#118 Hack into continue param to avoid returning more than 1 imageinfo entry to the caller.

Author: CXuesong

UnitTestProject1/Tests/ValidationTests.cs

@@ -101,7 +101,7 @@ public async Task Issue118()
         // Just in case RefreshAsync gets into an infinite loop.
         using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(10));
 
-        await Assert.ThrowsAsync<UnexpectedContinuationLoopException>(() => page.RefreshAsync(new WikiPageQueryProvider
+        await page.RefreshAsync(new WikiPageQueryProvider
         {
             Properties =
             {
@@ -111,7 +111,11 @@ await Assert.ThrowsAsync<UnexpectedContinuationLoopException>(() => page.Refresh
                 new PageInfoPropertyProvider(),
                 new PagePropertiesPropertyProvider(),
             },
-        }, cts.Token));
+        }, cts.Token);
+
+        ShallowTrace(page.LastFileRevision);
+        Assert.NotNull(page.LastFileRevision);
+        Assert.Equal("image/jpeg", page.LastFileRevision!.Mime, StringComparer.OrdinalIgnoreCase);
     }
 
 }

WikiClientLibrary/Pages/Queries/Properties/FileInfoPropertyProvider.cs

@@ -28,6 +28,7 @@ public class FileInfoPropertyProvider : WikiPagePropertyProvider<FileInfoPropert
             "url",
             "size",
             "sha1",
+            "mime",
         };
         if (QueryExtMetadata)
             properties.Add("extmetadata");

WikiClientLibrary/RequestHelper.cs

@@ -97,7 +97,7 @@ public static int ParseContinuationParameters(JsonNode jresult, IDictionary<stri
         return null;
     }
 
-#region Page/Revision query
+    #region Page/Revision query
 
     public static async IAsyncEnumerable<JsonObject> QueryWithContinuation(WikiSite site,
         IEnumerable<KeyValuePair<string, object?>> parameters,
@@ -178,6 +178,13 @@ public static async Task RefreshPagesAsync(IEnumerable<WikiPage> pages, IWikiPag
             var site = sitePages.Key.Site;
             var queryParams = options.EnumParameters(site.SiteInfo.Version).ToDictionary();
             var titleLimit = options.GetMaxPaginationSize(site.SiteInfo.Version, site.AccountInfo.HasRight(UserRights.ApiHighLimits));
+            // Workaround https://github.com/CXuesong/WikiClientLibrary/issues/118
+            // Currently, `prop=revisions` itself does not trigger continuation unless `rvlimit` has been specified. Good.
+            // However, `prop=imageinfo` insists it return all the items eventually
+            // meaning it will trigger continuation even if WCL consumer is only refreshing 1 page and
+            // might only be interested in the latest n versions.
+            var needPropImageInfoContinueHack = queryParams.GetValueOrDefault("prop")?.ToString()
+                ?.Contains("imageinfo", StringComparison.Ordinal) ?? false;
             using (site.BeginActionScope(sitePages, options))
             {
                 foreach (var partition in sitePages.Partition(titleLimit))
@@ -208,6 +215,20 @@ public static async Task RefreshPagesAsync(IEnumerable<WikiPage> pages, IWikiPag
                         ParseContinuationParameters(jobj1, queryParams1, continuationParams);
                         while (continuationStatus != CONTINUATION_DONE)
                         {
+                            if (needPropImageInfoContinueHack
+                                && partition.Count == 1
+                                && continuationParams.ContainsKey("iistart"))
+                            {
+                                var continueValue = continuationParams.GetValueOrDefault("continue");
+                                if (continueValue != null && !continueValue.Contains("imageinfo", StringComparison.Ordinal))
+                                {
+                                    // Workaround https://github.com/CXuesong/WikiClientLibrary/issues/118
+                                    // Fiddle with `continue` so it won't return old file revisions.
+                                    continuationParams["continue"] = string.IsNullOrEmpty(continueValue)
+                                        ? "||imageinfo"
+                                        : continueValue + "|imageinfo";
+                                }
+                            }
                             if (continuationStatus == CONTINUATION_LOOP)
                                 throw new UnexpectedContinuationLoopException();
                             Debug.Assert(continuationStatus == CONTINUATION_AVAILABLE);
@@ -323,7 +344,7 @@ public static async Task RefreshPagesAsync(IEnumerable<WikiPage> pages, IWikiPag
         }
     }
 
-#endregion
+    #endregion
 
     /// <summary>
     /// Asynchronously purges the pages.
@@ -408,7 +429,10 @@ public static async Task PatrolAsync(WikiSite site, long? recentChangeId, long?
         {
             var jresult = await site.InvokeMediaWikiApiAsync(new MediaWikiFormRequestMessage(new
             {
-                action = "patrol", rcid = recentChangeId, revid = revisionId, token = WikiSiteToken.Patrol,
+                action = "patrol",
+                rcid = recentChangeId,
+                revid = revisionId,
+                token = WikiSiteToken.Patrol,
             }), cancellationToken);
             if (recentChangeId != null) Debug.Assert((int)jresult["patrol"]["rcid"] == recentChangeId.Value);
         }