# Attachment object Slack's legacy secondary attachment: content in a box with a coloured bar down its side, sent in a message's `attachments` array next to (or instead of) `blocks`. ## Usage Attachments are not blocks. Send them in the message's top-level `attachments` array — on `chat.postMessage`, `chat.update`, `chat.postEphemeral`, `response_url` replies and the v1 chat message endpoints. The API hands them back as `attachments`, never inside `blocks`. Slack treats attachments as legacy; prefer blocks for new apps. They are still handy for a coloured status bar, or to wrap blocks in one: put Block Kit blocks in the attachment's `blocks` field and they render inside the box, controls included. A message can carry up to 20 attachments, shown after its blocks. When a message has attachments but no `blocks`, its top-level `text` is shown above them. Inside the box, Repzo shows the author line, the title, `text`, `fields`, `blocks`, `image_url` and then the footer; `pretext` sits above the box and `thumb_url` beside it. **A status update with fields** ```json { "text": "Weekly pipeline update", "attachments": [ { "color": "good", "fallback": "Northwind Trading renewal moved to Negotiation (SAR 48,000)", "pretext": "A deal moved forward in *Enterprise renewals*.", "author_name": "Pipeline bot", "title": "Northwind Trading renewal", "title_link": "https://example.com/deals/northwind-renewal", "text": "Stage changed from *Proposal* to *Negotiation*. Next step: send the revised quote by Thursday.", "fields": [ { "title": "Amount", "value": "SAR 48,000", "short": true }, { "title": "Close date", "value": "Nov 28, 2026", "short": true }, { "title": "Owner", "value": "<@3f6c2a1e-8b4d-4c7a-9e21-5d0b7f9a1c34|Account owner>", "short": true }, { "title": "Probability", "value": "70%", "short": true } ], "footer": "Repzo CRM", "ts": 1791813600 } ] } ``` **Blocks inside an attachment** ```json { "attachments": [ { "color": "#e01e5a", "fallback": "Invoice INV-2041 is 15 days overdue", "blocks": [ { "type": "section", "text": { "type": "mrkdwn", "text": "*Invoice INV-2041* for *Blue Harbor Logistics* is 15 days overdue.\nBalance due: *SAR 12,450*" } }, { "type": "actions", "elements": [ { "type": "button", "text": { "type": "plain_text", "text": "Send reminder" }, "style": "primary", "action_id": "send_reminder", "value": "INV-2041" }, { "type": "button", "text": { "type": "plain_text", "text": "Open invoice" }, "url": "https://example.com/invoices/INV-2041", "action_id": "open_invoice" } ] } ] } ] } ``` ## Fields | Field | Type | Description | Required? | |---|---|---|---| | `color` | String | Colour of the bar down the side of the box: `good` (green), `warning` (yellow), `danger` (red) or a hex colour code such as `#439FE0` (3 or 6 digits, `#` optional). | Optional | | `fallback` | String | A plain-text summary of the attachment. Used in notifications and message previews, and as the image's alternative text. Recommended. | Optional | | `pretext` | String | Text shown above the box. Formatted as `mrkdwn`. | Optional | | `author_name` | String | Small text naming the author, shown at the top of the box. | Optional | | `author_link` | String | An `http(s)` URL that `author_name` links to. Only works when `author_name` is set. | Optional | | `author_icon` | String | An `http(s)` URL of a small (16×16) image shown before `author_name`. Only works when `author_name` is set. | Optional | | `title` | String | Larger, bold text near the top of the box. | Optional | | `title_link` | String | An `http(s)` URL that `title` links to. | Optional | | `text` | String | The main body text of the attachment. Formatted as `mrkdwn`. | Optional | | `fields` | Object[] | A table of values shown under `text`. Each field is `{ "title": String, "value": String, "short": Boolean }`: `title` is a plain-text heading, `value` is `mrkdwn` (numbers are turned into strings), and `short: true` lets two fields sit side by side. | Optional | | `image_url` | String | An `http(s)` URL of an image shown full width inside the box. | Optional | | `thumb_url` | String | An `http(s)` URL of a small image shown on the right of the box. | Optional | | `footer` | String | Small text at the bottom of the box. | Optional | | `footer_icon` | String | An `http(s)` URL of a small (16×16) image shown before `footer`. | Optional | | `ts` | Number | A Unix timestamp (seconds; a numeric string also works). Shown in the footer as a date. | Optional | | `mrkdwn_in` | String[] | Which of `pretext`, `text` and `fields` to format as `mrkdwn`. | Optional | | `blocks` | Object[] | Block Kit blocks shown inside the box. They follow the same rules as top-level blocks and share the message's `block_id` space, so their controls send `block_actions` like any other. | Optional | > **How Repzo Chat differs from Slack** > > - `text` is formatted as `mrkdwn` unless `mrkdwn_in` is sent and leaves `text` out; then it shows exactly as written, line breaks kept. `pretext` and field values are always formatted as `mrkdwn`. > - Legacy attachment buttons (`actions`, `callback_id`) aren't supported and return a warning. Put an [actions block](https://workstation.repzo.com/docs/developers/block-kit/blocks/actions-block) in the attachment's `blocks` instead. > - `ts` is shown as the date only (`YYYY-MM-DD`), not as a relative time. > - A `color` that isn't `good`, `warning`, `danger` or a hex code returns a warning and the box has no coloured bar. An attachment with nothing to show also returns a warning. > - Other legacy fields (`author_subname`, `image_bytes`, `thumb_width`, `id`, …) are dropped. ## Examples ### A status update with fields Sent as `text` + `attachments`, without blocks: the text shows above the coloured box. ```json { "text": "Weekly pipeline update", "attachments": [ { "color": "good", "fallback": "Northwind Trading renewal moved to Negotiation (SAR 48,000)", "pretext": "A deal moved forward in *Enterprise renewals*.", "author_name": "Pipeline bot", "title": "Northwind Trading renewal", "title_link": "https://example.com/deals/northwind-renewal", "text": "Stage changed from *Proposal* to *Negotiation*. Next step: send the revised quote by Thursday.", "fields": [ { "title": "Amount", "value": "SAR 48,000", "short": true }, { "title": "Close date", "value": "Nov 28, 2026", "short": true }, { "title": "Owner", "value": "<@3f6c2a1e-8b4d-4c7a-9e21-5d0b7f9a1c34|Account owner>", "short": true }, { "title": "Probability", "value": "70%", "short": true } ], "footer": "Repzo CRM", "ts": 1791813600 } ] } ``` ### Blocks inside an attachment An attachment's `blocks` render inside the box, with working buttons. ```json { "attachments": [ { "color": "#e01e5a", "fallback": "Invoice INV-2041 is 15 days overdue", "blocks": [ { "type": "section", "text": { "type": "mrkdwn", "text": "*Invoice INV-2041* for *Blue Harbor Logistics* is 15 days overdue.\nBalance due: *SAR 12,450*" } }, { "type": "actions", "elements": [ { "type": "button", "text": { "type": "plain_text", "text": "Send reminder" }, "style": "primary", "action_id": "send_reminder", "value": "INV-2041" }, { "type": "button", "text": { "type": "plain_text", "text": "Open invoice" }, "url": "https://example.com/invoices/INV-2041", "action_id": "open_invoice" } ] } ] } ] } ``` ## Related - [Composition objects](https://workstation.repzo.com/docs/developers/block-kit/objects) - [Block Kit overview](https://workstation.repzo.com/docs/developers/block-kit)