| # Comments | |
| ## This store has the following structure | |
| ``` | |
| comments = { | |
| items: Immutable.Map<CommentTargetId, Immutable.List<Comment>>, // Comment is a Immutable.Map in the shape that returned by wpcom, ordered by date DESC | |
| requests: Immutable.Map<CommentTargetId, Map<RequestId, ActionType>>, | |
| totalCommentsCount: Immutable.Map<CommentTargetId, Number> | |
| }>; | |
| ``` | |
| ## Types | |
| ```text | |
| CommentTargetId: `${siteId}-${postId}`; | |
| RequestId: `${siteId}-${postId}-${stringify(query)}`; // query is the query to wpcom replies() | |
| ``` | |
| ## Selectors | |
| All selectors receive redux state and { siteId, postId }. | |
| The more "complex" ones, like `getPostCommentsTree` implemented with `lib/combine-selector`. | |
| getPostCommentsTree - returns a memoized comments tree of the form: | |
| ``` | |
| Tree: Map<CommentId, CommentNode>; | |
| in addition to the CommentId => CommentNode map, it has the following property: | |
| children: List<CommentId> // root-level comments ordered by date | |
| ``` | |
| ``` | |
| CommentNode: Map<> { | |
| children: List<CommentId>, | |
| data: Map | undefined, // the comment as received from wpcom API, if not yet received: undefined | |
| parentId: CommentId | null | undefined, // if we don't know yet, set to undefined. if comment has parent then set to number else to null | |
| } | |
| ``` | |
| ### Simple selectors | |
| getPostCommentItems - gets items of siteId, postId; | |
| getPostTotalCommentsCount - gets totalCommentsCount of siteId, postId | |
| ### Compute selectors | |
| getPostMostRecentCommentDate - gets the date of most recent comment | |
| getPostOldestCommentDate - gets the date of the earliest comment | |
| getPostCommentsTree - computes a comments tree | |
| haveMoreCommentsToFetch - concludes whether there are more comments to fetch according to totalCommentsCount and items.size | |
| ## How it works | |
| ### Comments fetching | |
| We pull from the API in reverse chronological order (going back in time with `before` field) via `actions#requestPostComments()`, | |
| building up the comment tree (`reducer#tree`) as we process each comment. | |
| Since replies have to happen after the initial comment, we'll process all replies to a comment before the comment itself, | |
| util we have seen an actual node, a placeholder CommentNode with `parentId === undefined` and `data === undefined` is | |
| placed on the tree. | |
| _Note: Since we haven't seen the parent of the placeholder CommentNode, that node won't be reachable from the root | |
| children list, but can be reached directly by ID._ | |