Add Post class, as children of Topic.

UnitTestProject1/Tests/FlowTests.cs

@@ -24,8 +24,11 @@ public async Task BoardTest()
             var board = new Board(await WpBetaSiteAsync, "Talk:Flow QA");
             await board.RefreshAsync();
             ShallowTrace(board);
+            var x = await board.EnumTopicsAsync(20).Take(10).ToArray();
+            var y = await board.EnumTopicsAsync(10).ToArray();
             var topics = await board.EnumTopicsAsync(10).Take(10).ToArray();
-            ShallowTrace(topics);
+            ShallowTrace(topics, 3);
+            Assert.DoesNotContain(null, topics);
         }
 
     }

WikiClientLibrary/Flow/Board.cs

@@ -51,7 +51,7 @@ public Board(WikiSite site, string title)
 
         /// <summary>Latest header content revision.</summary>
         public Revision HeaderRevision { get; private set; }
-        
+
         /// <inheritdoc cref="RefreshAsync(CancellationToken)"/>
         public Task RefreshAsync()
         {
@@ -104,11 +104,14 @@ public IAsyncEnumerable<Topic> EnumTopicsAsync(int pageSize)
             {
                 if (eof) return null;
                 var jresult = await Site.GetJsonAsync(new WikiFormRequestMessage(queryParams), ct);
-                var jtopiclist = (JObject) jresult["flow"]["view-topiclist"]["result"]["topiclist"];
-                var topics = Topic.FromJsonTopicList(Site, jtopiclist);
+                var jtopiclist = (JObject)jresult["flow"]["view-topiclist"]["result"]["topiclist"];
+                // ISSUE directly return SelectArrayIterator<TSource, TResult> via Enumerable.Select
+                // can cause strange behavior when chained with other async LINQ methods. See
+                // https://github.com/CXuesong/WikiClientLibrary/issues/27
+                var topics = Topic.FromJsonTopicList(Site, jtopiclist).ToList();
                 // TODO Implement Pagination
                 eof = true;
-                return Tuple.Create(topics, eof);
+                return Tuple.Create((IEnumerable<Topic>)topics, true);
             });
             return ienu.SelectMany(t => t.ToAsyncEnumerable());
         }

WikiClientLibrary/Flow/Post.cs

@@ -0,0 +1,89 @@
+using System;
+using System.Collections.Generic;
+using System.Collections.ObjectModel;
+using System.Diagnostics;
+using System.Linq;
+using System.Text;
+using Newtonsoft.Json.Linq;
+using WikiClientLibrary.Sites;
+
+namespace WikiClientLibrary.Flow
+{
+    /// <summary>
+    /// Represents a normal flow post.
+    /// </summary>
+    public sealed class Post
+    {
+
+        internal static readonly IList<Post> EmptyPosts = new Post[] { };
+
+        /// <summary>
+        /// Initializes a new <see cref="Post"/> instance from MW site and post workflow ID.
+        /// </summary>
+        /// <param name="site">MediaWiki site.</param>
+        /// <param name="workflowId">Full page title of the Flow discussion board, including <c>Topic:</c> namespace prefix.</param>
+        public Post(WikiSite site, string workflowId)
+        {
+            Site = site ?? throw new ArgumentNullException(nameof(site));
+            WorkflowId = workflowId ?? throw new ArgumentNullException(nameof(workflowId));
+        }
+
+        /// <summary>
+        /// The MediaWiki site hosting this post.
+        /// </summary>
+        public WikiSite Site { get; }
+
+        /// <summary>
+        /// Workflow ID of the post.
+        /// </summary>
+        public string WorkflowId { get; private set; }
+
+        /// <summary>
+        /// Gets the last revision of the post.
+        /// </summary>
+        public Revision LastRevision { get; private set; }
+
+        /// <summary>
+        /// Gets a read-only view of the replies.
+        /// </summary>
+        public IList<Post> Replies { get; private set; } = EmptyPosts;
+
+        internal static Post FromJson(WikiSite site, JObject topicList, string workflowId)
+        {
+            var post = new Post(site, workflowId);
+            post.LoadFromJsonTopicList(topicList, workflowId);
+            return post;
+        }
+
+        // topicList: The topiclist node of a view-topiclist query result.
+        internal void LoadFromJsonTopicList(JObject topicList, string workflowId)
+        {
+            var revisionId = (string)topicList["posts"][workflowId]?.First;
+            if (revisionId == null)
+                throw new ArgumentException("Cannot find workflow ID " + workflowId + " in [posts] array.", nameof(workflowId));
+            var jrevision = (JObject)topicList["revisions"][revisionId];
+            if (jrevision == null)
+                throw new UnexpectedDataException("Cannot find revision " + revisionId + " in [revisions] array.");
+            var rev = jrevision.ToObject<Revision>(FlowUtility.FlowJsonSerializer);
+            if (rev.ReplyIds == null || rev.ReplyIds.Count == 0)
+            {
+                Replies = EmptyPosts;
+            }
+            else
+            {
+                var posts = new List<Post>(rev.ReplyIds.Count);
+                posts.AddRange(rev.ReplyIds.Select(pid => FromJson(Site, topicList, pid)));
+                Replies = new ReadOnlyCollection<Post>(posts);
+            }
+            WorkflowId = workflowId;
+        }
+
+        /// <inheritdoc />
+        public override string ToString()
+        {
+            var result = "[" + WorkflowId + "]";
+            if (Replies.Count > 0) result += "[Re:" + Replies.Count + "]";
+            return result;
+        }
+    }
+}

WikiClientLibrary/Flow/Revision.cs

@@ -72,8 +72,9 @@ private string RawChangeType
         //[JsonProperty]
         //public DateFormats DateFormats { get; private set; }
 
+        // Can be JObject, or empty JArray
         [JsonProperty]
-        public JObject Properties { get; private set; }
+        public JToken Properties { get; private set; }
 
         [JsonProperty]
         public bool IsOriginalContent { get; private set; }
@@ -102,8 +103,8 @@ private string RawChangeType
         /// <summary>
         /// Workflow ID of the replies.
         /// </summary>
-        [JsonProperty]
-        public IList<string> Replies { get; private set; }
+        [JsonProperty("replies")]
+        public IList<string> ReplyIds { get; private set; }
 
         /// <summary>
         /// HTML links to show different views.

WikiClientLibrary/Flow/Topic.cs

@@ -21,27 +21,24 @@ public class Topic : IWikiClientLoggable
     {
         private ILoggerFactory _LoggerFactory;
         private ILogger logger = NullLogger.Instance;
-        private readonly List<Revision> _Posts = new List<Revision>();
 
         /// <summary>
-        /// Initializes a new <see cref="Board"/> instance from MW site and board page title.
+        /// Initializes a new <see cref="Topic"/> instance from MW site and topic page title.
         /// </summary>
         /// <param name="site">MediaWiki site.</param>
-        /// <param name="title">Full page title of the Flow discussion board, including namespace prefix.</param>
+        /// <param name="title">Full page title of the Flow discussion board, including <c>Topic:</c> namespace prefix.</param>
         public Topic(WikiSite site, string title)
         {
             Site = site ?? throw new ArgumentNullException(nameof(site));
             Title = title ?? throw new ArgumentNullException(nameof(title));
             LoggerFactory = site.LoggerFactory;
-            Posts = new ReadOnlyCollection<Revision>(_Posts);
         }
 
-        internal Topic(WikiSite site)
+        private Topic(WikiSite site)
         {
             Debug.Assert(site != null);
             Site = site;
             LoggerFactory = site.LoggerFactory;
-            Posts = new ReadOnlyCollection<Revision>(_Posts);
         }
 
         /// <summary>
@@ -74,10 +71,8 @@ internal static IEnumerable<Topic> FromJsonTopicList(WikiSite site, JObject topi
         // topicList: The topiclist node of a view-topiclist query result.
         internal void LoadFromJsonTopicList(JObject topicList, string workflowId)
         {
-            _Posts.Clear();
             TopicTitleRevision = null;
             WorkflowId = null;
-            if (_Posts.Capacity < topicList.Count) _Posts.Capacity = topicList.Count;
             var revisionId = (string)topicList["posts"][workflowId]?.First;
             if (revisionId == null)
                 throw new ArgumentException("Cannot find workflow ID " + workflowId + " in [posts] array.", nameof(workflowId));
@@ -89,14 +84,20 @@ internal void LoadFromJsonTopicList(JObject topicList, string workflowId)
             TopicTitleRevision = rev;
             Title = TopicTitleRevision.ArticleTitle;
             WorkflowId = TopicTitleRevision.WorkflowId;
-            // TODO Parse the replies.
-            foreach (var replyIds in rev.Replies)
+            if (rev.ReplyIds == null || rev.ReplyIds.Count == 0)
             {
-
+                Posts = Post.EmptyPosts;
             }
+            else
+            {
+                var posts = new List<Post>(rev.ReplyIds.Count);
+                posts.AddRange(rev.ReplyIds.Select(pid => Post.FromJson(Site, topicList, pid)));
+                Posts = new ReadOnlyCollection<Post>(posts);
+            }
+            WorkflowId = workflowId;
         }
 
-        public IList<Revision> Posts { get; }
+        public IList<Post> Posts { get; private set; }
 
         /// <summary>
         /// Workflow ID of the topic.