[Authoring] Templating doesn't support JSON keys with whitespace

[jvert]

Target Application

Teams, Copilot

Application Operating System

Windows

Schema Version

1.4

Problem Description

Given this card

{
    "type": "AdaptiveCard",
    "body": [
        {
            "type": "TextBlock",
            "text": "Product ${product}"
        },
        {
            "type": "TextBlock",
            "text": "Price ${unit price}"
        }
    ],
    "$schema": "http://adaptivecards.io/schemas/adaptive-card.json",
    "version": "1.6"
}

and this payload

{
    "product": "Widget",
    "unit price": "$42"
}

The card does not render at all in the designer. I could not find any documentation on the differences between property names as supported in the binding syntax vs. legal JSON key names. I tried a variety of escaping techniques with no success.

Expected Outcome

A way to bind to a JSON key that contains whitespace.

Actual Outcome

Card does not render in the designer
Value is rendered as "${unit price}" in Copilot

Card JSON

{
    "type": "AdaptiveCard",
    "body": [
        {
            "type": "TextBlock",
            "text": "Product ${product}"
        },
        {
            "type": "TextBlock",
            "text": "Price ${unit price}"
        }
    ],
    "$schema": "http://adaptivecards.io/schemas/adaptive-card.json",
    "version": "1.6"
}

Repro Steps

No response

[keshavk-msft]

Thank you for raising your issue. We will check this and will get back to you shortly.

[keshavk-msft]

Hi @jvert ,
Thank you for reporting this issue.

The behavior you're observing is due to a current limitation in the Adaptive Cards templating engine. Specifically, binding expressions do not support JSON keys that contain whitespace (e.g., "unit price"). As a result, expressions such as ${unit price} are not parsed correctly, which can lead to rendering failures or fallback behavior.

To resolve this, we recommend one of the following approaches:

Rename keys in your data model

1. Update your payload to use keys without spaces:
   { "type": "TextBlock", "text": "Price ${unit_price}" }

2. Preprocess your data before binding:
   If you do not control the data source, consider preprocessing the payload to convert keys with spaces into a more template-friendly format (e.g., replacing spaces with underscores) before rendering the card.

Thanks,
Keshav