Table of Contents

Viewing threads

Warning

Treat data received from Bluesky, AT Protocol services, and streams such as Jetstream and the firehose as untrusted. This includes post and message text, profile and list metadata, labels, error details such as AtErrorDetail, and raw JSON. Before displaying it, encode it for the output context (for example, HTML-encode it for a web page). Before using a URL in a link or other active context, check its scheme against an allow-list of the schemes your application expects, such as https; a well-formed URL can still use an active scheme such as javascript:, which can lead to cross-site scripting. Validate other values before using them in active contexts.

The sample code on this page is for illustration. It does not sanitize or otherwise validate the input it uses; apply the validation and encoding appropriate for your application.

A thread refers to a post, its replies (descendants), and its parents (ancestors). Fetching a thread is done with agent.GetPostThread() , which accepts the following key parameters:

GetPostThread(uri, depth?, parentHeight?)

Parameter Type Description Required Default Minimum Maximum
uri AtUri The at:// uri of the post you'd like to fetch. Yes
depth int The depth of the descendant post tree you'd like to fetch. No 6 0 1000
parentHeight int The height of the ancestor post tree you'd like to fetch. No 80 0 1000 
var getPostThreadResult = await agent.GetPostThread(
                    uri: "at://did:plc:oio4hkxaop4ao4wz2pp3f4cr/app.bsky.feed.post/3lnoktfc7l22i");

Result shape

The result of a GetPostThread() is a PostThread which contains the Thread and any ThreadGate rules applied to it.

Thread has a Post property, this is the root post, the one whose at:// uri you provided, a Parent property, which is a nested tree of ancestors (if any), and Replies, a one dimensional array of replies (if any).

As Replies is one-dimensional, to facilitate the construction of a tree from this data, each reply in the array contains references to its immediate parent (ancestor) and immediate child (descendant).

Post, Parent and each entry in Replies can either be a ThreadViewPost, a NotFoundPost or a BlockedPost type.

The depth and parentHeight parameters

depth and parentHeight can be thought of as the distance from the root post to its most distant child or parent.

root
├── child 1
│   ├── child 1.1
│   │   └── child 1.1.1
│   └── child 1.2
└── child 2
    └── child 2.1
        └── child 2.1.1

Above, if you were to fetch the root post, child 1.2 is at a depth of 2 from the root, its ancestor. If you were to fetch child 2.1.1 directly, root would be at a height of 3 from child 2.1.1, its descendant.

Handling blocks, takedowns, and not found

As you can see in the types above, the root post, parent or reply in the response can be either a ThreadViewPost, a NotFoundPost, or a BlockedPost.

A NotFoundPost is returned when the post either does not exist, has been deleted by its author, or has been taken down by a moderation service.

A BlockedPost is returned when either the post author has blocked the viewer, or the viewer has blocked the author.

You can use C# pattern matching to perform different actions depending on the type of the Post, its Parent or any of its Replies.

var getPostThreadResult = await agent.GetPostThread(
    uri: "at://did:plc:ec72yg6n2sydzjvtovvdlxrk/app.bsky.feed.post/3lnorz7eorc2z", cancellationToken: cancellationToken);

if (getPostThreadResult.Succeeded)
{
    switch (getPostThreadResult.Result.Thread)
    {
        case ThreadViewPost threadViewPost:
            // The post exists so you can act on it.
            Console.WriteLine(threadViewPost.Post.Record.Text);
            break;

        case NotFoundPost notFoundPost:
            // The post never existed, was deleted, or taken down.
            Console.WriteLine($"Post at {notFoundPost.Uri} is unavailable");
            break;

        case BlockedPost blockedPost:
            // The post author blocked the viewer,
            // or the view blocked the post author.
            Console.WriteLine($"Post at {blockedPost.Uri} is blocked");
            break;
    }
}

These post types are included in the response so that a complete tree can be constructed. It's up to you to decide how to render these different states.

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