slack-api-docs Attachments image_url doesn't show if alone

Image doesn't show when using postMessage if the attachment doesn't include the fallback or any additional text message. Unsure if this is intended or just not documented.

Doesn't work: https://api.slack.com/docs/formatting/builder?msg=%7B%22attachments%22%3A%5B%7B%22image_url%22%3A%22http%3A%2F%2Fplacehold.it%2F350x150.jpg%22%2C%22color%22%3A%22%23764FA5%22%7D%5D%7D

Works: https://api.slack.com/docs/formatting/builder?msg=%7B%22attachments%22%3A%5B%7B%22title%22%3A%22Network%20traffic%20(kb%2Fs)%22%2C%22image_url%22%3A%22http%3A%2F%2Fplacehold.it%2F350x150.jpg%22%2C%22color%22%3A%22%23764FA5%22%7D%5D%7D

May 02 '16 17:05 bbshih

+1

Feb 04 '17 01:02 patrickml

i'm wondering if there is just an issue with the preview system. I just tried to copy the Datadog example and the image isn't showing up either

https://api.slack.com/docs/messages/builder?msg=%7B%22attachments%22%3A%5B%7B%22fallback%22%3A%22Network%20traffic%20(kb%2Fs)%3A%20How%20does%20this%20look%3F%20%40slack-ops%20-%20Sent%20by%20Julie%20Dodd%20-%20https%3A%2F%2Fdatadog.com%2Fpath%2Fto%2Fevent%22%2C%22title%22%3A%22Network%20traffic%20(kb%2Fs)%22%2C%22title_link%22%3A%22https%3A%2F%2Fdatadog.com%2Fpath%2Fto%2Fevent%22%2C%22text%22%3A%22How%20does%20this%20look%3F%20%40slack-ops%20-%20Sent%20by%20Julie%20Dodd%22%2C%22image_url%22%3A%22https%3A%2F%2Fdatadoghq.com%2Fsnapshot%2Fpath%2Fto%2Fsnapshot.png%22%2C%22color%22%3A%22%23764FA5%22%7D%5D%7D

{
    "attachments": [
        {
            "fallback": "Network traffic (kb/s): How does this look? @slack-ops - Sent by Julie Dodd - https://datadog.com/path/to/event",
            "title": "Network traffic (kb/s)",
            "title_link": "https://datadog.com/path/to/event",
            "text": "How does this look? @slack-ops - Sent by Julie Dodd",
            "image_url": "https://datadoghq.com/snapshot/path/to/snapshot.png",
            "color": "#764FA5"
        }
    ]
}