize;
+  String imgType;
+  String linkSite;
+  String lowRange;
+  String lr;
+  int num;
+  String orTerms;
+  String relatedSite;
+  String rights;
+  String safe;
+  String searchType;
+  String siteSearch;
+  String siteSearchFilter;
+  String sort;
+  int start;
+
+  /// Used to get partial response, see:
+  /// https://developers.google.com/custom-search/v1/performance#partial
+  String fields;
+
+  SearchQuery(this.q, this.cx,
+      {this.c2coff,
+        this.cr,
+        this.dateRestrict,
+        this.exactTerms,
+        this.excludeTerms,
+        this.fileType,
+        this.filter,
+        this.gl,
+        this.googlehost,
+        this.highRange,
+        this.hl,
+        this.hq,
+        this.imgColorType,
+        this.imgDominantColor,
+        this.imgSize,
+        this.imgType,
+        this.linkSite,
+        this.lowRange,
+        this.lr,
+        this.num,
+        this.orTerms,
+        this.relatedSite,
+        this.rights,
+        this.safe,
+        this.searchType,
+        this.siteSearch,
+        this.siteSearchFilter,
+        this.sort,
+        this.start,
+        this.fields});
+
+  Future<SearchResults> runSearch(customsearch.CustomsearchApi api) async {
+    return SearchResults(
+        await api.cse.list(q, cx: cx, searchType: this.searchType));
+  }
+
+  @override
+  String toString() {
+    return 'SearchQuery{q: $q, c2coff: $c2coff, cr: $cr, cx: $cx, dateRestrict: $dateRestrict, exactTerms: $exactTerms, excludeTerms: $excludeTerms, fileType: $fileType, filter: $filter, gl: $gl, googlehost: $googlehost, highRange: $highRange, hl: $hl, hq: $hq, imgColorType: $imgColorType, imgDominantColor: $imgDominantColor, imgSize: $imgSize, imgType: $imgType, linkSite: $linkSite, lowRange: $lowRange, lr: $lr, num: $num, orTerms: $orTerms, relatedSite: $relatedSite, rights: $rights, safe: $safe, searchType: $searchType, siteSearch: $siteSearch, siteSearchFilter: $siteSearchFilter, sort: $sort, start: $start, fields: $fields}';
+  }
+
+  @override
+  bool operator ==(Object other) =>
+      identical(this, other) ||
+          other is SearchQuery &&
+              runtimeType == other.runtimeType &&
+              q == other.q &&
+              c2coff == other.c2coff &&
+              cr == other.cr &&
+              cx == other.cx &&
+              dateRestrict == other.dateRestrict &&
+              exactTerms == other.exactTerms &&
+              excludeTerms == other.excludeTerms &&
+              fileType == other.fileType &&
+              filter == other.filter &&
+              gl == other.gl &&
+              googlehost == other.googlehost &&
+              highRange == other.highRange &&
+              hl == other.hl &&
+              hq == other.hq &&
+              imgColorType == other.imgColorType &&
+              imgDominantColor == other.imgDominantColor &&
+              imgSize == other.imgSize &&
+              imgType == other.imgType &&
+              linkSite == other.linkSite &&
+              lowRange == other.lowRange &&
+              lr == other.lr &&
+              num == other.num &&
+              orTerms == other.orTerms &&
+              relatedSite == other.relatedSite &&
+              rights == other.rights &&
+              safe == other.safe &&
+              searchType == other.searchType &&
+              siteSearch == other.siteSearch &&
+              siteSearchFilter == other.siteSearchFilter &&
+              sort == other.sort &&
+              start == other.start &&
+              fields == other.fields;
+
+  @override
+  int get hashCode =>
+      q.hashCode ^
+      c2coff.hashCode ^
+      cr.hashCode ^
+      cx.hashCode ^
+      dateRestrict.hashCode ^
+      exactTerms.hashCode ^
+      excludeTerms.hashCode ^
+      fileType.hashCode ^
+      filter.hashCode ^
+      gl.hashCode ^
+      googlehost.hashCode ^
+      highRange.hashCode ^
+      hl.hashCode ^
+      hq.hashCode ^
+      imgColorType.hashCode ^
+      imgDominantColor.hashCode ^
+      imgSize.hashCode ^
+      imgType.hashCode ^
+      linkSite.hashCode ^
+      lowRange.hashCode ^
+      lr.hashCode ^
+      num.hashCode ^
+      orTerms.hashCode ^
+      relatedSite.hashCode ^
+      rights.hashCode ^
+      safe.hashCode ^
+      searchType.hashCode ^
+      siteSearch.hashCode ^
+      siteSearchFilter.hashCode ^
+      sort.hashCode ^
+      start.hashCode ^
+      fields.hashCode;
+}
+
 /// The search data source that uses Custom Search API.
 class CustomSearchDataSource implements SearchDataSource {
   final String cx;
   final String apiKey;
-  var api;
+  customsearch.CustomsearchApi api;
   int searchCount = 0;
+  final ExpireCache<SearchQuery, SearchResults> _cache =
+  ExpireCache<SearchQuery, SearchResults>();
 
   CustomSearchDataSource({@required this.cx, @required this.apiKey}) {
     var client = auth.clientViaApiKey(apiKey);
@@ -150,9 +321,20 @@ class CustomSearchDataSource implements SearchDataSource {
     if (query.isEmpty) {
       return SearchResults.empty();
     }
-    customsearch.Search search =
-    await this.api.cse.list(query, cx: this.cx, searchType: searchType);
-    return SearchResults(search);
+    SearchQuery searchQuery =
+    SearchQuery(query, this.cx, searchType: searchType);
+
+    final cachedResponse = await _cache.get(searchQuery);
+    if (cachedResponse != null) {
+      return cachedResponse;
+    }
+
+    print('count: $searchCount');
+    searchCount++;
+
+    final result = await searchQuery.runSearch(this.api);
+    await _cache.set(searchQuery, result);
+    return result;
   }
 }
 
@@ -162,6 +344,8 @@ abstract class AutoCompleteDataSource {
 
 class CommonEnglishWordAutoCompleteDataSource
     implements AutoCompleteDataSource {
+  const CommonEnglishWordAutoCompleteDataSource();
+
   @override
   List<String> getAutoCompletions({String query, int resultNumber = 10}) {
     var results = all.where((String word) => word.startsWith(query)).toList();

lib/search_result_page.dart

@@ -8,28 +8,33 @@ import 'shared_constant.dart';
 
 class CustomSearchSearchDelegate extends SearchDelegate<SearchResult> {
   SearchDataSource dataSource;
-  AutoCompleteDataSource autoCompleteDataSource =
-  CommonEnglishWordAutoCompleteDataSource();
+  AutoCompleteDataSource autoCompleteDataSource;
   SearchType searchType;
 
   CustomSearchSearchDelegate(
       {this.dataSource,
-      this.autoCompleteDataSource,
+        this.autoCompleteDataSource =
+        const CommonEnglishWordAutoCompleteDataSource(),
       this.searchType = SearchType.web});
 
   CustomSearchSearchDelegate.imageSearch(
       {this.dataSource,
-        this.autoCompleteDataSource,
+        this.autoCompleteDataSource =
+        const CommonEnglishWordAutoCompleteDataSource(),
         this.searchType = SearchType.image});
 
   CustomSearchSearchDelegate.fakeStaticSource() {
     this.dataSource = FakeSearchDataSource();
     this.searchType = SearchType.web;
+    this.autoCompleteDataSource =
+    const CommonEnglishWordAutoCompleteDataSource();
   }
 
   CustomSearchSearchDelegate.fakeStaticSourceImageSearch() {
     this.dataSource = FakeSearchDataSource();
     this.searchType = SearchType.image;
+    this.autoCompleteDataSource =
+    const CommonEnglishWordAutoCompleteDataSource();
   }
 
   @override
@@ -74,6 +79,7 @@ class CustomSearchSearchDelegate extends SearchDelegate<SearchResult> {
               tooltip: 'Clear',
               icon: const Icon(Icons.clear),
               onPressed: () async {
+                close(context, null);
                 await showSearch<SearchResult>(
                   context: context,
                   delegate: this,

pubspec.yaml

@@ -27,7 +27,7 @@ dependencies:
   googleapis_auth: ^0.2.6
   english_words: ^3.1.5
   url_launcher: ^4.0.3
-  expire_cache: ^1.0.3
+  expire_cache: ^1.0.4
 
 dev_dependencies:
   test: ^1.5.1+1