Facebook Marketing API Campaign spend_cap field returns inconsistently - facebook

Question

I'm trying to pull data for each of my Ad Campaigns from the Facebook Marketing API.
In the Ads Insights API there is only a 'spend' field that returns how much of the budget for that campaign has been spent so within the specified date range parameter. This is documented at
developers.facebook.com/docs/marketing-api/insights/fields/v2.9
I would like to get the 'spend_cap' field that's specified in the Reference section of the Marketing API located in the link below. One thing I noted was that there are no parameters available to this node, that may be why the spend_cap is not returning. This is documented at
developers.facebook.com/docs/marketing-api/reference/ad-campaign-group
I am using the following url to request the data.
https://graph.facebook.com/v2.9/{act_id}/campaigns?fields=name,spend_cap&access_token={access_token}
However, it returns the spend_cap field inconsistently, as shown below. I've only included a couple examples but I'm certain that all my campaigns are set up with spending caps.
data:[
{
"id": "##############",
"name": "name1",
"start_time": "2016-06-24T14:47:34-0400",
"stop_time": "2016-07-03T14:47:34-0400"
},
{
"id": "##############",
"name": "name2",
"spend_cap": "30000",
"start_time": "2016-05-16T11:57:10-0400"
},
{
"id": "##############",
"name": "name3",
"spend_cap": "15000",
"start_time": "2016-05-16T11:44:06-0400",
"stop_time": "2017-04-01T00:00:00-0400"
},
{
"id": "##############",
"name": "name4",
"start_time": "2016-05-13T15:34:41-0400",
"stop_time": "2017-05-13T09:46:44-0400"
}
]

Answer 1

The spend_cap at the campaign level is an optional field which is why it is only returned for some of the campaigns.
In general within the Graph API, if a field contains no data, this field will be omitted from the response.
Our SDKs abstract this for you so you can always access a field of an object, regardless of whether it was in the response, so if you're not using one of our SDKs, you'll have to do the same.