Botframework-composer: support expression in body of http action

[xieofxie]

Is your feature request related to a problem? Please describe.

I'm always frustrated when I can't use expression in body

Describe the solution you'd like

Change to UI like options in begin dialog:

Describe alternatives you've considered

Additional context

[cwhitten]

@xieofxie please give more information in your request. It is possible to use both variables and expressions in the body of an HTTP call today.

[KayMKM]

Calendar skill need to add multiple attendee emails in http request body like:

"attendees": [
    {
      "emailAddress": {
        "address": "${user.ResolvedAttendees[0]}"
      }
    },
    {
      "emailAddress": {
        "address": "${user.ResolvedAttendees[1]}"
      }
    },
    ...
  ]

Now we can only add fixed count of items in list, because the body should be a json format.

[cwhitten]

why can't you use a foreach node with setproperty inside of it to create your object and then assign it into the body?

[KayMKM]

Do you mean that I create a attendee list object, then add it in body like this?

"attendees": [
    ${dialog.attendeeList}
  ]

This is not a valid json, so will get an error.

[cwhitten]

Ah, I see. I think you would want

{
  "attendees": ${dialog.attendeeList}
}

[KayMKM]

Yes. That is what I want.

[cwhitten]

We'll look to make this possible in R9

[xieofxie]

@cwhitten At first look I thought I can't use string(expression) in the body, however after some investigation, I found the following works:

• Assume dialog.a is an object/array/string
  This will serialize the content of a to data, thus object/array/string could be set dynamically

{
    "data":"=dialog.a"
}

• Assume dialog.a is an object
  This will serialize the content of a to json, thus key-value pairs could be set dynamically
  "=dialog.a"

@KayMKM will this solve your problem?

@hibrenda I may close this now. But this is different from #1829 as that one requires body could be other types instead of json

Thanks

[hibrenda]

@xieofxie thanks for the investigation. I just removed the link to issue 1829. And we also need to document or show this usage in sample as well @luhan2017 .